Volume plasma and system and method for generating and using volume plasma

Abstract

A volume plasma may be generated between the first electrode and the second electrode. The first electrode and the second electrode may be separated from each other by a gap. The first electrode may include a first base layer and a plurality of first protruding portions extending in a first direction from the first base layer toward the second electrode. The first substrate layer may include a first conductive material. At least a portion of the first protruding portion may include a second conductive material. The melting temperature of the first conductive material and the melting temperature of the second conductive material may be at least 1000 K. During generation, a temperature of the volume plasma between the first electrode and the second electrode may be in a range of 1000-8000 K, including 1000 K and 8000 K.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 378,215, filed October 3, 2022, entitled “Tip-Enhanced Volumetric Plasma and Methods for Making and Using the Same”, and U.S. Provisional Application No. 63 / 513,567, filed July 13, 2023, entitled “A Uniform, Ultrahigh-Temperature Stable Plasma Operating at Atmospheric Pressure for the Synthesis of Extreme Materials”, the entire contents of which are incorporated herein by reference.

[0003] Statement on Federally Funded Research

[0004] This invention was completed with government funding under DESC0020233, a grant issued by the U.S. Department of Energy (DOE). The federal government owns certain rights to this invention. Technical Field

[0005] This disclosure generally relates to plasma systems and methods, and more specifically, to generating and using volumetric plasma, for example, by applying an electric field between electrodes. Background Technology

[0006] Plasma is formed when an electric field excites molecules electronically and vibrationally through electron collisions. While plasma has been used in materials processing, such as reactive ion etching and thin film deposition, conventionally generated plasmas remain challenging for fabricating large-scale bulk materials, particularly those with high melting points. For such fabrication, especially over large areas or volumes (e.g., >1 cm²), plasma generation presents significant challenges. 2 Achieving uniform high temperatures (e.g., >1000K) on a plasma surface is likely preferred. Volumetric plasmas (such as glow discharges) have been demonstrated. However, glow discharges typically require low pressures (e.g., <150 torr), in which case the plasma neutral gas temperature (T0) is limited. g Significantly lower than the electron temperature (T) e Due to the low temperature of neutral gases (e.g., <1000K), the ability of glow discharge to process high-temperature materials, especially in high-yield processing, is limited.

[0007] While arc discharge can be used to generate high-temperature plasmas (e.g., up to 10,000 K) at atmospheric pressure, the generated plasma exhibits a non-uniform temperature distribution in space and may be unstable. In particular, atmospheric arc discharges between conventional plate electrodes tend to contract into narrow, random arc channels (e.g., approximately 1 mm in diameter), resulting in extremely non-uniform temperature distribution. Needle electrodes help avoid random discharges. For example, high electrode curvature (e.g., a radius of several millimeters) can increase the local electric field strength and promote thermionic emission of secondary electrons. However, such a needle structure may confine the arc plasma to a narrow channel with a limited plasma volume. Using a rotating sliding arc can increase the discharge volume, but the plasma channel remains a narrow, filamentary structure, accompanied by non-uniform distribution of temperature and active material.

[0008] Embodiments of the disclosed subject matter can solve one or more of the problems and disadvantages described above, as well as other issues. Summary of the Invention

[0009] Embodiments of the disclosed subject matter provide systems and methods for generating volumetric plasmas, and uses of such volumetric plasmas, for example, to subject samples (e.g., precursors, reactants, or other materials) to high temperatures over a relatively large area, with enhanced temporal stability and / or spatial homogeneity. In some embodiments, volumetric plasmas can be generated by applying a voltage between pairs of electrodes separated by a gap. The surface of at least one electrode facing the gap may have a dense array of first protrusions extending toward the other electrode. The array of first protrusions can generate numerous concentrated electric fields that merge between the electrodes, thereby accelerating the transition from Townessen breakdown to arc discharge and expanding the initial spark discharge into volumetric plasma. In some embodiments, the surface of at least one electrode facing the gap may have one or more longer protrusions extending further toward the other electrode than the first protrusions, to contact or narrowly separate one or more portions of the other electrode. The longer protrusions can facilitate plasma initiation via spark discharge at lower breakdown voltages.

[0010] In one or more embodiments, the method may include generating a volumetric plasma between a first electrode and a second electrode spaced apart by a gap. The first electrode may include a first substrate layer and a plurality of first protrusions extending from the first substrate layer toward the second electrode along a first direction. The first substrate layer may include a first conductive material. At least a portion of the first protrusions may include a second conductive material. The melting temperature of the first conductive material and the melting temperature of the second conductive material may be at least 1000 K. During generation, the temperature of the volumetric plasma between the first and second electrodes may be in the range of 1000-8000 K, including 1000 K and 8000 K.

[0011] In one or more embodiments, the system may include a first electrode and a second electrode, a power supply, and a control system. The first electrode may include a first substrate layer and a plurality of first protrusions. The first substrate layer may include a first conductive material. At least a portion of the first protrusions may include a second conductive material. The melting temperature of the first conductive material and the melting temperature of the second conductive material may be at least 1000 K. The second electrode may be spaced apart from the first electrode by a gap. The plurality of first protrusions may extend from the first substrate layer toward the second electrode along a first direction. The power supply may be electrically coupled to the first and second electrodes. The control system may be operatively connected to the power supply and may be configured to control the operation of the power supply. The control system may include one or more processors and a computer-readable storage medium storing instructions that, when executed by the one or more processors, cause the power supply to apply a voltage between the first and second electrodes, thereby causing a volumetric plasma to be generated in or near the gap. The temperature of the volumetric plasma may be in the range of 1000-8000 K, including 1000 K and 8000 K.

[0012] Any of the various innovations disclosed herein can be used in combination or alone. This summary is provided to introduce, in a simplified form, some concepts that will be further described in the following detailed description. The summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. The foregoing, as well as other objects, features, and advantages of this disclosure, will become more apparent in the following detailed description, which will be illustrated in conjunction with the accompanying drawings. Attached Figure Description

[0013] The embodiments will now be described with reference to the accompanying drawings, which are not necessarily drawn to scale. Where applicable, some elements may be simplified or not shown to aid in the illustration and description of potential features. Throughout the drawings, the same reference numerals denote the same elements.

[0014] Figure 1AThis is a simplified schematic diagram of a system according to one or more embodiments of the disclosed subject matter, the system having electrodes having protrusions for generating volumetric plasma.

[0015] Figure 1B This is a simplified schematic diagram of another system according to one or more embodiments of the disclosed subject matter, the system having an electrode pair having protrusions for generating volumetric plasma.

[0016] Figure 2A It is a simplified perspective view of an electrode with protruding portions according to one or more embodiments of the disclosed subject matter.

[0017] Figure 2B This is a simplified perspective view of a fabric electrode with fibrous protrusions according to one or more embodiments of the disclosed subject matter.

[0018] Figure 2C A plan view of another fabric electrode having bundle-shaped fiber protrusions according to one or more embodiments of the disclosed subject matter is shown.

[0019] Figure 2D Images of a carbon felt electrode with bundled fiber protrusions, according to one or more embodiments of the disclosed subject matter, are shown.

[0020] Figure 2E A scanning electron microscope (SEM) image of the sharp tip of the fibrous protrusion of a carbon felt electrode according to one or more embodiments of the disclosed subject matter is shown.

[0021] Figures 2F-2G These are cross-sectional and plan views of an electrode with a two-dimensional pointed protrusion according to one or more embodiments of the disclosed subject matter.

[0022] Figures 2H-2I These are cross-sectional and plan views of an electrode according to one or more embodiments of the disclosed subject matter, the electrode having a protrusion with a blunt tip.

[0023] Figure 3A This is a simplified schematic diagram of a system according to one or more embodiments of the disclosed subject matter, the system having an electrode pair having a short protrusion and a long protrusion for generating volumetric plasma.

[0024] Figure 3B SEMS images of a carbon felt electrode having short fiber protrusions and long fiber protrusions according to one or more embodiments of the disclosed subject matter.

[0025] Figure 3CVarious aspects of using short fiber protrusions and long fiber protrusions to initiate and generate plasma according to one or more embodiments of the disclosed subject matter are shown.

[0026] Figure 3D It is a graph illustrating the current-voltage characteristics of using short fiber protrusions and long fiber protrusions to initiate and generate plasma according to one or more embodiments of the disclosed subject matter.

[0027] Figures 3E-3F This is a simplified schematic diagram of a system for generating volumetric plasma using electrodes having short and long protrusions, according to one or more embodiments of the disclosed subject matter.

[0028] Figure 3G This is a simplified schematic diagram of a system for initiating volumetric plasma using an external trigger, according to one or more embodiments of the disclosed subject matter.

[0029] Figure 3H Various aspects of initiating and maintaining volumetric plasma by varying the gap distance between the protrusions of an electrode pair, according to one or more embodiments of the disclosed subject matter, are illustrated.

[0030] Figure 4A Various aspects of using generated volumetric plasma to process particles are illustrated according to one or more embodiments of the disclosed subject matter.

[0031] Figure 4B Various aspects of using generated volumetric plasma to process one or more precursors according to one or more embodiments of the disclosed subject matter are illustrated.

[0032] Figure 4C Various aspects of using a generated volumetric plasma to process one or more precursor particles carried by a gas stream, according to one or more embodiments of the disclosed subject matter, are illustrated.

[0033] Figure 4D Various aspects of using generated volumetric plasma to process a stream of one or more reactants into one or more products, according to one or more embodiments of the disclosed subject matter, are illustrated.

[0034] Figures 4E-4F Various aspects of gravity-driven processing of one or more precursor particles using generated volumetric plasma are illustrated according to one or more embodiments of the disclosed subject matter.

[0035] Figure 4G Various aspects of using generated volumetric plasma to process one or more precursor particles into fine powder, according to one or more embodiments of the disclosed subject matter, are illustrated.

[0036] Figures 4H-4I These are perspective cross-sectional and plan views of a coaxial electrode configuration for generating volumetric plasma according to one or more embodiments of the disclosed subject matter.

[0037] Figures 4J-4K These are cross-sectional and plan views of another coaxial electrode configuration for generating focused volume plasma, according to one or more embodiments of the disclosed subject matter.

[0038] Figure 5A This is a simplified schematic diagram of a system for generating and scanning volumetric plasma according to one or more embodiments of the disclosed subject matter.

[0039] Figure 5B This is a simplified perspective view of a powder bed melting / sintering system employing volumetric plasma according to one or more embodiments of the disclosed subject matter.

[0040] Figure 5C This is a simplified schematic diagram illustrating various aspects of a plasma sintering / melting process using a focused volume plasma beam according to one or more embodiments of the disclosed subject matter.

[0041] Figures 5D-5E These are, respectively, plan views and side views of a support electrode configuration for generating volumetric plasma according to one or more embodiments of the disclosed subject matter.

[0042] Figure 5F This is a simplified cross-sectional view of a volumetric plasma system employing a support electrode configuration according to one or more embodiments of the disclosed subject matter.

[0043] Figure 6A This is a simplified process flow diagram of a method for generating and using volumetric plasma according to one or more embodiments of the disclosed subject matter.

[0044] Figure 6B A general example of a computing environment in which the disclosed techniques can be implemented is described.

[0045] Figure 7A It is a graph showing the measured temperature curve of the plasma generated using a carbon felt electrode.

[0046] Figure 7B This is an image of an experimental setup that uses carbon felt electrodes to generate volumetric plasma.

[0047] Figure 7C Images of carbon felt electrode pairs with short and long fibers are shown, along with a SEM image of the short fibers on one of the carbon felt electrodes.

[0048] Figure 7DThe image shows a SEM image of short fibers on a carbon felt electrode after plasma generation.

[0049] Figure 7E It is a graph showing the temperature of the central region of the generated plasma as a function of the input current when using a carbon felt electrode.

[0050] Figure 8A It is a graph of the voltage applied between carbon felt electrodes and the measured electric field generated by electric field-induced second harmonic generation (E-FISH).

[0051] Figure 8B This is a graph showing the voltage-current versus time curves for pulsed plasma operation of a carbon felt electrode pair.

[0052] Figure 9A The X-ray diffraction (XRD) pattern of Hf(C,N) synthesized using volumetric plasma generated by a carbon felt electrode pair is shown.

[0053] Figure 9B The XRD pattern of glassy MgO synthesized using volumetric plasma generated by a carbon felt electrode pair is shown.

[0054] Figure 9C Images show the conversion of carbon black into carbon nanotubes using volumetric plasma.

[0055] Figure 10A This is a cross-sectional SEM image of a tungsten sample synthesized using focused volume plasma in a powder bed melting / sintering process.

[0056] Figure 10B This is a cross-sectional SEM image of a high-entropy diboride (HEB) coating on a Nb-10Hf-1Ti alloy substrate, synthesized using volumetric plasma.

[0057] Figure 11 The XRD patterns of the mixed powder precursor and the atomized MoNbTaW alloy powder synthesized from the precursor using volumetric plasma are shown. Detailed Implementation

[0058] General principles

[0059] For ease of description, certain aspects, advantages, and novel features of embodiments of this disclosure are now described. The disclosed methods and systems should not be construed as limiting in any way. Rather, this disclosure is intended to cover all novel and non-obvious features and aspects, whether alone, in various combinations, or sub-combinations, of the various disclosed embodiments. These methods and systems are not limited to any particular aspect or feature or combination thereof, and the disclosed embodiments are not required to possess one or more particular advantages or to solve a particular problem. Techniques from any embodiment or example can be combined with techniques described in any one or more other embodiments or examples. Given that the principles of the disclosed techniques can be applied to many possible embodiments, it should be understood that the illustrated embodiments are merely exemplary and should not be considered as limiting the scope of the disclosed techniques.

[0060] Although some operations of the disclosed methods are described in a specific order for ease of expression, it should be understood that this descriptive style covers the rearrangement of the order of operations unless a specific order is required in specific language below. For example, operations described in sequence may be rearranged or performed simultaneously in certain situations. Furthermore, for simplicity, the accompanying drawings may not show various ways in which the disclosed methods can be used in conjunction with other methods. Additionally, the specification sometimes uses terms such as "provides" or "implements" to describe the disclosed methods. These terms are high-level abstractions of the actual operations performed. The actual operations corresponding to these terms may vary depending on the specific implementation and are readily recognizable by those skilled in the art.

[0061] Unless otherwise stated, the disclosure of numerical ranges should be understood to refer to each discrete point within the range, including the endpoints. Unless otherwise stated, all figures used in the specification or claims representing component quantities, molecular weights, percentages, temperatures, times, etc., should be understood to be modified by the term "about". Therefore, unless otherwise implied or explicitly stated, or unless the context is correctly understood by a person skilled in the art to have a more explicit interpretation, the numerical parameters described are approximate values ​​that may depend on the desired characteristics sought and / or the detection limits under standard test conditions / methods, as known to those skilled in the art. When directly and explicitly distinguishing this embodiment from the prior art discussed, the figures in the embodiments should not be considered approximate values ​​unless explicitly used with words such as "about," "substantially," or "approximately." Whenever "substantially," "approximately," "about," or similar language is explicitly used in conjunction with a particular value, it is intended to cover a range of up to 10% above or below that value, unless otherwise explicitly stated.

[0062] Orientation and other relative references are used to facilitate the discussion of the figures and principles herein, but are not intended to be limiting. For example, certain terms may be used, such as “inner,” “outer,” “upper,” “lower,” “top,” “bottom,” “internal,” “external,” “left,” “right,” “front,” “rear,” “rear side,” etc. These terms are used, where applicable, to provide some clarity when dealing with relative relationships, particularly with respect to the illustrated embodiments. However, these terms do not imply absolute relationships, positions, and / or orientations. For example, with an object, simply by flipping the object, the “upper” portion can become the “lower” portion. Nevertheless, it remains the same portion, and the object remains unchanged.

[0063] As used herein, unless the context clearly indicates otherwise, "comprising" means "including," and the singular forms "a," "an," or "the" all include the plural cases. Unless the context clearly indicates otherwise, the term "or" refers to a single element or a combination of two or more elements among the optional elements.

[0064] Although various alternatives exist for components, parameters, operating conditions, etc., this does not mean that these alternatives are necessarily equivalent and / or have the same performance. Unless otherwise stated, alternatives are not listed in a preferred order. Unless otherwise stated, any group defined below may be substituted or not substituted.

[0065] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. While methods and materials similar to or equivalent to those described herein may be used in practice or testing of this disclosure, suitable methods and materials are described below. Materials, methods, and examples are illustrative only and not limiting. The various features of the subject matter of this disclosure will become apparent in the following detailed description and appended claims.

[0066] Terminology Overview

[0067] The following content is provided to facilitate the description of various aspects of the disclosed subject matter and to guide those skilled in the art in practicing the disclosed subject matter.

[0068] Volumetric plasma: A three-dimensional volume of electrons, ions, and / or excited molecules generated and / or maintained by applying an electric field between electrodes. In some embodiments, plasma can be generated by applying a direct current (DC) voltage, an alternating current (AC) voltage (e.g., radio frequency (RF), such as RF in the range of 3 kHz to 300 GHz), or other waveforms (e.g., pulsed voltage waveforms) between the electrodes.

[0069] Fabric or felt: A structure formed of multiple fibers, for example by weaving the fibers together (forming a fabric) or otherwise coupling the fibers together (e.g., entanglement, compression, and / or extrusion to form a felt). In some embodiments, the fabric or felt may be formed from carbon fibers or metal fibers (e.g., refractory metals or refractory metal alloys). In some embodiments, carbon fabric or carbon felt may be obtained by carbonizing polyacrylonitrile (PAN) or rayon fibers (e.g., at a temperature of at least 1000 K).

[0070] Inert atmosphere: An atmosphere composed of one or more gases that do not undergo a chemical reaction at the temperature at which plasma is generated. In some embodiments, each gas in the inert atmosphere is selected from the following: nitrogen, argon, helium, neon, krypton, xenon, radon, and... gas.

[0071] Refractory materials: materials (e.g., elements or compounds) with a melting temperature (e.g., at atmospheric pressure) of at least 1000 K, such as a melting temperature of at least 1850 K (approximately 1580°C). In some embodiments, refractory materials may be as defined in ASTM C71-01 "Standard Terminology Relating to Refractories" (August 2017) (which is incorporated herein by reference). In some embodiments, refractory materials may be carbon (e.g., graphite, carbon fabric, carbon felt, carbon nanotubes), refractory metals, refractory metal alloys, refractory ceramics, or any combination thereof.

[0072] Refractory metal or refractory metal alloy: a metal or metal alloy with a melting temperature (e.g., at atmospheric pressure) of at least 1000 K, such as a melting temperature of at least 2100 K (about 1850°C). In some embodiments, the refractory metal may be niobium, molybdenum, tantalum, tungsten, rhenium, alloys thereof, or any combination thereof.

[0073] Refractory ceramics: Inorganic oxide, nitride, boride, or carbide materials with a melting temperature (e.g., at atmospheric pressure) of at least 1000 K. In some embodiments, the ceramic is electrically conductive, for example, having a conductivity of at least 10 Ω·cm at room temperature. -2 The electrical conductivity is measured in S / cm. In some embodiments, the ceramic can be a metal carbide, a metal nitride, a metal diboride, silicon carbide, or any combination thereof. In some embodiments, the metal carbide can be tantalum carbide, hafnium carbide, zirconium carbide, niobium carbide, titanium carbide, or any combination thereof. In some embodiments, the metal nitride can be tantalum nitride, hafnium nitride, zirconium nitride, niobium nitride, titanium nitride, or any combination thereof. In some embodiments, the metal diboride can be tantalum diboride, hafnium diboride, zirconium diboride, niobium diboride, titanium diboride, or any combination thereof.

[0074] High entropy refractory superalloys (RHEA): Alloys composed of five or more elements in substantially equal proportions, wherein at least some of the elements are refractory metals.

[0075] Powder: a plurality of particles, each of which has a maximum cross-sectional size (e.g., the diameter when the particle is spherical) less than or equal to about 1 mm. In some embodiments, the determined particle size represents the average particle size (e.g., the average of the maximum cross-sectional sizes) of all particles. In some embodiments, particle size may be measured according to one or more known standards, such as, but not limited to, ASTM B214-16 entitled "Standard Test Method for Sieve Analysis of Metal Powders", ASTM B330-20 entitled "Standard Test Methods for Estimating Average Particle Size of Metal Powders and Related Compounds Using Air Permeability", ASTM MB822-20 entitled "Standard Test Method for Particle Size Distribution of Metal Powders and Related Compounds by Light Scattering", and ASTM B922-20 entitled "Standard Test Method for Metal Powder Specific Surface Area by Physical Adsorption", all of which are incorporated herein by reference.

[0076] Nanoparticles: engineered microparticles formed of one or more elements, having a maximum cross-sectional size (e.g., the diameter when the microparticle is spherical) less than or equal to about 1 μm, such as about 500 nm or less. In some embodiments, the maximum cross-sectional size of the nanomaterial is less than or equal to about 300 nm, such as in the range of 10-100 nm, including 10 nm and 100 nm. In some embodiments, the nanomaterial is formed of at least two (2) elements, such as three (3) or more elements.

[0077] Overview

[0078] This document discloses systems and methods for generating volumetric plasmas and their applications (e.g., for material synthesis, material manufacturing, and / or material catalysis). In some embodiments, the generated volumetric plasma can be generated over a relatively large area (e.g., ≥1 cm²). 2 The volumetric plasma exhibits high temperatures (e.g., >1000K, e.g., 3000-8000K). In some embodiments, the generated volumetric plasma may exhibit enhanced temporal stability, enhanced spatial homogeneity, or both. For example, the volumetric plasma may be substantially stable over time, with the peak temperature at a point within its volume, the average temperature over its volume, and / or the temperature at a point within its volume varying by no more than 10% over at least 1 minute (e.g., ≥10 minutes). Alternatively or additionally, the volumetric plasma may have a substantially uniform temperature over its volume (or at least over a lateral region in a plane perpendicular to the gap thickness), e.g., the temperature at each point in the plasma deviates by no more than 10% from the peak temperature or the average plasma temperature.

[0079] Volumetric plasma can be generated by applying a voltage between electrode pairs separated by a gap, and the surface of at least one electrode facing the gap can have multiple protrusions (e.g., pillars, fibers, tips, or other surface protrusions). The use of protrusions can help reduce the voltage required for gas breakdown and / or allow for the attainment of a homogeneous volumetric plasma at lower currents and power. In particular, unlike conventional arc discharge, protrusions can generate enhanced electric fields that merge between the electrode surfaces, thereby accelerating the transition from Townsend breakdown to arc, increasing the size and volume of the plasma, and enhancing plasma homogeneity. Furthermore, this expansion can generate collective thermal effects, which contribute to plasma stabilization.

[0080] For example, Figure 1AA plasma generation system 100 is shown, comprising a first electrode 102, a second electrode 104, a power supply 108, and a controller 110. In the illustrated example, the first electrode 102 and the second electrode 104 are separated by a gap 106 of thickness g, and the first electrode 102 has a plurality of first protrusions 116 (labeled 114) extending toward the second electrode 104 (e.g., along the y-direction). In some embodiments, the thickness g of the gap 106 may be less than 10 cm, for example, in the range of 1 mm to 1 cm. A voltage (DC, AC, or other waveforms, such as pulsed voltage waveforms) can be applied between the electrodes 102 and 104 by the power supply 108 to form a volumetric plasma 118 within the gap 106. In some embodiments, during the volumetric plasma 118, the peak voltage applied between the electrodes 102 and 104 may be less than or equal to 100 V (e.g., ≤50 V), and / or the peak current between the electrodes 102 and 104 may be less than or equal to 100 A (e.g., ≤50 V).

[0081] In some embodiments, volumetric plasma 118 can be generated at any pressure (e.g., in the range of 1 Torr to 10 atm) with or without a magnetic field applied. For example, volumetric plasma 118 can be generated at atmospheric pressure (e.g., approximately 1 atm). In some embodiments, volumetric plasma 118 can exhibit a substantially uniform temperature over the lateral extent 120 of the plasma (e.g., in the xz plane). In some embodiments, the lateral extent 120 of volumetric plasma 118 can be at least 1 mm, for example, in the range of 1 mm to 100 cm. In some embodiments, the temperature at different points along the lateral extent 120 of volumetric plasma 118 can be at plasma temperature T. P Within a narrow band 122 nearby, for example, the temperature is less than or equal to 10% of the plasma temperature (e.g., if T...). P =1000K, then =±50K). In some embodiments, the plasma temperature T P The temperature can be at least 1000 K, for example, in the range of 3000-8000 K. Alternatively, in some embodiments, the volumetric plasma 118 can be a non-thermal plasma or a cold plasma, for example, in which the temperature of electrons is greater than 1000 K (e.g., in the range of 3000-8000 K), while the temperature of heavy particle swarms (e.g., ions and neutral particles) is less than 1000 K (e.g., equal to or close to room temperature). In some embodiments, the plasma temperature T P It can be the average temperature over the entire volume of plasma across the transverse range 120, or the temperature at the center of the transverse range 120 of the plasma (e.g., in the xz plane).

[0082] In some embodiments, the plasma temperature T can be changed by selecting or altering the power input from the power source 108 (e.g., higher power corresponds to higher temperature), selecting or altering the distance g of the gap 106 (e.g., a smaller gap corresponds to higher temperature), and / or selecting or altering the gas pressure between the two electrodes 102, 104 (e.g., higher pressure corresponds to higher temperature). P In some embodiments, the volumetric plasma can be time-stable, for example, the temperature distribution over the lateral range 120° and / or the plasma temperature T. P Under substantially constant power input (e.g., the power of a DC signal, the power and frequency of an AC signal, the power and frequency of a pulse voltage waveform, etc.), remain nearly consistent for a period of time, for example, remain nearly consistent for at least 1 minute (e.g., remain nearly consistent for ≥10 minutes).

[0083] Controller 110 can control the operation of power supply 108, such as controlling the timing, manner, and / or magnitude of voltage, current, or electrical power applied to electrodes 102, 104, which in turn can control the characteristics of the volumetric plasma (e.g., on / off, temperature, etc.). In the illustrated example, controller 110 is operatively coupled to power supply 108. Alternatively or additionally, controller 110 and power supply 108 can be considered as part of a single system, such as different modules of system 124. In some embodiments, controller 110 can control other aspects of system 100, such as the size of gap 106 and / or the pressure between electrodes 102, 104.

[0084] exist Figure 1A In the example shown, the protrusion extends from the base layer 112 of the first electrode 102. In some embodiments, the protrusion may be disposed on or formed from the surface of the base layer 112, for example... Figure 1A The upper illustration shows multiple pillars 116a (labeled 114a). Alternatively or additionally, in some embodiments, the protrusions are exposed or cut-off surface portions of the base layer 112, for example... Figure 1A The lower illustration shows a plurality of fibers 116b (labeled 114b). In some embodiments, each protrusion 116 may have a cross-sectional dimension (e.g., the maximum or minimum cross-sectional dimension in the xz plane, such as diameter) d less than or equal to 500 μm. In some embodiments, the cross-sectional dimension d of the protrusion 116 may be greater than 1 μm, for example, in the range of 1-100 μm. In some embodiments, the cross-sectional dimension d may represent the average value of each protrusion 116, wherein the cross-sectional dimension of the protrusion 116 is within ±10% of the average value.

[0085] In some embodiments, the spacing s between adjacent protrusions 116 (e.g., along the x-direction, along the z-direction, and / or along the xz plane) may be less than or equal to 1 mm. In some embodiments, the spacing s may be approximately equal to or less than the cross-sectional dimension d, for example, less than or equal to 100 μm (e.g., in the range of 1-50 μm). In some embodiments, the spacing s may represent the average spacing across a plurality of 114. In some embodiments, the individual spacing between pairs of protrusions 116 may be within 10% of the average value. In some embodiments, the combination of the cross-sectional dimension d and the spacing s may generate a center-to-center spacing c less than 1 mm (e.g., 1-100 μm). Alternatively or additionally, the plurality of 114 may exhibit at least 10 4 One prominent part / cm 2 The density, for example, is about 10. 5 Parts / cm 2 .

[0086] Alternatively or additionally, the spacing s may be less than or approximately equal to (e.g., within one order of magnitude) the Debye length of system 100. Debye length ( The Debye length describes the distance over which a charge is gradually shielded and its potential exponentially decreases to 1 / e of its initial value, where e is the electron charge. The Debye length can be calculated using the following formula:

[0087] in, It is Planck's constant (1.38e -23 J / K=8.617e -5 eV / K), It is the electron temperature (e.g., approximately 4000-8000K). It is the electron density (e.g., approximately 10). -12 cm -3 ),and It is the plasma dielectric constant (e.g., 55.26e). 2 / (eV•μm)). In some embodiments, as the spacing approaches the Debye length, the electric fields generated by the protrusions can merge in the early stages of plasma formation, which helps to form a uniform volumetric plasma. For example, assuming as well as = 10 12 cm -3 Debye length It can be estimated to be about 6.2 μm, and the spacing s can be in the range of 1-10 μm.

[0088] In some embodiments, the length h of the protrusion 116 (e.g., along the y-direction from the surface of the base layer 112) may be greater than its cross-sectional dimension d. Alternatively or additionally, the length h of the protrusion 116 may be less than the gap dimension g. In some embodiments, the length h of the protrusion 116 may be greater than or equal to 100 μm and / or less than or equal to 1 μm, for example, in the range of 200-500 μm. In some embodiments, the length h may represent the average length of a plurality of 114. In some embodiments, the length of each protrusion 116 may be within 10% of the average value. In some embodiments, each protrusion may be substantially straight and extend substantially parallel to the thickness of the gap (e.g., parallel to the y-direction), for example as... Figure 1A As shown in column 116a. Alternatively or additionally, in some embodiments, each protrusion may deviate from a generally straight shape in at least a portion of its length, and / or have a portion angled relative to the gap thickness (e.g., extending in the xz plane), such as... Figure 1B As shown in fiber 116b, in this case, the length h can be the distance the protrusion extends along the y direction.

[0089] In some embodiments, the first electrode 102 and the second electrode 104 may be formed of a conductive material capable of withstanding plasma temperatures, for example, a conductive material having a melting temperature of at least 1000 K (e.g., at atmospheric pressure). For example, the first electrode 102 and / or the second electrode 104 may be formed of a refractory material (e.g., carbon, refractory metals or alloys, and / or refractory ceramics). In some embodiments, the base layer 112 of the first electrode 102 may be formed of a conductive material different from that of the plurality of protrusions 114. For example, the base layer may be graphite, and the protrusions may be refractory metals (e.g., when pillars 116a are formed on the base layer 112). Alternatively, in some embodiments, the base layer 112 and the protrusions may be formed of the same conductive material (e.g., when the plurality of 114 and the base layer 112 are both composed of fibers 116b).

[0090] exist Figure 1A In the example shown, the second electrode 104 is configured as a planar electrode without any protrusions. In some embodiments, the first electrode 102 with protrusions can function as an anode, while the second electrode 104 without protrusions can function as a cathode. However, in some embodiments, the second electrode 104 may also have its own protrusions. For example, Figure 1B A plasma generation system 130 is shown, which includes a first electrode 102, a second electrode 134, a power supply 108, and a controller 110. Similar to... Figure 1AFor example, the first electrode 102 has a plurality of protrusions 114 on the substrate layer 112, which are spaced apart from the second electrode 134 by a gap 136 of thickness g. However, the second electrode 134 has another plurality of protrusions 144 on the substrate layer 142, which may have the same or different configuration (e.g., shape, size, spacing and / or material) as the plurality of 114 of the first electrode 102.

[0091] In some embodiments, the volumetric plasma 118 can be used for material synthesis or processing (e.g., bulk materials, powders, nanoparticles, nanotubes, nanomaterials), chemical reactions (e.g., converting one or more reactants into one or more products with or without a catalyst), sterilization (e.g., treating food or medical devices using cold plasma), or for any other purpose for which applying plasma temperature may be useful. In some embodiments, the plasma generation system can provide rapid cooling (e.g., ≥10°C) after high-temperature application. 2 K / s, for example in 10 3 Up to 10 5 (within the range of K / s), for example by removing the treated material from the volumetric plasma, reducing the temperature of the volumetric plasma, shutting off the volumetric plasma, and / or providing active cooling methods (e.g., jetting airflow towards the treated material, using a heat exchanger, etc.).

[0092] Example of electrode configuration

[0093] In some embodiments, one or both electrodes in the plasma generation system may comprise an array of protruding portions. For example Figure 2A The arrangement of electrode 200 is shown, which has a two-dimensional array (e.g., in the xz plane) of protrusions 204 formed on a substantially flat substrate layer 202. Figure 2A In the example shown, the protrusion 204 is shaped as a cylinder or rod; however, other shapes are possible depending on one or more of the intended embodiments. In some embodiments, the base layer 202 and at least some of the protrusions 204 may be made of a refractory material, such as a refractory metal.

[0094] In some embodiments, the protrusions 204 can be formed by three-dimensional printing, such as, but not limited to, laser-based direct energy deposition or laser powder bed melting. Alternatively or additionally, in some embodiments, the array of protrusions can be formed from a base layer, such as by cutting, grinding, and / or roughening the surface of a fabric or felt formed from refractory fibers (e.g., carbon fibers or metal fibers). Figure 2B The configuration of an electrode 210 with a protrusion 212 is shown, the protrusion 212 being formed of fibers broken at the cut surface of the carbon fabric and / or fibers exposed from the cut surface.

[0095] In some embodiments, the base layer may comprise woven fibers, and the protruding portions may be arranged in bundles based on a woven pattern. For example Figures 2C-2D The configuration of electrode 220 is shown, which has bundles 222a-222c of cut fibers 224 held together but separated by laterally oriented fibers 226. Within each bundle 222a-222c, the cut fibers 224 can be separated from each other (e.g., along the xz plane) by an intra-bundle spacing s1, for example, this intra-bundle spacing s1 is similar to that described above regarding... Figure 1A The spacing s described. Between bundles (e.g., in Figure 2C Between bundles 222a and 222b, adjacent cut fibers 224 can be separated by an inter-bundle spacing s greater than the intra-bundle spacing s1. b Separate, the spacing s between the bundles b For example, less than or equal to 500µm (e.g., in the range of 50-250µm). In some embodiments, the transverse fiber 226 may be used as a base layer or support layer, and the cut fiber 224 extending (e.g., along the y-direction) beyond the transverse fiber 226 may be used as a protruding portion.

[0096] In some embodiments, the exposed end of the protruding portion (e.g., adjacent to the gap) may have a narrowing or tapering shape, such as a one-dimensional tip. For example, Figure 2E An electrode 230 with a bundle 232 of cut fibers 234 is shown, the cut fibers 234 having been sharpened to have tapered tips 236, which can further reduce the barrier to arc discharge. In some embodiments, the sharpening of the fiber tips can be a result of initial plasma generation. For example, after the first plasma breakdown, the tips of the carbon fibers can be gradually sharpened to have a tapered shape due to temperature and local electric field. Other forms of tip sharpening are also possible according to one or more contemplated embodiments. Alternatively or additionally, in some embodiments, the protrusions may have tips that narrow or taper in only one dimension, such as forming two-dimensional tips. For example, Figures 2F-2G An electrode 240 configuration with elongated protrusions 244 formed on a substrate 242 is shown, and each protrusion may have a corresponding two-dimensional tip 246 (e.g., a blade edge).

[0097] Alternatively or additionally, in some embodiments, the protruding portion may be formed as a protruding surface feature of the underlying block component, such as a rounded or blunt tip. For example, Figures 2H-2I The configuration of electrode 250 is shown, which has multiple protrusions formed by surface features 252a of a base layer 252b. Figures 2H-2IIn the example shown, the protrusion is a circular protrusion 254 surrounded by a recessed surface portion 256. The protrusion 254 may have a maximum cross-sectional dimension w (e.g., along the xz plane), which is similar to, for example, the one referenced above. Figure 1A The described cross-sectional dimension d, and / or the protrusion 254, can be represented by a center-to-center spacing c (e.g., similar to the reference above). Figure 1A The spacing s described is separated from the adjacent protrusion.

[0098] although Figures 2A-2I The protruding portions are shown to have the same size and shape, but in some embodiments, one, some, or all of the protruding portions may have a different size and / or shape than the other protruding portions. Furthermore, Figures 2A-2I A regular array of protrusions is shown, but embodiments of the disclosed subject matter are not limited thereto. Rather, in some embodiments, the spacing, size, and / or shape of the protrusions may vary on the surface of the electrode (e.g., along the x-direction, along the z-direction, or both). For example, the array of protrusions may have variable spacing or a random arrangement.

[0099] Examples of structures and configurations for volumetric plasma initiation

[0100] In some embodiments, a system for generating volumetric plasma may include means for initiating the plasma, such as by setting a distance smaller than the gap between the electrodes, causing a gas discharge to occur at a voltage lower than other possible voltages. In some embodiments, the initiation means may be temporary, for example, removed or changed once the plasma is initiated. In some embodiments, the initiation means may be reusable or recyclable, for example, the initiation means may initiate the plasma between the electrodes multiple times. Alternatively, in some embodiments, the initiation means may be consumable, for example, the initiation means may degrade or decompose due to the high temperature of the generated volumetric plasma.

[0101] In some embodiments, volumetric plasma can be generated by applying a voltage between electrodes separated by a first gap. The surface of at least one electrode facing the first gap may have a plurality of first protrusions, and the surface of at least one electrode facing the first gap may have a plurality of second protrusions (e.g., pillars, fibers, tips, or other surface protrusions). In some embodiments, the first and second protrusions may be located on the same surface, with the second protrusions being longer than the first protrusions to extend into the first gap between the electrodes. In some embodiments, the second protrusions form a narrower second gap with another electrode (e.g., the surface of another electrode facing the gap, a first protrusion extending from the surface of the other electrode, or a second protrusion extending from the surface of the other electrode). In some embodiments, the narrower second gap may be at least an order of magnitude smaller than the first gap and / or have a size within an order of magnitude of the cross-sectional size of the second protrusion. In some embodiments, gas discharge can occur on the second gap at a voltage (or power) much lower than that required to generate gas discharge on the first gap, for example, at least an order of magnitude lower.

[0102] For example, Figure 3A A plasma generation system 300 is shown, comprising a first electrode 302, a second electrode 304, a power supply 108, and a controller 110. In the example shown, the first electrode 302 is spaced from the second electrode 304 by a first gap 306 (e.g., having a thickness g). In some embodiments, the gap 306 may be less than 10 cm, for example, in the range of 1 mm to 1 cm. The first electrode 302 may have a plurality of first protrusions 114 extending toward (e.g., along the y-direction) the second electrode 304, and the second electrode 304 may have its own plurality of second protrusions 144 extending toward (e.g., along the y-direction) the first electrode 302. Furthermore, the first electrode 302 may have one or more second protrusions 308 extending further (e.g., along the y-direction) than the plurality of first protrusions 114, and the second electrode 302 may have one or more second protrusions 310 extending further (e.g., along the y-direction) than the plurality of first protrusions 144. The second protrusion 310 of the second electrode may have the same or different configuration (e.g., shape, size, spacing and / or material) as the second protrusion 308 of the first electrode 302.

[0103] In some embodiments, the second protrusions 308, 310 may be disposed on or formed by the surfaces of the respective base layers 112, 142. For example, the second protrusions are similar to but longer than […]. Figure 1AThe upper illustration shows column 116a. Alternatively or additionally, in some embodiments, the second protrusions 308, 310 are exposed or cut surface portions of the respective base layers 112, 142, for example, similar to but longer than Figure 1A The fiber 116b is shown in the lower illustration. In some embodiments, each second protrusion 308, 310 may have a cross-sectional size (e.g., the largest or smallest cross-sectional size in the xz plane, such as the diameter) that is approximately the same as the cross-sectional size of the corresponding plurality of first protrusions 114, 144, for example less than or equal to 500 μm. In some embodiments, the cross-sectional size of the second protrusions 308, 310 may be greater than 1 μm, for example in the range of 1-100 μm. In some embodiments, the cross-sectional size may represent the average value of each second protrusion 308 or each second protrusion 310, and the cross-sectional size of the second protrusions 308, 310 is within 10% of the corresponding average value.

[0104] In some embodiments, the second protrusions 308, 310 extend into and across the gap 306 to initially contact each other and form a high-resistance contact point and / or form a narrow gap region 312 (e.g., on the order of the respective cross-sectional dimensions, e.g., ≤5 μm), which can facilitate the initiation of volumetric plasma at lower voltages. In some embodiments, each second protrusion 308, 310 may extend a distance L from the respective substrate layer 112, 142 along the thickness direction of the gap 306 (e.g., along the y-direction). In some embodiments, the distance L may be greater than or equal to 1 mm, for example, in the range of 10-100 mm. In some embodiments, the distance L may represent an average value across the respective electrodes 302, 304, and the distance by which each second protrusion 308, 310 extends along the gap thickness direction may be within 10% of the average value. In some embodiments, each second protrusion 308, 310 may deviate from a straight line shape for at least a portion of its length, and / or have a portion angled relative to the gap thickness (e.g., extending in the xz plane), for example as Figures 3A-3B As shown, in this case, distance L represents the distance the second protrusion extends along the y-direction. Alternatively or additionally, in some embodiments, each second protrusion may be substantially straight and extend substantially parallel to the thickness of gap 306 (e.g., parallel to the y-direction), such that distance L represents the length of the corresponding second protrusion.

[0105] In some embodiments, the first electrode 302 and the second electrode 304 may be formed of a conductive material capable of withstanding plasma temperatures, for example, the conductive material having a melting temperature of at least 1000 K (e.g., at atmospheric pressure). For example, the first electrode 302 and / or the second electrode 304 may be formed of a refractory material (e.g., carbon, refractory metals or alloys, and / or refractory ceramics). In some embodiments, the base layer 112 of the first electrode 302 may be formed of a conductive material different from the plurality of first protrusions 114 and / or a conductive material different from the second protrusion 308. Similarly, the base layer 142 of the second electrode 304 may be formed of a conductive material different from the plurality of first protrusions 144 and / or a conductive material different from the second protrusion 310. Alternatively, in some embodiments, such as Figure 3B As shown, for example, when multiple first protrusions 114 (e.g., short fibers), second protrusions 308 (e.g., long fibers) and base layer 112 are all formed of fibers, base layer 112, multiple first protrusions 114 and / or second protrusions 308 can be formed of the same conductive material.

[0106] In some embodiments, the contacting or narrowed gap region 312 of the second protrusions 308, 310 can facilitate the initiation of volumetric plasma at a voltage lower than the possible voltage across the gap 306. Once initiated, the volumetric plasma can develop and be maintained on and over the plurality of first protrusions 114 of the first electrode 302 and the plurality of first protrusions 144 of the second electrode 304. For example Figures 3C-3D The various aspects of plasma initiation and generation in system 300 are illustrated. In the initial stage 320, a voltage can be applied to the gap 306 via electrodes 302, 304, causing current to flow through the contacting second protrusion and inducing Joule heating of the contacting second protrusion. Due to the current flow, the second protrusion may begin to glow, although no plasma is formed. Joule heating is intensified at the defect region or contact point of the second protrusion where the resistance is highest, thereby generating localized ultra-high temperatures (e.g., generating temperatures greater than the melting temperature of the second protrusion, such as greater than 4000 K), which causes the corresponding portion of the second protrusion to fracture.

[0107] This self-terminating process creates a very narrow gap 314 between the second protrusions, approximately the diameter of the second protrusions (about 10 μm). Due to the formation of this gap, current can no longer flow through the second protrusions, and even with the increased voltage in the second stage 322, the gap between the first and second electrodes remains dark. A further increase in voltage in the third stage 324 initiates a gas discharge. Specifically, the locally enhanced electric field at the tip of the second protrusion promotes the emission of a second electron, resulting in a spark discharge between the newly formed gaps 314. This spark discharge, in turn, contributes to the low breakdown voltage (e.g., V0).I The plasma is initiated at ≤ 100V (e.g., approximately 40-45V). Once initiated, the plasma can grow during the fourth stage 326, in which densely packed, shorter first protrusions generate a tip-enhanced electric field that coalesces between the electrode surfaces, accelerating the transition from Townsend breakdown to arcing, expanding the size and volume of the plasma, and increasing its homogeneity, unlike conventional arc discharge. This expansion also generates a collective thermal effect, contributing to plasma stabilization. As the plasma expands, the voltage begins to decrease from the breakdown voltage (accompanied by an increase in current) until the plasma reaches its stable volume form, corresponding to the applied voltage V. P By continuing to apply sufficient power (e.g., 400-800 W) between electrodes 302 and 304, the volumetric plasma can be sustained and stabilized for at least one minute (e.g., at least 10 minutes), or in some embodiments, it can remain stable indefinitely, depending on the plasma temperature and the materials used in the system.

[0108] exist Figure 3A In the example shown, the second electrode 304 is configured as a base layer 142 having a first protrusion and a second protrusion. However, in some embodiments, the second electrode may only have a second protrusion. For example... Figure 3E A portion of a plasma generation system 340 is shown, the system having a first electrode 302 and a second electrode 344 spaced apart from the first electrode 302 by a gap 346. Similar to... Figure 3A For example, the first electrode 302 has a plurality of first protrusions 114 and a plurality of second protrusions 308. However, the second electrode 344 has only a second protrusion 342, which may have the same or different configuration (e.g., shape, size, spacing, and / or material) as the second protrusions 308 of the first electrode 302. The operation of system 340 may be the same as system 300 in other respects, for example, as referenced above. Figures 3C-3D As stated above.

[0109] Alternatively, in some embodiments, the second electrode may not have any protrusions. For example... Figure 3F A portion of a plasma generation system 350 is shown, the system having a first electrode 302 and a second electrode 352 spaced apart from the first electrode 302 by a gap 356. Similar to... Figure 3AFor example, the first electrode 302 has a plurality of first protrusions 114 and a plurality of second protrusions 354. However, the second electrode 352 has no protrusions. Instead, at least a portion of the second protrusions 308 is long enough to extend through the gap 356, thereby initially contacting the second electrode 352 and forming a high-resistance contact point and / or forming a narrow gap region 358. The operation of system 350 may otherwise be the same as system 300, for example, as referenced above. Figures 3C-3D As stated above. Figure 3F In the example shown, the second electrode 352 is a bare electrode without any first protrusion; however, according to one or more contemplated embodiments, the second electrode may also have a first protrusion (e.g., similar to...). Figure 1B (the configuration of electrode 134 in the middle), and the second protrusion 308 can contact the first protrusion of the second electrode or form a narrow gap region 358.

[0110] Alternatively, in some embodiments, neither the first nor the second electrode has a second protrusion. Instead, a separate trigger (e.g., a wire) can be used to initiate the plasma at a lower voltage than using the electrodes alone. In some embodiments, after plasma initiation, this separate component can be consumed by the plasma (e.g., having a melting temperature below that of the plasma) or removed from the plasma. For example, Figure 3G A plasma generation system 360 is shown, comprising a first electrode 102, a second electrode 134, a power supply 108, a controller 110, and a trigger member 362 (e.g., a wire). The trigger member 362 may be disposed within the gap between the electrodes 102 and 134, such that a narrow gap 364 (e.g., ≤10 μm) is formed between an end of the trigger member 362 and an end of one of the first protrusions of the first electrode 102. In operation, gas discharge through the narrow gap 364 can facilitate plasma initiation at a lower voltage, after which the plasma can expand throughout the first electrode 102 and the second electrode 134 and fill the gap between the first electrode 102 and the second electrode 134.

[0111] exist Figure 3G In the illustrated example, the trigger member 362 is arranged to form a narrower gap relative to a portion of the first electrode 102. Alternatively, in some embodiments, the trigger member 362 may be configured such that a narrower gap is formed between the end of the trigger member and the end of one of the first protrusions of the second electrode 134. In the illustrated example, the trigger member 362 forms a narrower gap 364 with one of the first protrusions. Alternatively, in some embodiments, the narrower gap 364 may be formed relative to a plurality of first protrusions and / or relative to different portions of any electrode, for example when a longer second protrusion is provided.

[0112] In some embodiments, instead of or in addition to providing a second protrusion and / or a separate trigger, the thickness of the gap can be varied to facilitate plasma initiation. For example, Figure 3H A portion of a plasma generation system 370 is shown, employing a variable gap between a first electrode and a second electrode. In the illustrated example, the first electrode has a base layer 112 with a plurality of first protrusions 114, and the second electrode has a base layer 142 with a plurality of first protrusions 144. However, other configurations of the first and / or second electrodes are possible according to one or more contemplated embodiments. In the illustrated example, the first electrode is mounted on or supported by a first translation stage 372a having a motor 374a, and the second electrode is mounted on or supported by a second translation stage 372b having a motor 374b. The first and second translation stages 372a, 372b can be configured to move the first and second electrodes toward or away from each other to change the size of the gap between the first and second electrodes. According to one or more of the intended embodiments, other configurations of the first and second translation stages are also possible, such as setting up a translation stage for one electrode while the other electrode is held in a fixed position, mounting both electrodes on a common translation stage, using a translation stage without a motor, or any other means for changing the gap size between the electrodes.

[0113] To initiate plasma, a first electrode (e.g., having a base layer 112 and a plurality of first protrusions 114) and a second electrode (e.g., having a base layer 142 and a plurality of first protrusions 144) can be positioned to form a gap g1 of a first thickness, as shown in 380. Applying a voltage across g1 can generate a gas discharge 376 between the first protrusions of the portion, which can extend via the remaining portions of the plurality of first protrusions 114, 144, thereby generating a volumetric plasma 378. Once plasma 378 has been generated, the first and second electrodes can be moved apart to form a gap g2 of a second thickness, which is larger than gap g1. As the electrodes are moved apart, the power applied to the electrodes can be controlled to maintain the plasma (e.g., by increasing the current and / or voltage). As shown in 382, ​​once the desired gap spacing is achieved, the volumetric plasma 378 can be used for a specific application. In some embodiments, a voltage can be applied between the electrodes while they are being moved prior to plasma initiation. For example, a voltage can be applied such that the gap between the electrodes gradually decreases until plasma initiation. Once started, the gap between the electrodes can be maintained or gradually increased until the desired gap thickness is achieved.

[0114] Example configuration using volumetric plasma

[0115] As mentioned above, the generated volumetric plasma can be used for materials synthesis, processing, or chemical reactions. In addition to subjecting materials to controlled high temperatures (e.g., in the range of 1000-8000 K), changes in the electromagnetic field within the volumetric plasma can produce synergistic effects during manufacturing or catalysis.

[0116] For example Figure 4A A plasma system configuration 400 is shown for sintering or otherwise heating precursor particles 402 (e.g., having a diameter of at least 10 mm, such as 15-30 mm) to form a bulk product. Instead of particles, or in addition to particles, the precursor can be in the form of microparticles. For example, Figure 4B A plasma system configuration 410 is shown for sintering or otherwise heating precursor particles 412 (e.g., powder, nanoparticles, elements or compounds carried on a substrate, etc.) to form a particulate product (e.g., powder or nanoparticles). Precursors 402, 412 may be disposed within a gap 306 between a first electrode 302 and a second electrode 304. For example, in some embodiments, the bulk product formed by subjecting precursor 402 to volumetric plasma may be a high-melting-point ceramic (e.g., hafnium carbonitride (Hf-CN)), a refractory metal, or a refractory alloy (e.g., MoNbTaW alloy). For example, in some embodiments, a specific product formed by subjecting precursor 412 (e.g., biomass carbon or carbon black) to volumetric plasma (e.g., at a temperature of 5000 K for 10 seconds) may be carbon nanotubes.

[0117] exist Figures 4A-4B In the example shown, precursors 402, 412 are directly disposed on and supported by a portion of the plurality of first protrusions 114 of the first electrode 302. However, in some embodiments, precursors 402, 412 may be supported within gap 306, for example by a separate support member, to avoid contact with any of the electrodes 302, 304, or to avoid contact only with the second protrusion. In some embodiments, precursors 402, 412 may be placed in gap 306 prior to volumetric plasma initiation. Alternatively, in some embodiments, precursors 402, 412 may be introduced into gap 306 after the volumetric plasma has been initiated and / or stabilized.

[0118] In some embodiments, the system can be configured to deliver the precursor (e.g., along a direction in the xz plane) through gap 306. For example... Figure 4CA flow-through plasma system configuration 420 is shown for sintering or otherwise heating precursor particles 424 (e.g., powder, nanoparticles, elements or compounds carried by a substrate, etc.) to form particulate products 426 (e.g., powder or nanoparticles). The precursor 424 can be carried into and through the gap between the first and second electrodes 302, 304, and / or the product 426 can be carried out from the gap by a carrier gas flow 422 (e.g., an inert gas).

[0119] In some embodiments, the flow-through configuration 420 can replace conventional arc discharge techniques for nanopowder synthesis. For example, an argon gas flow can carry a precursor into and through a volumetric plasma, the temperature of which can be adjusted as needed to obtain the desired nanopowder product. Such nanopowder products may include, but are not limited to, energy storage materials, such as lithium-ion battery cathode powders (e.g., ternary cathode materials, such as nickel-cobalt-manganese) and solid electrolyte powders (e.g., lithium lanthanum-zirconium oxide). Alternatively or additionally, in some embodiments, the flow-through configuration 420 can be used for supported nanoparticle synthesis. For example, a precursor can be pre-dispersed (e.g., coated) on a substrate with a high surface area (e.g., porous microparticles), which is carried through the plasma by a carrier gas 422. The precursor on the substrate can be converted into nanoparticles on the substrate by the plasma.

[0120] In some embodiments, Figure 4C The flow-through configuration can replace traditional methods (e.g., sol-gel treatment, carbothermal reduction, mechanochemical synthesis, etc.) for the synthesis of ultra-high temperature ceramics (UHTCs) (e.g., with melting points above 3000 K), such as high entropy (HE) UHTCs, such as HE-carbides, HE-borides, or HE-nitrides. For example, precursor powders (e.g., carbon black, boron carbide, and / or MO2, where M refers to a transition metal) can be mixed and flow through a volumetric plasma at ultra-high temperatures (e.g., at least 3000 K) via a carrier gas. For HE-UHTCs, the precursor powders can include four or five powder components in substantially equal molar amounts. For example, HE-UHTC precursor powders can include, but are not limited to: carbides (e.g., hafnium carbide, tantalum carbide, zirconium carbide, niobium carbide, titanium carbide) and nitrides (e.g., hafnium nitride, tantalum nitride, zirconium nitride, niobium nitride, titanium nitride). In some embodiments, the composition of the carrier gas can be varied, for example, from pure argon (or other inert gas) to a combination of argon with hydrogen, carbon monoxide, hydrogen, etc., depending on the chemical composition of the target UHTC powder. The reaction temperature can be adjusted by the applied current, the gap distance between the electrodes, and / or the gas pressure. The pre-mixed raw material powder can pass through an ultra-high temperature zone generated by volumetric plasma, and the resulting powder can be collected after exiting the gap.

[0121] exist Figure 4C In the example shown, a carrier gas is used to transport the precursor through the gap between the electrodes and through the plasma between the electrodes. However, other methods for transporting the precursor are possible according to one or more contemplated embodiments. In some embodiments, gravity can be used to transport the precursor through the plasma in addition to or instead of a carrier gas flow, for example, by making the thickness direction of the gap at a non-zero angle relative to gravity (e.g., making the xz plane not perpendicular to gravity). For example, Figure 4E A gravity-feed plasma system configuration 440 is shown for sintering or otherwise heating precursor particles 442 (e.g., powder, nanoparticles, elements or compounds carried by a substrate, etc.) to form particulate products 444 (e.g., powder or nanoparticles). Figure 4E In the example shown, the gap extends substantially parallel to the direction of gravity; however, in some embodiments, the lateral extension of the gap may be at an angle relative to gravity, for example, as shown. Figure 4F The configuration 450 is shown. In either case, gravity can be used to move the precursor 442 into and through the gap between the first electrode 302 and the second electrode 304, and / or remove the product 444 from the gap.

[0122] In some embodiments, Figure 4E or Figure 4F Gravity-feed configurations can replace conventional rotary kiln technology for cement powder synthesis. For example, precursor powders (e.g., limestone, shale, sandstone, or clay, and / or iron oxide) can be mixed and transported via volumetric plasma between electrodes 302 and 304. In some embodiments, the use of high-temperature plasma can remove impurities (e.g., fuel combustion residues) that may occur in conventional processing techniques. Furthermore, because plasma can generate ultra-high temperatures (e.g., ≥3000 K) far exceeding those of conventional rotary kilns (e.g., about 1723 K), cement powder can form large clinker in a much shorter time than required by a rotary kiln (e.g., at least 30 minutes). In some embodiments, the limited-time high-temperature exposure provided by volumetric plasma can selectively transform only the surface of limestone (e.g., forming 3CaO SiO2, 2CaO SiO2, and 3CaO Al2O3), while the core portion of limestone can still retain CaCO3 (e.g., to reduce CO2 emissions).

[0123] In some embodiments, the system may include means for adjusting the size of the generated particles after exposure to volumetric plasma. For example, Figure 4GA plasma system configuration 460 for gravity feeding of precursor particles 462 (e.g., fine powder or nanoparticles) to form particulate product 464 is shown. Similar to the example above, gravity can be used to move the precursor 462 into and through the gap between the first and second electrodes 302, 304, and / or remove the product 464 from the gap. The system configuration 460 also includes a gas flow duct 466 (e.g., an injector) that guides and / or concentrates a gas flow (e.g., an inert gas) at the departing product 464, for example, to break the product 464 (e.g., droplets that have not yet had the opportunity to solidify) into smaller particles 468 (e.g., atomization).

[0124] In some embodiments, Figure 4G Gravity-feed configurations can be used to synthesize atomized high-entropy refractory alloy (RHEA) powders from fine refractory powder feedstocks. For example, the feedstock for volumetric plasma can include micron-sized powders composed of a single refractory metal component. The powder is melted and alloyed as it passes through the ultra-high temperature zone provided by the volumetric plasma. The molten and alloyed RHEA stream exits the volumetric plasma and is then exposed to a high-speed gas jet (e.g., argon and / or helium), which breaks the stream into small droplets. The size of these droplets can be adjusted, for example, by adjusting the gas composition, pressure, etc., to meet the dimensional requirements of additive manufacturing.

[0125] In the examples above, volumetric plasma is used to convert solid precursors into solid products. However, embodiments of the disclosed subject matter are not limited thereto. Instead, the high temperatures provided by volumetric plasma can be used with other material phases, for example, to promote (e.g., catalyze) chemical reactions of gases, either without or with a separate catalyst (e.g., to help guide reaction selectivity). For example, Figure 4D A plasma system configuration 430 for gas phase processing is shown, wherein one or more reactants 432 are converted into one or more products 434, in particular by exposing reactants 432 to high temperatures (e.g., at least 1000 K) using a volume plasma between electrodes 302, 304.

[0126] In some embodiments, Figure 4D The gas-phase treatment configuration can be used to provide CO2 reduction, for example, to recover CO2 from the exhaust gas of combustion products. For example, a mixture of CO2 and water vapor (H2O) can be heated by volumetric plasma to convert the mixture into hydrocarbon fuels, such as methane or acetaldehyde. In some embodiments, Figure 4D The gas-phase processing configuration can be used for the synthesis of ammonia (NH3). For example, a mixture of nitrogen (N2) and hydrogen (H2) can be heated by volumetric plasma to convert the mixture into ammonia. Alternatively, in some embodiments, Figure 4DThe gas-phase processing configuration can be used to decompose ammonia, for example, to form nitrogen and hydrogen. Other synthetic and / or decomposition reactions are also possible according to one or more of the intended embodiments.

[0127] In the examples above, the gap between the electrodes has a generally planar geometry. However, other shapes and configurations are possible according to one or more contemplated embodiments. Indeed, in addition to being a simple method for generating stable and large-area plasmas, embodiments of the disclosed subject matter are scalable and readily adaptable to different manufacturing needs. In some embodiments, the electrodes may be arranged in a coaxial configuration, and the resulting gap may be non-planar. For example… Figures 4H-4I A coaxial plasma system configuration 470 is shown, having an outer annular electrode 472 (e.g., a tube) and an inner rod-shaped electrode 474 disposed within the outer annular electrode 472 and arranged coaxially, thereby forming an annular gap 476 between the outer annular electrode 472 and the inner rod-shaped electrode 474. In the illustrated example, multiple protrusions 479 (labeled 477) cover the surfaces of the two electrodes 472, 474, thereby forming a long volumetric plasma channel. Due to the relatively enclosed environment (e.g., the gap is surrounded by the outer electrode except at opposite axial ends), this configuration is particularly suitable for gas-phase reactions, alloying of refractory metals, and / or various atomization processes, such as where the feedstock enters the gap 476 at one axial end and passes through the plasma channel to subject the material to heating and / or the field effect of the plasma, and the resulting product exits the gap 476 at opposite axial ends 478.

[0128] Alternatively or additionally, in some embodiments, the electrodes may be configured to confine the generated plasma to a small area, for example, to form a focused heating zone. Figures 4J-4KAnother coaxial plasma system configuration 480 is shown, but with a focused heating zone 488. In the illustrated example, system configuration 480 includes an inner rod-shaped electrode 484 (e.g., a carbon felt rod) and an outer electrode 482 (e.g., a graphite shell), the inner rod-shaped electrode 484 disposed within the outer electrode 482 and both arranged coaxially. Electrodes 482, 484 form a narrow annular gap 486 near the focused heating zone 488, while the spacing between the electrodes (e.g., radially) is sufficiently large away from the heating zone, such that plasma forms only near the heating zone 488. This configuration can help improve the processing accuracy of the generated plasma, for example, for additive manufacturing (3D printing on a substrate 490). In the illustrated example, a plurality of first protrusions 492 (e.g., short carbon fibers) and a plurality of second protrusions 494 (e.g., long carbon fibers) extend from the covered surface of the inner electrode 484, while the outer electrode 482 presents only an exposed surface without any protrusions. For example, at least a portion of the second protrusions 494 may contact the outer electrode 482 to help initiate plasma formation.

[0129] In any of the published examples, in addition to undergoing ultra-high temperatures via volumetric plasma, the system can also provide rapid cooling (e.g., at least 10...). 2 (K / s). In some embodiments, cooling can be provided by shutting off the volumetric plasma, for example, by not providing electrical power to the electrodes or at least providing an electrical power level insufficient to support plasma generation. Alternatively or additionally, cooling can be provided by removing material from the volumetric plasma, for example, by transporting material from within the gap between the electrodes to outside the gap using a carrier gas flow or gravity. Alternatively or additionally, cooling can be provided by removing the volumetric plasma from the material, for example, by moving one or two electrodes relative to the material and / or by changing the position of the generated plasma using a magnetic field. Alternatively or additionally, active cooling forms can be used, such as, but not limited to, directional airflow, heat exchangers, heat pumps, and thermoelectric modules. Other cooling techniques and forms are also possible according to one or more of the contemplated embodiments.

[0130] Example of supporting electrode

[0131] In some embodiments, one or both electrodes may be supported in a movable manner relative to the other, for example, to allow processing of samples larger than the volumetric plasma size. In such embodiments (or in any other embodiments), the area of ​​one electrode (e.g., the area of ​​the surface facing the gap) may be smaller than the area of ​​the other electrode (e.g., the area of ​​the surface facing the gap). In some embodiments, the smaller supporting electrode may be movable relative to the larger electrode, for example, to allow the localized heating zone provided by the generated plasma to move on the surface of the larger electrode. For example, Figure 5A A movable plasma generation system 500 is shown, which can provide volumetric plasma 514 at different locations. In the example shown, the system 500 includes a first electrode and a second electrode, a first translation stage 504a and a second translation stage 504b, a frame 502 supporting the first and second translation stages, a power supply 108, and a controller 110. The first electrode may have a first base layer 506 having a plurality of protrusions 508 extending from itself, and the second electrode may have a second base layer 510 having a plurality of protrusions 512 extending from itself. In the example shown, the first base layer 506 may have an area A1 (e.g., in the xz plane) smaller than the area A2 (e.g., in the xz plane) of the second base layer 510, and the plurality of protrusions 508, 512 may cover the respective areas.

[0132] Translation stages 504a, 504b can be mechanically coupled to the respective substrates 506, 510 and configured to move the respective electrodes in at least one dimension (e.g., in two dimensions, e.g., along the xz plane). In operation, translation stages 504a, 504b can thus move the electrodes relative to each other to change the position of the generated volumetric plasma 514, for example, to scan the heated region on the sample surface on the substrate 510 generated by the plasma. Alternatively, in some embodiments, only one translation stage may be provided to move the electrode coupled thereto, while the other electrode remains substantially fixed (e.g., supported in place by the frame 502). In some embodiments, one or both translation stages 504a, 504b may be configured to move the respective electrode along the y-direction and / or move the respective electrode in three-dimensional directions, for example, to allow for changes in the size of the gap between the electrodes.

[0133] In some embodiments, the volumetric plasma is moved by shifting one of the two electrodes or both electrodes relative to the other electrode. This can be used in additive manufacturing, for example, to achieve powder bed melting or sintering. Figure 5BA configuration of a plasma system 520 for additive manufacturing is shown. System 520 includes a support electrode head 522 (e.g., a carbon felt disc with a diameter of 10 mm) and a base electrode strip 524. A powder bed 528 may be disposed on and supported by the base electrode strip 524. In some embodiments, the powder bed 528 comprises a conductive material, such as pre-pressed sample particles derived from multi-element metal powder. A plasma beam 526 (e.g., having a column radius of approximately 1 mm) can be generated by applying a voltage between the support electrode head 522 and the base electrode strip 524. Either or both of the support electrode head 522 and the base electrode strip 524 can be moved relative to the other (e.g., using an electric platform) to scan the plasma 526 across the powder bed 528.

[0134] More details on operating System 520 are available in [link / details]. Figure 5C As shown in the diagram. In the initial positioning phase 530, the supporting electrode head 522 moves over a portion of the base electrode strip 524 exposed from the powder bed 528, such that the array 534 and the array 538 of the first protrusions of the electrodes face each other. In the example shown, the electrodes also have corresponding second protrusions 540, 542, which, in the positioning phase 530, may form a contact 548, or at least have a narrow gap between them. Then, during the plasma initiation phase 546, the voltage between the electrodes increases to induce a gas discharge, for example, between the second protrusions 540, 542, which then diffuses and stabilizes into the columnar plasma 526 by means of the first protrusions 534, 538 in the plasma stabilization phase 550. Once the columnar plasma 526 is formed, one or both electrodes can be moved relative to the other electrode to position a portion of the powder bed 528 within the plasma 526. During the sintering stage 554, plasma 526 can move on the surface of powder bed 528 to sinter or melt different parts of powder bed 528.

[0135] In some embodiments, such as when the electrode is formed of fabric or felt, the configuration of the supporting electrode may include one or more retainers to hold, shape, increase mechanical strength or stiffness, and / or make electrical connections to the electrode. For example, Figures 5D-5EA configuration 560 for supporting electrodes is shown, wherein electrodes 564a and 564b are spaced apart from each other by a gap 568. The surface portion of each electrode 564a and 564b facing the gap 568 may each have multiple protrusions 566a and 566b, similar to the example described above. A portion of electrode 564a opposite to the gap 568 can be inserted into and held by electrode holder 562a, and a portion of electrode 564b opposite to the gap 568 can be inserted into and held by electrode holder 562b. Electrode holders 562a and 562b can be electrically coupled to power supply 108 via corresponding electrical coupling members 572a and 572b (e.g., clamps fixed to the outer surface of the holders).

[0136] In some embodiments, the holders 562a, 562b and electrodes 564a, 564b may be formed of a conductive material with a melting temperature greater than or equal to 1000 K. Alternatively, in some embodiments, electrodes 564a, 564b may be formed of a conductive material with a melting temperature greater than or equal to 1000 K, and holders 562a, 562b may be formed of a conductive material with a melting temperature less than 1000 K. Power from power source 108 may be supplied to electrodes 564a, 564b to generate plasma within gap 568 via electrode holders 562a, 562b and corresponding coupling members 572a, 572b. In the illustrated example, each electrode holder 562a, 562b is a U-shaped member, although other shapes are possible according to one or more contemplated embodiments. In some embodiments, electrodes 564a, 564b may be formed of flexible or fluffy materials, such as carbon felt or carbon fabric, and electrode holders 562a, 562b may be formed of more rigid materials, such as machined graphite, 3D printed carbon, refractory metals, etc.

[0137] In the illustrated example, each electrode holder 562a, 562b is also provided with a corresponding base member 570a, 570b. In some embodiments, the base members 570a, 570b (e.g., feet) may be formed of an electrically insulating material (e.g., ceramic) and may be configured to support the electrode holder (and the electrodes supported thereon) in a substantially vertical direction (e.g., gravity feed configuration). In such an embodiment, region 574 on the side of gap 568 opposite to base members 570a, 570b can be considered an input region (e.g., for supplying precursors, reactants, or other materials to be treated by plasma), and region 576 on the same side of gap 568 as base members 570a, 570b can be considered an output region (e.g., where products or processed materials exit the plasma). In some embodiments, one or more components may be disposed within a capture region 578 below or near the output region 576 to capture exiting products or processed materials.

[0138] According to one or more of the intended embodiments, other configurations are also possible. For example, in some embodiments, the input and output areas may be located in... Figure 5D The gap 568 in the plan view is on the opposite side, not located on the opposite side. Figure 5E The opposite sides of gap 568 in the front view. Alternatively or additionally, in some embodiments, the input region and the output region may be the same region, for example, the material may exit gap 568 in the same direction and through the same end into which the material enters. Alternatively or additionally, in some embodiments, the output region may be in a direction orthogonal to the input region (for example, the input may be located on the top side of gap 568, while the output exits via the lateral side of gap 568, rather than (or except) via the bottom of gap 568).

[0139] Figure 5F Other aspects of a plasma generation system 580 are shown, which employs electrode holders 562a, 562b, for example, to process precursors or particles fed from an input hopper 592. In the illustrated example, electrode holders 562a, 562b may have thickened bottom portions 586a, 586b, for example, to help increase the stability and / or rigidity of the upright holder. Base members 570a, 570b of electrode holders 562a, 562b may also be disposed within a recess 588 of an insulating holder 584 (e.g., formed of plastic or ceramic), for example, to help hold the holder in an upright orientation. In some embodiments, the profile of the inlet region 574 may differ from the profile of the rest of the gap 568, for example, to deliver particles / reactants to the plasma and / or to prevent plasma formation in the inlet region. For example, electrodes 564a, 564b may include corresponding inclined surface portions 582a, 582b to form a tapered inlet region. Alternatively or additionally, in some embodiments, a collection member 590 (e.g., a substrate or hopper) may be supported on base members 570a, 570b and disposed within a capture zone 578, for example, to collect the processed material and plasma therein exiting the gap 568.

[0140] Example methods for volumetric plasma generation and use of volumetric plasma

[0141] Figure 6A Aspects of a method 600 for generating and using volumetric plasma are illustrated. Method 600 may initiate a processing step 602, in which a pair of electrodes may be provided. In some embodiments, one or both electrodes provided may have multiple short protrusions, for example, having those described herein. Figures 1A-5FAny first protrusion discussed in any of the figures. In some embodiments, one or both electrodes provided may have at least one long protrusion, for example, having the features discussed herein. Figures 3A-3F and Figures 4A-5F Any second protrusion discussed in any of the figures. In some embodiments, providing processing step 602 may include manufacturing an electrode or electrode portion, for example, forming short and / or long protrusions. For example, short and / or long protrusions may be manufactured by 3D printing (e.g., laser-based direct energy deposition or laser powder bed melting). Alternatively or additionally, in some embodiments, short and / or long protrusions may be manufactured by cutting fabric or felt, for example, formed from a refractory material (e.g., carbon, refractory metal, or refractory metal alloy). Alternatively or additionally, in some embodiments, short and / or long protrusions may be manufactured by grinding or roughening the surface of a refractory material (e.g., fabric or felt).

[0142] Method 600 can proceed to determination step 604, in which plasma can be initiated between the electrodes. In some embodiments, when long protrusions are provided on one or both electrodes, plasma can be initiated via option 606a, wherein the long protrusions are subjected to Joule heating to create a narrow gap between the long protrusions, and then a spark discharge occurs between the narrow gaps. For example, initiating plasma using long protrusions via option 606a can be similar to the description herein. Figures 3A-3F Any of those discussed herein. Alternatively or additionally, in some embodiments, the plasma can be initiated via option 606b, in which the gap thickness can be reduced to allow spark discharge between the electrodes, such as between short protrusions. For example, initiating the plasma using a reduced gap thickness via option 606b can be similar to that discussed herein. Figure 3H and Figures 5A-5C Any of those discussed. Alternatively or additionally, in some embodiments, the plasma can be initiated by any other technique 606c, such as, but not limited to, applying a higher breakdown voltage, changing the gas pressure, and / or using a separate trigger (e.g., as discussed herein). Figure 3G (As discussed).

[0143] Method 600 may proceed to processing step 608, in which volumetric plasma may be maintained. In some embodiments, processing step 608 may include, for example, growing an initiated plasma on the electrode surface via short protrusions to form a volumetric plasma. In some embodiments, the volumetric plasma may be substantially spatially homogeneous and / or time-stable. In some embodiments, processing step 608 may include applying a DC voltage, AC voltage (e.g., RF), or pulsed voltage waveform (e.g., square wave) of sufficient power to the electrodes to maintain the plasma between the electrodes. In some embodiments, the plasma temperature and / or the temperature distribution of the volumetric plasma may be substantially constant for at least one minute, for example, substantially constant for at least ten minutes. In some embodiments, maintaining processing step 608 may include changing the power applied to the electrodes, changing the gap thickness between the electrodes, and / or changing the gas pressure between the electrodes, for example, to change the plasma temperature. Alternatively or additionally, maintaining processing step 608 may include moving the volumetric plasma, for example, to expose materials to the plasma (e.g., as described herein). Figures 5A-5C (Any of those discussed).

[0144] Method 600 can proceed to step 610, in which volumetric plasma can be used, for example, in a manner similar to that described herein. Figures 4A-4K and Figures 9A-11 Volumetric plasma is used in any of the ways discussed. For example, volumetric plasma can be used to heat materials, such as, but not limited to, sintering particles to form bulk materials, heating stationary or flowing particles to form alloys, cement, or ceramics (e.g., nanopowders or supported nanoparticles), heating stationary or flowing particles to form other particles (e.g., carbon nanotubes), heating stationary or flowing particles to form surface layers (e.g., powder bed melting), promoting thermochemical reactions (e.g., chemical synthesis or degradation, with or without catalysts), performing cryogenic sterilization, or for any other purpose.

[0145] Although steps 602-610 of method 600 have been described as being performed once, in some embodiments, a particular processing step may be repeated multiple times before proceeding to the next decision block or processing step. Furthermore, although steps 602-610 of method 600 have been shown and described separately, in some embodiments, the processing steps may be combined and executed together (either simultaneously or sequentially). Moreover, although... Figure 6A A specific order of steps 602-610 is shown, but embodiments of the disclosed subject matter are not limited thereto. In fact, in some embodiments, these steps may occur in a different order than shown, or simultaneously with other steps. In some embodiments, method 600 may include steps not shown in... Figure 6A The steps or other aspects specifically illustrated herein. Alternatively or additionally, in some embodiments, method 600 may include only the steps shown. Figure 6A Steps 602-610 are part of steps 602-610.

[0146] Computer implementation example

[0147] Figure 6B A general example of a suitable computing environment 631 is depicted, in which the described innovations can be implemented, such as, but not limited to, aspects of the power supply 108, controller 110, control system 124, controller of translation stage 372, and / or method 600. The computing environment 631 is not intended to impose any limitations on its scope of use or functionality, as these innovations can be implemented in a variety of general-purpose or special-purpose computing systems. For example, the computing environment 631 can be any of a variety of computing devices, such as desktop computers, laptop computers, server computers, tablet computers, etc.

[0148] refer to Figure 6B The computing environment 631 includes one or more processing units 635, 637 and memories 639, 641. Figure 6B In this diagram, this basic configuration 651 is enclosed within the dashed lines. Processing units 635 and 637 execute computer-executable instructions. The processing units can be central processing units (CPUs), processors in application-specific integrated circuits (ASICs), or any other type of processor (e.g., hardware processors, graphics processing units (GPUs), virtual processors, etc.). In a multiprocessor system, multiple processing units execute computer-executable instructions to increase processing power. For example, Figure 6B A central processing unit 635 and a graphics processing or coprocessing unit 637 are shown. Physical memories 639 and 641 may be volatile memories (e.g., registers, caches, RAM), non-volatile memories (e.g., ROM, EEPROM, flash memory, etc.), or some combination of both, accessible to the processing unit. Memories 639 and 641 store software 633 implementing one or more innovations described herein in the form of computer-executable instructions suitable for execution by the processing unit.

[0149] The computing system may have other features. For example, computing environment 631 includes storage 661, one or more input devices 671, one or more output devices 681, and one or more communication connections 691. Interconnection mechanisms (not shown), such as buses, controllers, or networks, interconnect the components of computing environment 631. Typically, operating system software (not shown) provides an operating environment for other software executing in computing environment 631 and coordinates the activities of the components of computing environment 631.

[0150] Physical storage 661 may be removable or non-removable and includes disks, magnetic tapes or cassettes, CD-ROMs, DVDs, or any other medium that can be used to store information in a non-transitory manner and can be accessed within computing environment 631. Storage 661 may store instructions for implementing one or more of the innovative software 633 described herein.

[0151] Input device 671 may be a touch input device such as a keyboard, mouse, pen, or trackball, a voice input device, a scanning device, or another device that provides input to computing environment 631. Output device 681 may be a monitor, printer, speaker, CD burner, or another device that provides output from computing environment 631.

[0152] Communication connection 691 allows communication with another computing entity via a communication medium. The communication medium carries information, such as computer-executable instructions, audio or video input or output, or other data in a modulated data signal. A modulated data signal is a signal whose one or more characteristics are set or altered in a manner that encodes information in the signal. By way of example and not limitation, the communication medium may be electrical, optical, radio frequency (RF), or other carriers.

[0153] Any disclosed method can be implemented as computer-executable instructions stored on one or more computer-readable storage media (e.g., one or more optical media disks, volatile memory components (e.g., DRAM or SRAM), or non-volatile memory components (e.g., flash memory or hard disk)) and executed on a computer (e.g., any commercially available computer, including smartphones or other mobile devices that include computing hardware). The term computer-readable storage media excludes communication connections such as signals and carrier waves. Any computer-executable instructions used to implement the disclosed technology, as well as any data created and used during the implementation of the disclosed embodiments, can be stored on one or more computer-readable storage media. The computer-executable instructions can be, for example, part of a dedicated software application, or part of a software application accessed or downloaded via a web browser or other software application (such as a remote computing application). Such software can be executed, for example, on a single local computer (e.g., any suitable commercially available computer) or in a network environment using one or more networked computers (e.g., via the Internet, a wide area network, a local area network, a client-server network (e.g., a cloud computing network), or any other such network).

[0154] For clarity, only certain selected aspects of the software-based implementation are described. Other details well-known in the art have been omitted. For example, it should be understood that the disclosed techniques are not limited to any particular computer language or program. For instance, aspects of the disclosed techniques can be implemented using C++, Java, etc. TMThis is implemented using software written in Python® and / or any other suitable computer language. Similarly, the disclosed techniques are not limited to any particular computer or hardware type. Certain details of suitable computers and hardware are well known and do not need to be elaborated in this disclosure.

[0155] It should also be clearly understood that any functionality described herein may be performed, at least in part, by one or more hardware logic components rather than by software. Examples of hardware logic components that may be used include, but are not limited to, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip (SoCs), complex programmable logic devices (CPLDs), etc.

[0156] Furthermore, any software-based implementation (including, for example, computer-executable instructions for causing a computer to perform any of the disclosed methods) can be uploaded, downloaded, or remotely accessed via suitable communication means. Such suitable communication means include, for example, the Internet, the World Wide Web, an intranet, software applications, cable (including fiber optic cables), magnetic communication, electromagnetic communication (including RF, microwave, and infrared communication), electronic communication, or other similar communication means. In any of the foregoing examples and embodiments, providing requests (e.g., data requests), indications (e.g., data signals), instructions (e.g., control signals), or any other communication between systems, components, devices, etc., can be achieved by generating and transmitting appropriate electrical signals via wired or wireless connections.

[0157] Examples of manufacturing and experimental results

[0158] like Figure 7B As shown, the plasma generation device 700 consists of two carbon felt electrodes 706a and 706b connected to graphite holders 702a and 702b. To manufacture the electrodes, a piece of carbon felt measuring 50mm × 150mm × 6.5mm is stamped into a disk with a diameter of 25.4mm. Then, approximately 1mm is cut from the felt surface with a blade, cutting the carbon fibers that make up the felt and generating vertically oriented carbon fiber tips. Two circular graphite blocks measuring 50mm × 50mm × 25mm are machined using a computer numerical control (CNC) machine tool to serve as holders for the carbon felt electrodes. The graphite holders 702a and 702b are connected to the positive and negative tabs of a programmable power supply via copper wires 704a and 704b. The gap 708 between the two electrodes 706a and 706b is set to approximately 3mm, but can be adjusted for different applications. The entire electrode assembly 700 is housed in a glove box filled with pure argon gas at atmospheric pressure. In this setup, multiple long carbon fibers (loosened through an electrode cutting process) extend from the surface of the carbon felt and form a contact between the two electrodes, such as... Figure 7CAs shown. Furthermore, the electrode surface generated by cutting the carbon felt has a high density of short, vertically oriented carbon fibers with blunt tips, which are separated by uncut, horizontally aligned fibers with an inter-bundle distance of approximately 200 μm, as... Figures 7C-7D As shown, the carbon fiber tip has a diameter of approximately 10 μm, which is much smaller than the micrometer to centimeter scale of metal needle electrodes traditionally used to generate arc plasma.

[0159] To initiate the plasma, the voltage between electrodes 706a and 706b is gradually increased (e.g., up to approximately 33V). The longer fibers in contact with each other generate intense Joule heating, causing the fibers to glow. The resistance at defective regions or contacts between fibers is higher than the resistance of the fibers themselves, causing localized heating at the fiber joints. At higher currents, excessive Joule heating generates extremely high temperatures, causing the fibers to break and forming small gaps between the long fibers, thus breaking the circuit. These small gaps (e.g., about a few micrometers) significantly reduce the gas breakdown voltage (e.g., about 42V) and increase the homogeneity of the plasma through an enhanced electric field and increased secondary electron emission at the fiber tips. Once a spark is formed and the plasma is initiated, a gas discharge propagates between the electrodes, attributable to the shorter, vertically aligned array of fiber bundles that generates a concentrated electric field that coalesces at the electrode surfaces. Therefore, this unique tip-enhanced electrode design allows for a smooth transition to volumetric arc discharge. The generated plasma produces extremely bright light, requiring a neutral density filter for clear observation. Interestingly, as... Figure 7D As shown, the carbon fibers exhibit sharper tips after the plasma generation process, and these tips are retained even 10 minutes after plasma discharge. The carbon tips may become sharp due to the concentrated electric field generated when a voltage is applied between the two electrodes. This sharpness can further increase the surrounding local electric field and promote the discharge process.

[0160] like Figure 7A As shown, continuous volumetric plasma (e.g., approximately 25 mm in diameter, but limited only by electrode size) exhibits a highly controllable temperature range of 3000-8000 K, along with a uniform temperature distribution. Compared to conventional arc jet or needle-type arc plasma technologies, device 700 can achieve plasma over a uniform large area and at relatively high temperatures under atmospheric pressure with a moderate current input (e.g., approximately 45 A). Notably, due to the low heat capacity, high thermal conductivity, and high emissivity of the carbon electrodes, the carbon fiber tips remain stable even under these ultra-high temperature conditions. Therefore, under continuous power input, the volumetric plasma can maintain stable operation for 10 minutes or longer.

[0161] The temperature of the plasma was determined using Rayleigh thermometry, a linear technique in which the Rayleigh scattering signal is directly proportional to the total density of molecules in the plasma and inversely proportional to the temperature. Figure 7E As shown, as the current increases from 15A to 45A (corresponding to a current density of 3A / cm²), 2 Up to 9A / cm 2 At this temperature, the plasma temperature increased from approximately 4200 K to approximately 7700 K. This demonstrates that the device can generate an ultra-high temperature environment with precise temperature control. Temperature was also verified by line scanning measurements of the plasma center at a current of 20 A (4 A / cm²), showing an electrode surface temperature of approximately 4700 K, thus confirming the homogeneity of the plasma. Further measurements were taken under the same conditions (4 A / cm²). 2 The plasma temperature (with a gap of approximately 3 mm) was measured using gray-body radiation spectroscopy, yielding an average temperature of approximately 4500 K, validating the Rayleigh temperature determination method. Despite the extremely high plasma temperature, numerical simulations showed a low temperature distribution at the carbon tip; even with the plasma center set to 7000 K, the carbon tip temperature only reached approximately 3000 K. This can be attributed to the high thermal conductivity and emissivity of the carbon tip, which facilitates rapid heat transfer from the electrodes. This also explains why the carbon tip can remain stable in such an ultra-high temperature environment, essential for the continuous operation of the plasma.

[0162] To investigate the role of fibers in the plasma breakdown process, control experiments were conducted using stainless steel electrodes without any fibers. These plate electrodes required approximately 1500V to achieve gas discharge breakdown at a gap of about 3mm, which is more than 30 times higher than the 42V required using carbon fiber tip-reinforced electrodes at the same electrode gap distance. For the disclosed device, the significant reduction in breakdown voltage can be attributed to the presence of both long and short carbon fiber tips that enhance the electric field. The long carbon fibers provide the small gap distance through Joule heating fracture, while the tips of the short carbon fibers enhance the electric field, promoting Townsend breakdown. Furthermore, the short fiber tips enhance secondary electron emission, enabling the formation of a volumetric spark discharge with a uniform temperature distribution. In contrast, the stainless steel plate electrodes lack both sharp fiber tips for enhancing the electric field and short tips for promoting secondary electron emission, thus requiring much higher voltages to achieve gas discharge breakdown and making it difficult to generate uniform volumetric plasma. Moreover, when using fiber-free stainless steel-stainless steel plate electrodes, the discharge location is very narrow and unpredictable, typically developing along the path of a streamer discharge, which may make this configuration unsuitable for material fabrication requirements. In contrast, the short fiber tip array of the disclosed device is capable of forming volumetric plasma through a locally enhanced electric field at the tip, which causes gas discharges between the electrodes to fuse.

[0163] Control experiments were also conducted by isolating the effects of long and short carbon fibers in the disclosed setup. In some cases, plasma breakdown could not be generated under the same conditions by removing the long fibers between the carbon felt electrodes and ensuring no contact was formed. However, higher breakdown voltages and / or other plasma-initiating techniques could be used instead of long carbon fibers. Furthermore, to investigate the effect of an array of short fiber tips, two graphite plate electrodes of the same size were used, but only a bundle of long fibers was bonded between the electrodes. These control electrodes initially showed phenomena similar to those of the carbon felt electrodes, where sparks formed after a dark period. However, as the voltage continued to increase, only spark discharges were observed, without continuous or expanding plasma formation. In contrast, the disclosed device was able to generate stable volumetric plasma due to the dense short carbon fibers on the surface of the decorative electrodes.

[0164] Figure 3D The current-voltage (CV) characteristics of the disclosed plasma discharge process using tip-enhanced carbon felt electrodes are shown. The plasma electric field strength between the electrodes is simultaneously measured using the in-situ electric field-induced second harmonic (E-FISH) method, and the results are presented in… Figure 8A As shown in the diagram. Conceptually, E-FISH measures the electric field by the second harmonic signal of the excited laser in the presence of an applied electric field. The second harmonic signal is proportional to the square of the plasma electric field strength. To determine the final electric field, the E-FISH signal is calibrated by measuring the electric field generated before breakdown using a DC power supply, and Rayleigh scattering is used to correct for the molecular number density. The spatial resolution of the E-FISH measurement along the laser beam propagation direction is approximately 3 mm (estimated based on the confocal length of the laser beam).

[0165] refer to Figure 3D When the bias voltage of the top carbon felt (cathode) is increased from zero to approximately 33V (first stage 320), bright filaments are observed between the electrodes. These filaments are long carbon fibers in contact with each other and are thus Joule-heated as current flows through them. Then, when the voltage is increased from approximately 33V to approximately 42V, no current signal is observed in the CV curve (second stage 322), and no light emission from the optical fiber is observed. This lack of current can be attributed to the high temperatures experienced by the fibers in the first stage 320 due to Joule heating, causing them to physically break in high-resistance regions (e.g., interfiber connections) and forming narrow gaps between these long fibers. These gaps between the long fibers prevent the Joule heating effect, causing the fibers to darken again.

[0166] As the voltage further increases to approximately 42-45 V (stage 3, 324), the electric field increases further, and spark discharge is observed. This discharge occurs in the narrow gap between the fractured fibers through a tip-enhanced field emission effect. This discharge process can promote electron collisional ionization via Townsend avalanche, helping to reduce the plasma breakdown voltage and thus igniting the plasma (stage 4, 326). With this transition to arc discharge, due to the increase in electron number density and conductivity of the plasma gas (stage 5, 328), a rapid drop in voltage to approximately 20 V and a current surge to 18 A (i.e., the arc discharge breakdown current) are observed. After breakdown, the electric field between the two electrodes, as measured by E-FISH, remains very low (approximately 5 V / mm), indicating that only a very low electric field is required to sustain the plasma. Subsequently, the arc discharge volume begins to expand rapidly between the electrodes.

[0167] When the current reaches approximately 45 A (stage 6, 330), the plasma generates a temperature of approximately 7700 K. The current is then gradually reduced from 45 A (stage 7, 332). During this stage, even when the current reaches only about 7 A (below the gas discharge breakdown current (approximately 18 A in stage 5, 328)), the arc discharge remains stable (albeit at a lower intensity). This significant hysteresis can be explained by the high electron density between the electrodes once the arc discharge occurs, making it easier to maintain the arc discharge state. Furthermore, the plasma temperature remains high (>3000 K), which promotes thermionic emission of electrons from the tips of the short carbon fibers. However, when the current decreases below 7 A (stage 8, 334), the plasma terminates, and the voltage surges to 42 V, thus closing the hysteresis loop. Overall, the breakdown voltage of the disclosed plasma device is significantly lower than previously reported plasma breakdown values ​​and exhibits high reproducibility (approximately 42 ± 2.6 V based on 15 experiments).

[0168] Volumetric plasmas can also be rapidly switched on and off, for example, by simply adjusting the applied voltage and current. Figure 8B As shown, pulsed plasma can be generated by repeatedly setting the applied voltage to 45V for 0.5 seconds and then restoring it to 0V for 0.5 seconds using a programmable power supply. This process increases the plasma current to 35A within 1 second. Therefore, the plasma temperature can cycle between 1000K and 6000K in less than 1 second, with a heating / cooling rate of approximately 10. 3 K / s. This excellent tunability is attributed to the low voltage barrier of the arc plasma transition achieved by the tip-enhanced electrodes. The disclosed device's ability to rapidly raise the plasma to a high temperature and then quench it back to a low temperature in a pulsed manner allows it to control reaction pathways for various non-equilibrium synthesis processes that require drastic temperature changes, such as rapid cooling.

[0169] This continuous, volumetric, homogeneous, and stable ultra-high temperature plasma can be used to synthesize various high-temperature materials. For example, the disclosed apparatus was used to synthesize and sinter hafnium carbonitride (Hf(C,N)), an ultra-high temperature ceramic that has been difficult to prepare due to its high melting point (>4000K). In the disclosed apparatus, the plasma can reach temperatures of several thousand K in less than one second, preventing nitrogen dissociation, thus successfully synthesizing and sintering Hf(C,N). To study the synthesis of Hf(C,N), a particle prepared by mixing HfC and HfN precursor powders was prepared. Specifically, HfC (99% purity) and HfN (99.5% purity) powders were weighed, with a nominal atomic ratio of Hf:C:N of 0.53:0.27:0.2, then mixed and ball-milled for 5 hours. The tungsten carbide ball mill jar was sealed with tape in an argon atmosphere to prevent oxidation of the powder during grinding. The ball-milled powder was then pressed into particles with a diameter of 10 mm and placed in a container. Figure 7B The particles were heated on the lower electrode surface in the gap region between two tip-reinforced carbon felt electrodes 706a and 706b. A programmable power supply was used to generate plasma, specifically heating the particles for 10 seconds at plasma temperatures of 4400 K, 4500 K, 4800 K, and 5150 K (as measured by Rayleigh scattering). The sintered particles were cooled to room temperature for further characterization.

[0170] When HfC / HfN particles were placed on the bottom carbon felt electrode 706b, the temperature distribution of the generated plasma under different currents was consistent with the plasma temperature without particle samples. The phase and structure of the sintered ceramic particles generated via plasma sintering were investigated. Before sintering, the cross-section of the precursor particles exhibited a compacted powder structure. After a one-step plasma sintering process at a plasma temperature of 5150 K for approximately 10 seconds, the resulting ceramic particles showed good density and uniformity in cross-section. Figure 9A The X-ray diffraction (XRD) patterns of the obtained Hf(C,N) samples are shown. Following synthesis, a predominantly single-phase rock salt crystal structure (space group: Fm) was successfully obtained. These results demonstrate that, in the disclosed apparatus, the ultra-high temperature of the plasma can rapidly synthesize and sinter Hf(C,N), which is predominantly a single phase, within just 10 seconds.

[0171] The disclosed plasma device also possesses rapid quenching capabilities, where the temperature can drop from 6000K to 1000K in less than one second. This rapid quenching capability can be used to synthesize bulk extreme materials, such as, but not limited to, amorphous high-melting-point oxides, which typically require rapid quenching after melting to obtain the desired disordered state. Due to the simultaneous need for high-temperature melting and rapid cooling, most high-melting-point oxide materials are also extremely difficult to transform into amorphous forms using conventional tools. The amorphous phases of ultra-high-temperature oxides, such as magnesium oxide (MgO), are usually produced by sputtering into thin films rather than as bulk materials.

[0172] As an example, the disclosed plasma heating and quenching method was applied to crystalline MgO powder. Specifically, crystalline MgO oxide powder (>99% purity) was pressed into particles with a diameter of 8 mm. After plasma initiation, the particle sample was inserted into the gap region between two carbon felt electrodes 706a and 706b and heated to approximately 6000 K for 20 seconds until the particles melted. The plasma was then shut off, the sample was rapidly removed with a ceramic plate, and cooled to room temperature within seconds by a strong gas flow. This rapid cooling process helped maintain the spherical morphology formed by surface tension in the molten state. Figure 9B The XRD pattern of the obtained MgO is shown, in which no sharp peaks were detected, indicating the formation of an amorphous MgO phase. Cross-sectional imaging analysis of the MgO sample showed no obvious grain boundaries. The disclosed plasma heating and quenching can be applied to other oxides with high melting points (e.g., >3000 K). Similar results were obtained, for example, using zirconia (ZrO2) crystalline oxide powder (99% purity) and yttrium-stabilized zirconia (YSZ) crystalline oxide powder (TZ-3Y).

[0173] The disclosed plasma apparatus can also be used to synthesize tungsten-based refractory alloys directly from metallic element powders. For example, a W-1.5Nb-0.5Ti alloy was designed, in which tungsten (W) is used as the main refractory metal, and the lower melting points of niobium (Nb) and titanium (Ti) help promote sintering. Specifically, tungsten (99.95% purity), niobium (99.85% purity), and titanium (99.98% purity) powders were mixed with a nominal composition of 98 wt.% W, 1.5 wt.% Nb, and 0.5 wt.% Ti. The powder mixture was further mixed in a roller mixer for 5 hours to achieve high homogeneity. The powder mixture was then printed into a planar rectangular shape of 1×8×30 mm using a binder jetting method (ExOne™ Innvent+®, sold by Desktop Metal, Inc. of Burlington, MA, USA). A set of standard printing parameters for the tungsten alloy was selected for the printing process (e.g., saturation: 60%; binder setting time: 5s; drying time: 10s; layer thickness: 50μm; coarse grinding roller: 300rpm; smoothing roller: 400rpm). To minimize carbon contamination during printing, a low-carbon binder was used. After printing, the samples were cured in an oven at 200°C for 8 hours to enhance their strength and facilitate subsequent powder removal and processing. After removing excess powder with compressed air, the samples underwent a 30-minute binder removal step at 450°C, specifically decomposing the binder into evaporated organic fumes, leaving a shaped powder mixture (e.g., particles), which was then sintered using the disclosed plasma apparatus.

[0174] Particles were placed on the surface of the lower electrode 706b, and plasma was generated within the gap 708 using a programmable power supply. The generated plasma heated the particles for 10 seconds at a plasma temperature of approximately 4700 K (measured by Rayleigh scattering). The sintered particles were then cooled to room temperature for further characterization. Imaging and energy-dispersive X-ray spectroscopy (EDS) mapping results showed that the applied plasma treatment formed a dense W-1.5Nb-0.5Ti alloy with a uniformly distributed W / Nb / Ti elemental composition. Furthermore, the elemental ratios of the synthesized sample were consistent with those of the precursor, indicating that the rapid plasma heating process minimized (or at least reduced) elemental evaporation.

[0175] For comparison, samples with the same composition (98W-1.5Nb-0.5Ti (wt.%)) were synthesized using a conventional arc melting method. Specifically, raw materials in pure metallic form with a purity >99.99 wt.% (W: 99.999 wt.%, Nb: 99.999 wt.%, Ti: 99.99 wt.%) were cleaned and weighed, and then placed into the chamber of the arc melter. The chamber was evacuated and purged with pure argon (Ar) until the pressure reached 2 psi. The argon flash evaporation process was repeated four times to ensure an inert environment within the chamber. The open-circuit voltage was 85V, and the current was set to 350A, which are the recommended maximum limits to avoid damage to the tungsten electrode of the arc melter. At the start of the arc melting process, high-purity Zr (>99.99 wt.%) flakes were completely melted to further remove residual oxygen from the chamber. Each melting process lasted approximately one minute, followed by 20 seconds of in-furnace cooling with cold tap water flowing over the copper crucible. The melting process was repeated three times to maximize the homogeneity of the alloy composition. After melting, the samples were cut and polished for microstructural analysis. The resulting samples exhibited significant inhomogeneity and the presence of unmelted tungsten within the microstructure.

[0176] The disclosed plasma apparatus has also been used to synthesize MoNbTaW (equimolar) refractory alloys with similar results, demonstrating the versatility of the disclosed plasma apparatus for synthesis / sintering. Specifically, with Mo... 0.25 Nb 0.25 Ta 0.25 W 0.25 Transition metal element powders (all with purities > 99%) were weighed at nominal ratios, mixed, and ball-milled for 5 hours. The tungsten carbide ball mill jar was sealed with tape in an Ar environment to prevent powder oxidation. The ball-milled powder was then pressed into particles with a diameter of 10 mm. The sample was placed on the surface of the lower electrode 706b, and plasma was generated within the gap 708 using a programmable power supply. The generated plasma heated the particles to a plasma temperature of approximately 4700 K (measured by Rayleigh scattering) for 10 seconds, after which the sintered particles were cooled to room temperature.

[0177] The disclosed plasma device can also be used to generate high-value carbon materials (e.g., carbon nanotubes (CNTs)) simply by heating biomass carbon or carbon black without any catalyst. Specifically, 50 mg of carbon black powder is dispersed on the surface of the lower-tipped reinforcing electrode 706b, and plasma is generated within a gap 708 using a programmable power supply. The generated plasma heats the powder for 10 seconds at a plasma temperature of approximately 6600 K (with an input current of 40 A, as measured by Rayleigh scattering), after which the material is cooled to room temperature for further characterization. Figure 9CAs shown, imaging after plasma treatment revealed that the vast majority of the carbon black was converted into multi-walled CNTs consisting of approximately 5–15 carbon layers. Transmission electron microscopy (TEM) was also used to analyze the ends of the CNTs, and no metal nanoparticle catalysts were observed. These results indicate that the conversion of carbon black to CNTs is due to the high-temperature plasma treatment alone, rather than to potential metal contaminants in the feedstock. Electron energy loss spectroscopy (EELS) analysis of the prepared CNTs also showed typical characteristic carbon K-edge profiles, consistent with CNT profiles described in the literature. These results demonstrate the potential of the disclosed plasma device for producing value-added products, such as CNTs, from carbon black (a widely available and inexpensive petroleum industry byproduct).

[0178] By constructing a platform equipped with a focused plasma beam (similar to...) Figures 5B-5C The apparatus shown discloses a plasma process suitable for three-dimensional manufacturing devices, particularly powder bed melting / sintering systems. Specifically, a small cathode carbon felt electrode (8 mm in diameter) is used to generate the plasma, and the input current is carefully adjusted to focus the plasma beam into a filament with a column radius of approximately 1 mm. The carbon felt strip serves as the anode electrode and facilitates electron transfer. The carbon felt strip also supports the sample (pre-pressed particles made of multi-element metal powder). The carbon felt strip is connected to a motor and can move along a pre-set path. For the sample, tungsten powder (99.9%) is pressed into particles and placed on the carbon felt strip. After plasma activation, the carbon felt strip with the particles on it moves relative to the focused plasma. After scanning, the heated sample is gradually cooled to room temperature for further analysis. Figure 10A Cross-sectional SEM images of tungsten samples obtained by this powder bed melting / sintering process are shown, in which a very dense structure can be obtained compared with the unprocessed particles, demonstrating the excellent melting / sintering capability of this technology.

[0179] In addition to bulk samples, the disclosed plasma apparatus can also be used for coating deposition. As proof of concept, a platform equipped with a focused plasma beam (similar to...) Figures 5B-5C The apparatus shown is used to form an ultra-high temperature ceramic (UHTC) coating on top of metal alloys, for example, to improve their high-temperature resistance. Specifically, it uses (Mo...) 0.2 Ta 0.2 Ti 0.2 W 0.2 Zr 0.2Boron (>98%), molybdenum (99.9%), tantalum (99.98%), titanium (99.99%), tungsten (99.95%), and zirconium (99.5%) powders were weighed in the B2 ratio, mixed, and then ball-milled for 3 hours. An excess of 80 mol% boron powder was added to compensate for the evaporation loss of boron oxide during HEB formation. The powder was further heated to 1800°C in an argon-filled glove box by a carbon heater to initiate a self-propagating reaction. Toluene (45 wt.%), fish oil (0.5 wt.%), and powder (40 wt.%) were mixed and ground for 3 hours, followed by the addition of polyvinyl butyral (6 wt.%) and butyl benzyl phthalate (8.5 wt.%), and then ground for another 6 hours to form a slurry. The slurry was cast onto the surface of an Nb-10Hf-1Ti alloy substrate to form a coating, followed by calcination at 450°C for 1 hour.

[0180] A 25.4 mm diameter carbon felt cathode electrode is used to generate plasma, and a carbon felt strip is used as the anode electrode. The carbon felt strip supports the coated sample and facilitates electron transfer. Upon plasma activation, the carbon felt strip moves relative to the plasma over the HEB-coated alloy sample, ensuring uniform heating of the sample. After scanning, the sample is gradually cooled to room temperature for further analysis. Figure 10B As shown, the plasma-treated sample exhibits a high-entropy diboride (HEB) coating on the surface of the C103 alloy (Nb-10Hf-1Ti), which confirms that there are no gaps between the coating and the substrate and that it has good adhesion.

[0181] The disclosed plasma process's high heating / cooling rates can be used for the synthesis and processing of certain materials. For example, in high-temperature synthesis processes, high cooling rates can offer several advantages, as the ability to rapidly cool materials after processing at high temperatures can influence their microstructure, mechanical properties, and performance characteristics. Some of the key advantages of high cooling rates include, but are not limited to:

[0182] • Fine microstructure: Rapid cooling can lead to the formation of fine, uniform microstructures in materials. A finer microstructure can improve mechanical properties such as strength, hardness, and wear resistance.

[0183] • Retaining metastable phases and reducing segregation and precipitation: Rapid cooling helps retain the metastable phases formed during high-temperature synthesis. Rapid cooling rates minimize the segregation of alloying elements and the formation of unwanted precipitates, resulting in materials with more uniform properties, superior mechanical properties, and better corrosion resistance.

[0184] • Improved productivity and energy efficiency: High cooling rates reduce overall processing time, thereby increasing productivity and reducing energy consumption. This is especially important for industries with high throughput and energy efficiency requirements, such as electronics manufacturing and large-scale metal processing.

[0185] As described above, the disclosed plasma process can cycle the plasma temperature between 1000K and 6000K in less than 1 second, with an overall heating / cooling rate of approximately 10. 3 K / s (initial cooling rate can reach approximately 10 K / s) 5 This excellent tunability is attributed to the low voltage barrier of the arc plasma transition achieved by the tip-enhanced electrode, and to the rapid power cut-off, features that can be used to synthesize glass-phase ceramic materials that are difficult to achieve by conventional methods, such as spark plasma sintering.

[0186] High heating / cooling rates can also be used for nonequilibrium synthesis, such as the amorphous ceramics described above. To further demonstrate its utility for nonequilibrium synthesis, the disclosed plasma process was used to manufacture high-entropy refractory alloy (RHEA) microparticles with ultra-hard properties and atomized tungsten tetraboride (WB4) microparticles. Medium / high entropy alloys are a relatively new class of materials containing multiple elements in approximately equal proportions. By atomizing medium / high entropy alloys into fine microparticles and controlling their size, composition, and morphology, their properties, such as mechanical strength, ductility, and corrosion resistance, can be tuned. Atomized medium / high entropy refractory alloy powders can be widely used in additive manufacturing, such as powder bed melting or binder spraying, as well as for surface coatings.

[0187] To produce RHEA microparticles, elemental powders (such as Mo, Nb, Ta, and W) are supplied by gravity (e.g., using a method similar to...). Figure 4G The device is supplied with plasma. The powder is heated and melted in the plasma region to form a high-entropy liquid, then rapidly cooled to form atomized particles, which are subsequently collected. The size of the atomized powder can be controlled by adjusting the temperature and powder flow rate. The atomization, spheroidization, and alloying of the RHEA synthesis process benefit not only from the extremely high temperatures (up to 8000 K) provided by the plasma generated by the tip-enhanced carbon electrodes, but also from the long residence time in the reaction zone provided by the uniform and stable plasma distribution within the gaps between the carbon electrodes.

[0188] The resulting atomized MoNbTaW refractory powder was a fine, silvery-gray particle, contrasting with the black powder mixture of the single component. Images of the atomized MoNbTaW refractory powder showed a high degree of sphericity, with no satellite particles observed adhering to the surface of the larger particles. The statistically measured average particle size was 81.2 ± 13.4 μm. EDS spectra of the MoNbTaW powder sample showed that the four elements were uniformly distributed within the particles. Figure 11XRD patterns of RHEA powder and its precursor powder, obtained by plasma atomization, are shown. The clear peak shifts in the MoNbTaWRHEA powder and the disappearance of the diffraction peaks of the individual components indicate alloying among the four components. The versatility of this method for synthesizing plasma-atomized RHEA powder is further validated by expanding the range of refractory metal powders involved, particularly to WNbTi and MoNbTaWCr, which yield similar results.

[0189] The alloying process, crystal structure, and chemical composition of refractory metal powders can be adjusted by applying a temperature that depends on the voltage, current, gap distance, and / or gas pressure between electrodes. The size of the atomized alloy powder can be adjusted through atomizer design. The argon carrier gas can be optimized for introducing the mixed refractory metal powder precursor into the plasma region (e.g., powder feed rate, feed volume, etc.) to further improve production efficiency.

[0190] Furthermore, the disclosed plasma process is used to synthesize atomized WB4 microparticles. The synthesis route is similar to that of the medium / high entropy alloy powders described above, but tungsten and boron powders are pre-mixed and passed through a plasma region. The ultra-high temperature of the plasma drives the reaction, forming WB4 phase microparticles during cooling. Cross-sectional SEM images of the resulting WB4 microparticles show a structure and morphology similar to bulk WB4 in the literature, but here atomized powder is synthesized instead of bulk material. This atomized WB4 powder can be used for additive manufacturing.

[0191] Other examples of the disclosed technology

[0192] In view of the above-described embodiments of the disclosed subject matter, this application discloses additional examples of the clauses listed below. It should be noted that a feature of a single clause, or a combination of more than one feature of the clause, and optionally, a combination with one or more features of one or more other clauses, are also further examples falling within the scope of this application.

[0193] Clause 1. A method comprising:

[0194] A volumetric plasma is generated between a first electrode and a second electrode, which are separated from each other by a gap. The first electrode includes a first substrate layer and a plurality of first protrusions extending from the first substrate layer toward the second electrode along a first direction.

[0195] The first substrate layer includes a first conductive material.

[0196] At least a portion of the first protruding portion includes a second conductive material.

[0197] The melting temperature of the first conductive material and the melting temperature of the second conductive material are at least 1000K, and

[0198] During generation, the temperature of the volumetric plasma between the first and second electrodes is in the range of 1000-8000K, including 1000K and 8000K.

[0199] Clause 2. The method according to any clause or example herein, particularly the method of Clause 1, wherein:

[0200] The cross-sectional dimension of each first protrusion in a plane substantially perpendicular to the first direction is less than or equal to 1 mm, for example, less than or equal to 500 μm;

[0201] The length of each first protrusion along the first direction is less than or equal to 1 cm, for example, less than or equal to 5 mm;

[0202] The interval between each first protrusion and an adjacent first protrusion in a plurality of first protrusions is less than or equal to 1 mm; or

[0203] Any combination of the above items.

[0204] Clause 3. The method according to any clause or example herein, particularly any of clauses 1-2, wherein:

[0205] The cross-sectional dimensions of each first protrusion are in the range of 1-100 μm, including 1 μm and 100 μm, for example, in the range of 1-50 μm, including 1 μm and 50 μm;

[0206] The length of each first protrusion is in the range of 200-500 μm, including 200 μm and 500 μm;

[0207] The spacing between adjacent first protrusions is less than or equal to 100 μm, for example, less than or equal to 50 μm;

[0208] The density of the first protruding part is at least 10. 4 pcs / cm 2 ;or

[0209] Any combination of the above items.

[0210] Clause 4. The method according to any clause or example herein, particularly the method of any one of clauses 1-3, wherein the spacing between adjacent first protrusions is in the range of 3-20 μm, including 3 μm and 20 μm.

[0211] Clause 5. The method according to any clause or example herein, particularly any of clauses 1-4, wherein the thickness of the gap along the first direction is in the range of 1 mm to 10 cm, including 1 mm and 10 cm, for example, in the range of 1 mm to 1 cm, including 1 mm and 1 cm.

[0212] Clause 6. The method according to any clause or example herein, particularly any one of clauses 1-5, wherein generating volumetric plasma comprises applying a direct current (DC) voltage between a first electrode and a second electrode.

[0213] Clause 7. The method according to any clause or example herein, particularly any one of clauses 1-5, wherein generating volumetric plasma comprises applying an alternating current (AC) voltage between a first electrode and a second electrode.

[0214] Clause 8. The method according to any clause or example herein, particularly any one of clauses 1-5, wherein generating volumetric plasma comprises applying a pulsed voltage waveform between the first electrode and the second electrode.

[0215] Clause 9. The method according to any clause or example herein, particularly any of clauses 1-8, wherein during the generation of volume plasma, the peak voltage applied between the first electrode and the second electrode is less than or equal to 100V, and / or during the generation of volume plasma, the peak current between the first electrode and the second electrode is less than or equal to 100A.

[0216] Clause 10. The method according to any clause or example herein, particularly any one of clauses 1-9, wherein the generation steps include:

[0217] Volumetric plasma is initiated by applying a first direct current (DC) voltage, a first alternating current (AC) voltage, or a first pulse voltage waveform between the first and second electrodes; and

[0218] The initiated volumetric plasma is maintained by applying a second DC voltage, a second AC voltage, or a second pulse voltage waveform between the first and second electrodes.

[0219] The absolute value of the peak voltage of the second DC voltage, the second AC voltage, or the second pulse voltage waveform is less than the absolute value of the peak voltage of the first DC voltage, the first AC voltage, or the first pulse voltage waveform.

[0220] Clause 11. The method according to any clause or example herein, particularly the method of Clause 10, wherein the absolute value of the peak voltage of the first DC voltage, the first AC voltage, or the first pulse waveform is in the range of 10-100V, including 10V and 100V, and / or the absolute value of the peak voltage of the second DC voltage, the second AC voltage, or the second pulse waveform is in the range of 10-50V, including 10V and 50V.

[0221] Clause 12. The method according to any clause or example herein, particularly any one of clauses 10-11, wherein during the initiation of the volume plasma, a first DC voltage, a first AC voltage, or a first pulse voltage waveform is applied between the first electrode and the second electrode for at least 1 minute, and / or during the maintenance of the initiation of the volume plasma, a second DC voltage, a second AC voltage, or a second pulse voltage waveform is applied between the first electrode and the second electrode for at least 1 minute.

[0222] Clause 13. The method according to any clause or example herein, particularly any of clauses 1-12, wherein the generation of a volumetric plasma between the first and second electrodes is carried out at approximately atmospheric pressure.

[0223] Clause 14. The method according to any clause or example herein, particularly any of clauses 1-13, wherein the generated plasma has a dimension of at least 1 mm along a second direction, for example in the range of 1 mm to 100 cm, including 1 mm and 100 cm, and the second direction lies in a plane substantially perpendicular to the first direction.

[0224] Clause 15. The method according to any clause or example herein, particularly any of clauses 1-14, wherein plasma is generated at a pressure range of 1 Torr to 10 atm (inclusive) with or without the application of an external magnetic field.

[0225] Clause 16. The method according to any clause or example herein, particularly any of clauses 1-15, wherein the first conductive material and the second conductive material are the same material.

[0226] Clause 17. The method according to any clause or example herein, particularly any of clauses 1-16, wherein the first conductive material, the second conductive material, or both are formed of carbon or graphite.

[0227] Clause 18. The method according to any clause or example herein, particularly any of clauses 1-17, wherein the first conductive material, the second conductive material, or both are formed of a refractory metal, a refractory metal alloy, or both.

[0228] Clause 19. The method according to any clause or example herein, particularly any of clauses 1-18, wherein the first conductive material, the second conductive material, or both are formed of a metal carbide, silicon carbide, a metal nitride, a metal diboride, or any combination thereof.

[0229] Clause 20. The method according to any clause or embodiment herein, particularly the method of any one of clauses 1-19, wherein:

[0230] The second electrode includes a second base layer and a plurality of second protrusions, the plurality of second protrusions extending from the second base layer toward the first electrode along a first direction;

[0231] The second substrate layer includes a third conductive material;

[0232] At least a portion of the second protrusion includes a fourth conductive material; and

[0233] The melting temperatures of the third and fourth conductive materials are at least 1000K.

[0234] Clause 21. The method according to any clause or example herein, particularly any of clauses 1-20, wherein the first conductive material and the second conductive material are the same material, the third conductive material and the fourth conductive material are the same material, the second conductive material and the fourth conductive material are the same material, the first conductive material and the third conductive material are the same material, or any combination thereof.

[0235] Clause 22. The method according to any clause or embodiment herein, particularly the method of any one of clauses 1-21, wherein:

[0236] Prior to the generation step, at least a portion of the first protrusion, each end of the first protrusion, has a first shape, and after the generation step, at least a portion of the first protrusion, each end of the first protrusion, has been sharpened to have a first tapered shape different from the first shape; and / or

[0237] Before the generation step, at least a portion of the second protrusion has a second shape at the end of each second protrusion, and after the generation step, at least a portion of the second protrusion has a second cone shape at the end of each second protrusion that is different from the second shape.

[0238] Clause 23. The method according to any clause or embodiment herein, particularly the method of any one of clauses 1-22, wherein:

[0239] The first electrode also includes a plurality of third protrusions that extend further along a first direction from the first substrate layer toward the second electrode than the plurality of first protrusions, and at least a portion of the third protrusions are formed of a fifth conductive material.

[0240] The second electrode also includes a plurality of fourth protrusions that extend further from the second substrate layer toward the first electrode along a first direction than the plurality of second protrusions, and at least a portion of the fourth protrusions are formed of a sixth conductive material.

[0241] At least one third protrusion contacts at least one fourth protrusion within the gap, or the distance between the third and fourth protrusions does not exceed 25 μm, for example, less than or equal to 5 μm; and

[0242] The melting temperature of the fifth conductive material and the melting temperature of the sixth conductive material are at least 1000K.

[0243] Clause 24. The method according to any clause or example herein, particularly the method of Clause 23, wherein the generation step comprises: initiating a volumetric plasma by a gas discharge between a third protrusion and a fourth protrusion, and maintaining the volumetric plasma by a gas discharge between a first protrusion and a second protrusion.

[0244] Clause 25. The method according to any clause or example herein, particularly any of clauses 23-24, further comprises, prior to initiating the volumetric plasma, applying a first voltage between the first electrode and the second electrode such that current flows through a contact portion of at least one of the third and fourth protrusions and causes Joule heating of the contact portion, the Joule heating causing breakage of at least one of the third and / or fourth protrusions such that a spacing of 1-25 μm, including 1 μm and 25 μm, for example, 1-5 μm, including 1 μm and 5 μm, is formed between at least one of the third protrusions and at least one of the fourth protrusions.

[0245] Clause 26. The method according to any clause or example herein, particularly any one of clauses 23-25, further comprises, prior to initiating the volumetric plasma, applying a first voltage between the first electrode and the second electrode such that current flows through a contact portion of at least one of the third and fourth protrusions and causes Joule heating of the contact portion, the Joule heating causing breakage of at least one of the third and / or fourth protrusions such that a distance not greater than three times the cross-sectional dimension of the third or fourth protrusion is formed between at least one of the third protrusions and at least one of the fourth protrusions.

[0246] Clause 27. The method according to any clause or example herein, particularly any of clauses 23-26, wherein the first conductive material and the second conductive material are the same material, the third conductive material and the fourth conductive material are the same material, the fifth conductive material and the sixth conductive material are the same material, the second conductive material and the fourth conductive material are the same material, the first conductive material and the third conductive material are the same material, the second conductive material and the fifth conductive material are the same material, the fourth conductive material and the sixth conductive material are the same material, or any combination thereof.

[0247] Clause 28. The method according to any clause or example herein, particularly any of clauses 23-27, wherein one, part or all of the first to sixth conductive materials consists of or includes the following: (i) carbon or graphite, (ii) refractory metal, refractory metal alloy or both, (iii) metal carbide, silicon carbide, metal nitride, metal diboride or any combination thereof, or (iv) any combination of items (i) to (iii).

[0248] Clause 29. The method according to any clause or embodiment of this document, particularly the method of any one of clauses 23-28, wherein:

[0249] The cross-sectional dimension of each third protrusion and / or each fourth protrusion in a plane substantially perpendicular to the first direction is less than or equal to 1 mm, for example, less than or equal to 500 μm;

[0250] The cross-sectional dimensions of each third protrusion and / or each fourth protrusion are in the range of 1-100 μm, including 1 μm and 100 μm, for example, in the range of 1-50 μm, including 1 μm and 50 μm;

[0251] The length of each third protrusion and / or each fourth protrusion along the first direction is greater than 1 mm, for example, in the range of 10-100 mm, including 10 mm and 100 mm; or

[0252] Any combination of the above items.

[0253] Clause 30. The method according to any clause or example herein, particularly any of clauses 1-29, further includes the following steps prior to the generation step:

[0254] The first electrode is formed by cutting a portion from a first fabric comprising woven carbon fibers or metal fibers, the first substrate being the remaining portion of the first fabric after cutting, and a plurality of first protrusions and / or a plurality of third protrusions being carbon fibers or metal fibers exposed from the cut surface of the remaining portion of the first fabric; and / or

[0255] The second electrode is formed by cutting a portion of a second fabric, including woven carbon fiber or metal fiber, the second base layer being the remaining portion of the second fabric after cutting, and a plurality of second protrusions and / or a plurality of fourth protrusions being carbon fiber or metal fiber exposed from the cut surface of the remaining portion of the second fabric.

[0256] Clause 31. The method according to any clause or example herein, particularly the method of Clause 30, wherein the remainder of the first fabric and / or the remainder of the second fabric comprises a plurality of woven carbon fibers or metal fibers extending in a second direction in a plane substantially perpendicular to the first direction.

[0257] Clause 32. The method according to any clause or example herein, particularly any of clauses 1-29, further includes the following steps prior to the generation step:

[0258] The first electrode is formed by roughening the surface of a first fabric containing woven carbon fibers or metal fibers. A first substrate layer is the main body of the first fabric. Multiple first protrusions and / or multiple third protrusions are carbon fibers or metal fibers broken at the surface of the main body of the first fabric after roughening, and / or carbon fibers or metal fibers exposed from the surface of the main body of the first fabric; and / or

[0259] The second electrode is formed by roughening the surface of a second fabric containing woven carbon fibers or metal fibers. The second base layer is the main body of the second fabric. The plurality of second protrusions and / or the plurality of fourth protrusions are carbon fibers or metal fibers broken at the surface of the main body of the second fabric after roughening and / or carbon fibers or metal fibers exposed from the surface of the main body of the second fabric.

[0260] Clause 33. The method according to any clause or example herein, particularly the method of Clause 32, wherein the main portion of the first fabric and / or the main portion of the second fabric comprises a plurality of woven carbon fibers or metal fibers extending in a second direction in a plane substantially perpendicular to the first direction.

[0261] Clause 34. The method according to any clause or example herein, particularly any of clauses 1-29, further includes the following steps prior to the generation step:

[0262] Multiple first protrusions are formed on the first base layer;

[0263] Multiple third protrusions are formed on the first basal layer;

[0264] Multiple second protrusions are formed on the second base layer;

[0265] Multiple fourth protrusions are formed on the second basal layer; or

[0266] Any combination of the above items.

[0267] Clause 35. The method according to any clause or example herein, particularly the method of Clause 34, wherein forming a plurality of first protrusions, forming a plurality of second protrusions, forming a plurality of third protrusions and / or forming a plurality of fourth protrusions includes employing 3D printing.

[0268] Clause 36. The method according to any clause or example herein, particularly the method of Clause 35, wherein 3D printing includes laser-based direct energy deposition or laser powder bed melting.

[0269] Clause 37. The method according to any clause or example herein, particularly any of clauses 1-36, wherein the first electrode, the second electrode, or both have a non-planar geometry.

[0270] Clause 38. The method according to any clause or embodiment herein, particularly the method of any one of clauses 1-37, wherein:

[0271] The surface area of ​​the second electrode facing the gap is greater than the surface area of ​​the first electrode facing the gap; and

[0272] The method further includes, during the generation step, moving either the first electrode or the second electrode relative to the other electrode to change the position of the generated volumetric plasma.

[0273] Clause 39. The method according to any clause or example herein, particularly any of clauses 1-38, further includes, prior to or concurrently with the generation step, placing one or more precursors in or near the gap between the first electrode and the second electrode, such that volumetric plasma heats the one or more precursors to form one or more products.

[0274] Clause 40. The method according to any clause or example herein, particularly any of clauses 1-39, further includes, during generation, flowing one or more gases and / or one or more precursors through a volumetric plasma, such that the volumetric plasma heats one or more gases and / or one or more precursors to form one or more products.

[0275] Clause 41. The method according to any clause or example herein, particularly the method of Clause 40, wherein the first electrode and the second electrode are arranged such that the thickness of the gap along the first direction is at a non-zero angle relative to the direction of gravity, such that gravity facilitates the flow of one or more precursors in the gap.

[0276] Clause 42. The method according to any clause or example herein, particularly any of clauses 40-41, wherein the flow comprises supporting one or more precursors within a volumetric plasma using a carrier gas and / or a substrate, flowing into the volumetric plasma, and / or flowing out of the volumetric plasma.

[0277] Clause 43. The method according to any clause or embodiment of this document, particularly the method of clause 42, wherein the carrier gas includes an inert gas.

[0278] Clause 44. The method according to any clause or example herein, particularly any of clauses 39-43, further includes: stopping the generation of volumetric plasma, removing one or more products from the volumetric plasma, and / or removing the volumetric plasma away from one or more products.

[0279] Clause 45. The methods according to any clause or example herein, particularly any of clauses 39-44, further include: actively cooling one or more products, and / or subjecting one or more products to an airflow to break the one or more products into smaller droplets.

[0280] Clause 46. The method according to any clause or example herein, particularly any one of clauses 1-45, wherein the generation steps include:

[0281] Volumetric plasma is initiated by applying a voltage when the gap between the first and second electrodes is at a first distance.

[0282] Moving the first electrode away from the second electrode and / or moving the second electrode away from the first electrode; and

[0283] The activated volumetric plasma is maintained by applying a voltage when the gap between the first and second electrodes is greater than a first distance.

[0284] Clause 47. The method according to any clause or embodiment of this document, particularly the method of any one of clauses 1-46, wherein the generation step causes the volumetric plasma to be maintained in the same volume for at least 10 minutes.

[0285] Clause 48. The method according to any clause or example herein, particularly any of clauses 1-47, wherein the temperature of the volumetric plasma is spatially uniform, for example, wherein the temperature variation of the volumetric plasma in a second direction substantially perpendicular to the first direction does not exceed 10%.

[0286] Clause 49. The method according to any clause or embodiment herein, particularly the method of any one of clauses 1-48, wherein:

[0287] One, part or all of the first protrusion, the second protrusion, the third protrusion and the fourth protrusion have a substantially one-dimensional tip at their end near or within the gap;

[0288] One, part or all of the first protrusion, the second protrusion, the third protrusion and the fourth protrusion have substantially two-dimensional tips at their ends near or within the gap;

[0289] One, part or all of the first, second, third and fourth protruding portions have a blunt tip at their end near or within the gap; or

[0290] Any combination of the above items.

[0291] Clause 50. A system configured to perform the methods of any clause or example herein, particularly any of clauses 1-49, for example, as per [the relevant clause]. Figures 1A-11 The method described in any of the figures.

[0292] Clause 51. A system comprising:

[0293] A first electrode includes a first base layer and a plurality of first protrusions. The first base layer includes a first conductive material, and at least a portion of the first protrusions includes a second conductive material. The melting temperature of the first conductive material and the melting temperature of the second conductive material are at least 1000K.

[0294] The second electrode is separated from the first electrode by a gap, and a plurality of first protrusions extend from the first substrate layer toward the second electrode along a first direction;

[0295] A power source, electrically coupled to the first and second electrodes; and

[0296] A control system operatively coupled to and configured to control the operation of a power source, the control system including one or more processors and a computer-readable storage medium storing instructions which, when executed by one or more processors, cause the power source to apply a voltage between a first electrode and a second electrode, thereby generating a volumetric plasma in or near a gap, the volumetric plasma having a temperature in the range of 1000-8000K, including 1000K and 8000K.

[0297] Clause 52. A system pursuant to any clause or example herein, particularly any of clauses 50-51, wherein:

[0298] Each first protrusion has a cross-sectional dimension of less than or equal to 1 mm in a plane substantially perpendicular to the first direction, for example, less than or equal to 500 μm;

[0299] The length of each first protrusion along the first direction is less than or equal to 1 cm, for example, less than or equal to 5 mm;

[0300] The interval between each first protrusion and an adjacent first protrusion in a plurality of first protrusions is less than or equal to 1 mm; or

[0301] Any combination of the above items.

[0302] Clause 53. A system pursuant to any clause or example herein, particularly any of clauses 50-52, wherein:

[0303] The cross-sectional dimensions of each first protrusion are in the range of 1-100 μm, including 1 μm and 100 μm, for example, in the range of 1-50 μm, including 1 μm and 50 μm;

[0304] The length of each first protrusion is in the range of 200-500 μm, including 200 μm and 500 μm;

[0305] The spacing between adjacent first protrusions is less than or equal to 100 μm, for example, less than or equal to 50 μm;

[0306] The density of the first protruding part is at least 10. 4 pcs / cm 2 ;or

[0307] Any combination of the above items.

[0308] Clause 54. A system according to any clause or example herein, particularly a system of any of clauses 50-53, wherein the spacing between adjacent first protrusions is in the range of 3-20 μm, including 3 μm and 20 μm.

[0309] Clause 55. A system according to any clause or example herein, particularly a system of any of clauses 50-54, wherein the thickness of the gap along the first direction is in the range of 1 mm to 10 cm, including 1 mm and 10 cm, for example in the range of 1 mm to 1 cm, including 1 mm and 10 cm.

[0310] Clause 56. A system according to any clause or example herein, particularly any of clauses 50-55, wherein the power supply is configured to apply a direct current (DC) voltage, an alternating current (AC) voltage, or a pulsed voltage waveform between the first electrode and the second electrode.

[0311] Clause 57. A system according to any clause or example herein, particularly any of clauses 50-56, wherein a computer-readable storage medium stores additional instructions that, when executed by one or more processors, cause a power supply to apply a peak voltage of less than or equal to 100V between a first electrode and a second electrode to generate a volume plasma, and / or to apply a peak current of less than or equal to 100A between the first electrode and the second electrode to generate a volume plasma.

[0312] Clause 58. A system pursuant to any clause or example herein, and particularly any of clauses 50-57, wherein a computer-readable storage medium stores additional instructions that, when executed by one or more processors, also cause the power supply to perform the following:

[0313] Volumetric plasma is initiated by applying a first direct current (DC) voltage, a first alternating current (AC) voltage, or a first pulse voltage waveform between the first and second electrodes; and

[0314] The initiated volumetric plasma is maintained by applying a second DC voltage, a second AC voltage, or a second pulse voltage waveform between the first and second electrodes.

[0315] The absolute value of the peak voltage of the second DC voltage, the second AC voltage, or the second pulse voltage waveform is less than the absolute value of the peak voltage of the first DC voltage, the first AC voltage, or the first pulse voltage waveform.

[0316] Clause 59. A system pursuant to any clause or example herein, particularly the system of Clause 57, wherein the absolute value of the peak voltage of the first DC voltage, the first AC voltage, or the first pulse waveform is in the range of 10-100V, including 10V and 100V, and / or the absolute value of the peak voltage of the second DC voltage, the second AC voltage, or the second pulse waveform is in the range of 10-50V, including 10V and 50V.

[0317] Clause 60. A system according to any clause or example herein, particularly any of clauses 50-59, wherein the dimensions of the first and second electrodes are such that the size of the plasma generated along the second direction is at least 1 mm, for example in the range of 1 mm to 100 cm, including 1 mm and 100 cm, and the second direction lies in a plane substantially perpendicular to the first direction.

[0318] Clause 61. A system according to any clause or example herein, particularly any of clauses 50-60, wherein the system is configured to generate volumetric plasma at pressures in the range of 1 Torr to 10 atm (inclusive of 1 Torr and 10 atm, e.g., about 1 atm).

[0319] Clause 62. A system according to any clause or example herein, particularly any of clauses 50-61, wherein the first conductive material is the same as the second conductive material.

[0320] Clause 63. A system pursuant to any clause or example herein, particularly any of clauses 50-62, wherein the first conductive material, the second conductive material, or both comprise a refractory metal, a refractory metal alloy, or both.

[0321] Clause 64. A system according to any clause or example herein, particularly a system of any of clauses 50-63, wherein the first conductive material, the second conductive material, or both comprise a metal carbide, silicon carbide, a metal nitride, a metal diboride, or any combination thereof.

[0322] Clause 65. A system pursuant to any clause or example herein, particularly any of clauses 50-64, wherein:

[0323] The second electrode includes a second base layer and a plurality of second protrusions, the plurality of second protrusions extending from the second base layer toward the first electrode along a first direction;

[0324] The second substrate layer includes a third conductive material;

[0325] At least a portion of the second protrusion includes a fourth conductive material; and

[0326] The melting temperatures of the third and fourth conductive materials are at least 1000K.

[0327] Clause 66. A system according to any clause or example herein, particularly a system of any one of clauses 50-65, wherein at least one of the first to fourth conductive materials is identical to another of the first to fourth conductive materials.

[0328] Clause 67. A system according to any clause or example herein, particularly a system of any one of clauses 50-66, wherein: at least a portion of the first protrusion has a tapered end at the end of each first protrusion, and / or at least a portion of the second protrusion has a tapered end at the end of each second protrusion.

[0329] Clause 68. A system pursuant to any clause or example herein, and in particular any of clauses 50-67, wherein:

[0330] The first electrode also includes a plurality of third protrusions that extend further along a first direction from the first substrate layer toward the second electrode than the plurality of first protrusions, and at least a portion of the third protrusions are formed of a fifth conductive material.

[0331] The second electrode includes a plurality of fourth protrusions extending from the second substrate layer toward the first electrode along a first direction, at least a portion of the fourth protrusions being formed of a sixth conductive material.

[0332] At least one third protrusion contacts at least one fourth protrusion within the gap, or the distance between the third and fourth protrusions does not exceed 25 μm, for example, less than or equal to 5 μm; and

[0333] The melting temperature of the fifth conductive material and the melting temperature of the sixth conductive material are at least 1000K.

[0334] Clause 69. A system pursuant to any clause or example herein, particularly a system pursuant to Clause 68, wherein a computer-readable storage medium stores additional instructions that, when executed by one or more processors, also cause a power source to perform: initiate a volumetric plasma by a gas discharge between a third protrusion and a fourth protrusion, and maintain the initiated volumetric plasma by a gas discharge between a first protrusion and a second protrusion.

[0335] Clause 70. A system according to any clause or example herein, particularly a system of any one of clauses 68-69, wherein a computer-readable storage medium stores additional instructions that, when executed by one or more processors, further cause a power supply to apply a first voltage between a first electrode and a second electrode prior to initiating a volumetric plasma, such that current flows through a contact portion of at least one of a third protrusion and a fourth protrusion and causes Joule heating of the contact portion, the Joule heating causing breakage of at least one of the third and / or fourth protrusions, such that a gap of less than or equal to 10 μm, for example 1-5 μm, including 1 μm and 5 μm, is formed between at least one of the third protrusions and at least one of the fourth protrusions.

[0336] Clause 71. A system according to any clause or example herein, particularly a system of any one of clauses 68-70, wherein at least one of the first to sixth conductive materials is identical to another of the first to sixth conductive materials.

[0337] Clause 72. A system according to any clause or example herein, particularly a system of any one of clauses 50-71, wherein one, part or all of the first to sixth conductive materials comprises: (i) carbon or graphite, (ii) a refractory metal, a refractory metal alloy or both, (iii) a metal carbide, silicon carbide, a metal nitride, a metal diboride or any combination thereof, or (iv) any combination of items (i) to (iii).

[0338] Clause 73. A system pursuant to any clause or example herein, particularly any of clauses 50-72, wherein:

[0339] The maximum cross-sectional dimension of each third protrusion and / or each fourth protrusion in a plane substantially perpendicular to the first direction is less than or equal to 1 mm, for example, less than or equal to 500 μm;

[0340] The maximum cross-sectional dimension of each third protrusion and / or each fourth protrusion is in the range of 1-100 μm, including 1 μm and 100 μm, for example, in the range of 1-50 μm, including 1 μm and 50 μm;

[0341] The length of each third protrusion and / or each fourth protrusion along the first direction is greater than 1 mm, for example, in the range of 10-100 mm, including 10 mm and 100 mm; or

[0342] Any combination of the above items.

[0343] Clause 74. A system according to any clause or example herein, particularly any of clauses 50-73, wherein the first electrode, the second electrode, or both comprise woven carbon fiber or metal fiber.

[0344] Clause 75. A system according to any clause or example herein, particularly a system of any of clauses 50-74, wherein a plurality of first protrusions, a plurality of second protrusions, a plurality of third protrusions and / or a plurality of fourth protrusions comprise 3D printed columns.

[0345] Clause 76. A system according to any clause or example herein, particularly any of clauses 50-75, wherein the first electrode, the second electrode, or both have a non-planar geometry.

[0346] Clause 77. A system according to any clause or example herein, particularly any of clauses 50-76, further includes: a first translation stage configured to move a first electrode and / or a second translation stage configured to move a second electrode.

[0347] Clause 78. A system according to any clause or example herein, particularly the system of Clause 77, wherein a control system is operatively coupled to a first translation stage and / or a second translation stage and configured to control the operation of the first translation stage and / or the second translation stage, and a computer-readable storage medium stores additional instructions that, when executed by one or more processors, cause the first translation stage and / or the second translation stage to move one of the first and second electrodes relative to the other electrode.

[0348] Clause 79. A system according to any clause or example herein, particularly any of clauses 77-78, wherein the surface area of ​​the second electrode facing the gap is greater than the surface area of ​​the first electrode facing the gap, and a computer-readable storage medium stores instructions that, when executed by one or more processors, cause a first translation stage and / or a second translation stage to move one of the first and second electrodes relative to the other electrode to change the position of the volumetric plasma.

[0349] Clause 80. A system pursuant to any clause or example herein, particularly any of clauses 77-79, wherein a computer-readable storage medium stores instructions that, when executed by one or more processors, cause the following to be performed:

[0350] The first translation stage and / or the second translation stage position the first electrode and the second electrode such that the gap is at a first distance;

[0351] The power source initiates the volumetric plasma by applying voltage when the gap between the first and second electrodes is at a first distance.

[0352] After initiating the volumetric plasma, the first translation stage and / or the second translation stage are used to move the first and second electrodes away from each other; and

[0353] The power source sustains the initiated volumetric plasma by applying voltage when the gap between the first and second electrodes is greater than a first distance.

[0354] Clause 81. A system according to any clause or example herein, particularly any of clauses 50-80, wherein the first electrode and the second electrode are arranged such that the thickness of the gap along the first direction is at a non-zero angle relative to the direction of gravity.

[0355] Clause 82. A system pursuant to any clause or example herein, particularly any of clauses 50-81, wherein:

[0356] One, part or all of the first protrusion, the second protrusion, the third protrusion and the fourth protrusion have a substantially one-dimensional tip at their end near or within the gap;

[0357] One, part or all of the first protrusion, the second protrusion, the third protrusion and the fourth protrusion have substantially two-dimensional tips at their ends near or within the gap;

[0358] One, part or all of the first, second, third and fourth protruding portions have a blunt tip at their end near or within the gap; or

[0359] Any combination of the above items.

[0360] Clause 83. A method for operating a system of any clause or example herein, particularly a method of any of clauses 1-49, for example, as per [the relevant clause]. Figures 1A-11 The method described by any of the graphs in the diagram.

[0361] Clause 84. Methods for generating and / or using plasma based on any example or combination thereof disclosed herein, for example, as per [reference to...] Figures 1A-11 The method described by any of the graphs in the diagram.

[0362] in conclusion

[0363] Any features shown or described in this document, such as Figures 1A-11 And any feature shown or described in Clauses 1-84 may be used in combination with any other feature shown or described herein, such as Figures 1A-11 And any features shown or described in Clauses 1-84, to provide a system, apparatus, structure, method, and embodiment not otherwise shown or specifically described herein. All features described herein are independent of each other and may be used in combination with any other features described herein, except where structurally impossible. Given that the principles of the disclosed technology can be applied to many possible embodiments, it should be recognized that the embodiments shown are merely examples and should not be considered as limiting the scope of the disclosed technology. Rather, that scope is defined by the following claims. Therefore, we claim all that is within the scope and spirit of these claims.

Claims

1. A method comprising: A volumetric plasma is generated between a first electrode and a second electrode, which are separated from each other by a gap. The first electrode includes a first substrate layer and a plurality of first protrusions extending from the first substrate layer toward the second electrode along a first direction. The first substrate layer includes a first conductive material. At least a portion of the first protruding portion includes a second conductive material. The melting temperatures of both the first and second conductive materials are at least 1000K, and During generation, the temperature of the volumetric plasma between the first and second electrodes is in the range of 1000-8000K, including 1000K and 8000K.

2. The method according to claim 1, wherein: The maximum cross-sectional dimension of each first protrusion in a plane substantially perpendicular to the first direction is less than or equal to 500 μm; The length of each first protrusion along the first direction is less than or equal to 1 cm; The interval between each first protrusion and an adjacent first protrusion in a plurality of first protrusions is less than or equal to 1 mm; or Any combination of the above items.

3. The method according to claim 2, wherein: The maximum cross-sectional dimension of each first protrusion is in the range of 1-100 μm, including 1 μm and 100 μm; The length of each first protrusion is in the range of 200-500 μm, including 200 μm and 500 μm; The spacing between adjacent first protrusions is less than or equal to 100 μm; The density of the first protruding part is at least 10. 4 pcs / cm 2 ;or Any combination of the above items.

4. The method according to claim 3, wherein, The spacing between adjacent first protrusions is in the range of 1-50 μm, including 1 μm and 50 μm.

5. The method according to claim 1, wherein, The thickness of the gap along the first direction is in the range of 1 mm to 1 cm, including 1 mm and 1 cm.

6. The method according to claim 1, wherein, Generating volumetric plasma involves applying a direct current (DC) voltage between the first and second electrodes.

7. The method according to claim 1, wherein, Generating volumetric plasma involves applying an alternating current (AC) voltage between the first and second electrodes.

8. The method according to claim 1, wherein, Generating volumetric plasma involves applying a pulsed voltage waveform between the first and second electrodes.

9. The method according to any one of claims 6-8, wherein: During the generation of volumetric plasma, the peak voltage applied between the first electrode and the second electrode is less than or equal to 100V; During the generation of volumetric plasma, the peak current between the first and second electrodes is less than or equal to 100 A; or Both of the above.

10. The method according to claim 1, wherein, The generation includes the following items: Volumetric plasma is initiated by applying a first direct current (DC) voltage, a first alternating current (AC) voltage, or a first pulse voltage waveform between the first electrode and the second electrode. as well as The initiated volumetric plasma is maintained by applying a second DC voltage, a second AC voltage, or a second pulse voltage waveform between the first and second electrodes. The absolute value of the peak voltage of the second DC voltage, the second AC voltage, or the second pulse voltage waveform is less than the absolute value of the peak voltage of the first DC voltage, the first AC voltage, or the first pulse voltage waveform.

11. The method of claim 10, wherein: The absolute value of the peak voltage of the first DC voltage, the first AC voltage, or the first pulse waveform is in the range of 10-100V, including 10V and 100V. The absolute value of the peak voltage of the second DC voltage, the second AC voltage, or the second pulse waveform is in the range of 10-50V, inclusive; or Both of the above.

12. The method according to claim 10, wherein: During the initiation of the volumetric plasma, a first DC voltage, a first AC voltage, or a first pulse voltage waveform is applied between the first electrode and the second electrode for at least 1 minute; During the period of maintaining the initiated volumetric plasma, a second DC voltage, a second AC voltage, or a second pulse voltage waveform is applied between the first and second electrodes for at least 1 minute; or Both of the above.

13. The method according to claim 1, wherein, The generation of volumetric plasma between the first and second electrodes occurs under atmospheric pressure.

14. The method according to claim 1, wherein, The generated plasma has a size in the range of 1 mm to 100 cm along the second direction, including 1 mm and 100 cm, and the second direction lies in a plane substantially perpendicular to the first direction.

15. The method according to claim 1, wherein, Plasma is generated at pressures ranging from 1 Torr to 10 atm, with or without the application of an external magnetic field.

16. The method according to claim 1, wherein, The first conductive material and the second conductive material are the same material.

17. The method according to claim 1, wherein, The first conductive material, the second conductive material, or both include carbon or graphite.

18. The method according to claim 1, wherein, The first conductive material, the second conductive material, or both include refractory metals, refractory metal alloys, or both of the foregoing.

19. The method according to claim 1, wherein, The first conductive material, the second conductive material, or both include metal carbides, silicon carbide, metal nitrides, metal diborides, or any combination thereof.

20. The method according to claim 1, wherein: The second electrode includes a second base layer and a plurality of second protrusions extending from the second base layer toward the first electrode along a first direction; The second substrate layer includes a third conductive material; At least a portion of the second protrusion includes a fourth conductive material; as well as The melting temperature of the third conductive material and the melting temperature of the fourth conductive material are at least 1000K.

21. The method of claim 20, wherein: The first conductive material and the second conductive material are the same material; The third and fourth conductive materials are the same material; The second and fourth conductive materials are the same material; The first conductive material and the third conductive material are the same material; or Any combination of the above items.

22. The method of claim 20, wherein: Prior to the generation, at least a portion of the first protrusion of the first protrusion has a first shape at its end, and after the generation, at least a portion of the first protrusion of the first protrusion has been sharpened to have a first cone shape different from the first shape. Prior to the generation, at least a portion of the second protrusion, each end of the second protrusion, has a second shape, and after the generation, at least a portion of the second protrusion, each end of the second protrusion, has a second cone shape different from the second shape; or Both of the above.

23. The method of claim 20, wherein: The first electrode further includes a plurality of third protrusions that extend further from the first substrate layer toward the second electrode along a first direction than the plurality of first protrusions, and at least a portion of the third protrusions are formed of a fifth conductive material; The second electrode also includes a plurality of fourth protrusions that extend further from the second substrate layer toward the first electrode along a first direction than the plurality of second protrusions, and at least a portion of the fourth protrusions are formed of a sixth conductive material; At least one third protrusion contacts at least one fourth protrusion in the gap, or the distance between the third protrusion and the fourth protrusion does not exceed 5 μm; as well as The melting temperature of the fifth conductive material and the melting temperature of the sixth conductive material are at least 1000K.

24. The method according to claim 23, wherein, The generation includes: Volumetric plasma is initiated by gas discharge between the third and fourth protrusions; as well as Volumetric plasma is maintained by gas discharge between the first and second protrusions.

25. The method of claim 24, further comprising, prior to initiating the volumetric plasma, applying a first voltage between the first electrode and the second electrode such that current flows through a contact portion of at least one of the third and fourth protrusions and causes Joule heating of the contact portion, the Joule heating causing breakage of at least one of the third and / or fourth protrusions, such that a 1-5 μm gap is formed between at least one of the third protrusions and at least one of the fourth protrusions, the gap including 1 μm and 5 μm.

26. The method according to claim 23, wherein: The first conductive material and the second conductive material are the same material; The third and fourth conductive materials are the same material; The fifth and sixth conductive materials are the same material; The second and fourth conductive materials are the same material; The first conductive material and the third conductive material are the same material; The second conductive material and the fifth conductive material are the same material; The fourth and sixth conductive materials are the same material; or Any combination of the above items.

27. The method according to claim 23, wherein, One, part or all of the first to sixth conductive materials include: (i) Carbon or graphite; (ii) Refractory metals, refractory metal alloys, or both of the above; (iii) Metal carbides, silicon carbide, metal nitrides, metal diborides, or any combination thereof; or (iv) Any combination of terms (i) to (iii).

28. The method according to claim 23, wherein: The maximum cross-sectional dimension of each third protrusion and / or each fourth protrusion in a plane substantially perpendicular to the first direction is less than or equal to 500 μm; The maximum cross-sectional dimension of each third protrusion and / or each fourth protrusion is in the range of 1-100 μm, including 1 μm and 100 μm; The length of each third protrusion and / or each fourth protrusion along the first direction is greater than 1 mm; The length of each third protrusion and / or each fourth protrusion is in the range of 10-100 mm, inclusive; or Any combination of the above items.

29. The method of claim 23, further comprising, prior to the generation: The first electrode is formed by cutting a portion from a first fabric comprising woven carbon fibers or metal fibers, the first substrate being the remaining portion of the first fabric after cutting, and a plurality of first protrusions and / or a plurality of third protrusions being carbon fibers or metal fibers exposed from the cut surface of the remaining portion of the first fabric; and / or The second electrode is formed by cutting a portion of a second fabric, including woven carbon fiber or metal fiber, the second base layer being the remaining portion of the second fabric after cutting, and a plurality of second protrusions and / or a plurality of fourth protrusions being carbon fiber or metal fiber exposed from the cut surface of the remaining portion of the second fabric.

30. The method according to claim 29, wherein, The remaining portion of the first fabric and / or the remaining portion of the second fabric includes a plurality of woven carbon fibers or metal fibers extending in a second direction in a plane substantially perpendicular to the first direction.

31. The method of claim 23, further comprising, prior to the generation: The first electrode is formed by roughening the surface of a first fabric containing woven carbon fibers or metal fibers. A first substrate layer is the main body of the first fabric. Multiple first protrusions and / or multiple third protrusions are carbon fibers or metal fibers broken at the surface of the main body of the first fabric after roughening, and / or carbon fibers or metal fibers exposed from the surface of the main body of the first fabric; and / or The second electrode is formed by roughening the surface of a second fabric containing woven carbon fibers or metal fibers. The second base layer is the main body of the second fabric. The plurality of second protrusions and / or the plurality of fourth protrusions are carbon fibers or metal fibers broken at the surface of the main body of the second fabric after roughening and / or carbon fibers or metal fibers exposed from the surface of the main body of the second fabric.

32. The method according to claim 31, wherein, The main body portion of the first fabric and / or the main body portion of the second fabric includes a plurality of woven carbon fibers or metal fibers extending in a second direction in a plane substantially perpendicular to the first direction.

33. The method of claim 23, further comprising, prior to the generation: Multiple first protrusions are formed on the first base layer; Multiple third protrusions are formed on the first basal layer; Multiple second protrusions are formed on the second base layer; Multiple fourth protrusions are formed on the second basal layer; or Any combination of the above items.

34. The method according to claim 33, wherein, Forming multiple first protrusions, multiple second protrusions, multiple third protrusions, and / or multiple fourth protrusions includes using 3D printing.

35. The method according to claim 34, wherein, The 3D printing includes laser-based direct energy deposition or laser powder bed melting.

36. The method according to claim 1, wherein, The first electrode, the second electrode, or both have a non-planar geometry.

37. The method according to claim 1, wherein: The surface area of ​​the second electrode facing the gap is greater than the surface area of ​​the first electrode facing the gap; and The method further includes, during generation, moving either the first electrode or the second electrode relative to the other electrode to change the position of the generated volumetric plasma.

38. The method of claim 1, further comprising, prior to or simultaneously with the generation, placing one or more precursors in or near the gap between the first electrode and the second electrode, such that volumetric plasma heats the one or more precursors to form one or more products.

39. The method of claim 1, further comprising, during generation, flowing one or more gases and / or one or more precursors through a volumetric plasma, such that the volumetric plasma heats the one or more gases and / or the one or more precursors to form one or more products.

40. The method according to claim 39, wherein, The arrangement of the first and second electrodes is such that the thickness of the gap along the first direction is at a non-zero angle relative to the direction of gravity, so that gravity facilitates the flow of one or more precursors in the gap.

41. The method according to claim 39, wherein, The flow includes delivering one or more precursors into a volumetric plasma using a carrier gas and / or a substrate.

42. The method according to claim 41, wherein, The carrier gas includes an inert gas.

43. The method according to any one of claims 38-42, further comprising: Stop generating volumetric plasma; Remove one or more products from the volumetric plasma; Remove the volumetric plasma away from one or more products; or Any combination of the above items.

44. The method of claim 43, further comprising: Actively cool one or more products; Exposing one or more products to an airflow in order to break them down into smaller droplets; or Both of the above.

45. The method according to claim 1, wherein, The generation includes: Volumetric plasma is initiated by applying a voltage when the gap between the first and second electrodes is at a first distance. Moving the first electrode away from the second electrode and / or moving the second electrode away from the first electrode; and The activated volumetric plasma is maintained by applying a voltage when the gap between the first and second electrodes is greater than a first distance.

46. ​​The method according to claim 1, wherein, The generation process allows the volumetric plasma to be maintained in the same volume for at least 10 minutes.

47. The method according to claim 1, wherein, The temperature of a volumetric plasma is uniformly distributed in space.

48. The method according to any one of claims 1, 20, and 23, wherein: One, part or all of the first protrusion, the second protrusion, the third protrusion and the fourth protrusion have a substantially one-dimensional tip at their end near or within the gap; One, part or all of the first protrusion, the second protrusion, the third protrusion and the fourth protrusion have substantially two-dimensional tips at their ends near or within the gap; One, part or all of the first, second, third and fourth protruding portions have a blunt tip at their end near or within the gap; or Any combination of the above items.

49. A system configured to perform the method of any one of claims 1-48.

50. A system comprising: A first electrode includes a first base layer and a plurality of first protrusions, the first base layer including a first conductive material, at least a portion of the first protrusions including a second conductive material, and the melting temperature of the first conductive material and the melting temperature of the second conductive material being at least 1000K. The second electrode is separated from the first electrode by a gap, and a plurality of first protrusions extend from the first substrate layer toward the second electrode along a first direction; A power source, electrically coupled to the first and second electrodes; as well as A control system operatively coupled to and configured to control the operation of a power source, the control system comprising one or more processors and a computer-readable storage medium storing instructions which, when executed by the one or more processors, cause the power source to apply a voltage between a first electrode and a second electrode, thereby generating a volumetric plasma in or near a gap, the volumetric plasma having a temperature in the range of 1000-8000K, including 1000K and 8000K.

51. The system according to claim 50, wherein: The maximum cross-sectional dimension of each first protrusion in a plane substantially perpendicular to the first direction is less than or equal to 500 μm; The length of each first protrusion along the first direction is less than or equal to 1 cm; The interval between each first protrusion and an adjacent first protrusion in a plurality of first protrusions is less than or equal to 1 mm; or Any combination of the above items.

52. The system according to claim 51, wherein: The maximum cross-sectional dimension of each first protrusion is in the range of 1-100 μm, including 1 μm and 100 μm; The length of each first protrusion is in the range of 200-500 μm, including 200 μm and 500 μm; The spacing between adjacent first protrusions is less than or equal to 100 μm; The density of the first protruding part is at least 10. 4 pcs / cm 2 ;or Any combination of the above items.

53. The system according to claim 52, wherein, The spacing between adjacent first protrusions is in the range of 1-50 μm, including 1 μm and 50 μm.

54. The system according to claim 50, wherein, The thickness of the gap along the first direction is in the range of 1 mm to 1 cm, including 1 mm and 1 cm.

55. The system according to claim 50, wherein, The power supply is configured to apply a direct current (DC) voltage, an alternating current (AC) voltage, or a pulse voltage waveform between the first electrode and the second electrode.

56. The system according to claim 55, wherein, The computer-readable storage medium stores additional instructions that, when executed by one or more processors, cause the power supply to perform the following: A peak voltage of less than or equal to 100V is applied between the first electrode and the second electrode to generate volumetric plasma; A peak current of less than or equal to 100 A is applied between the first and second electrodes to generate volumetric plasma; or Both of the above.

57. The system according to claim 50, wherein, The computer-readable storage medium stores additional instructions that, when executed by one or more processors, also cause the power supply to perform the following: Volumetric plasma is initiated by applying a first direct current (DC) voltage, a first alternating current (AC) voltage, or a first pulse voltage waveform between the first electrode and the second electrode. as well as The initiated volumetric plasma is maintained by applying a second DC voltage, a second AC voltage, or a second pulse voltage waveform between the first and second electrodes. The absolute value of the peak voltage of the second DC voltage, the second AC voltage, or the second pulse voltage waveform is less than the absolute value of the peak voltage of the first DC voltage, the first AC voltage, or the first pulse voltage waveform.

58. The system according to claim 57, wherein: The absolute value of the peak voltage of the first DC voltage, the first AC voltage, or the first pulse waveform is in the range of 10-100V, including 10V and 100V. The absolute value of the peak voltage of the second DC voltage, the second AC voltage, or the second pulse waveform is in the range of 10-50V, inclusive; or Both of the above.

59. The system according to claim 50, wherein, The dimensions of the first and second electrodes are such that the size of the plasma generated along the second direction is in the range of 1 mm to 100 cm, including 1 mm and 100 cm, and the second direction lies in a plane substantially perpendicular to the first direction.

60. The system according to claim 50, wherein, The system is configured to generate volumetric plasma at pressures ranging from 1 Torr to 10 atm, the range including 1 Torr and 10 atm.

61. The system according to claim 50, wherein, The first conductive material is the same as the second conductive material.

62. The system according to claim 50, wherein, The first conductive material, the second conductive material, or both include refractory metals, refractory metal alloys, or both of the foregoing.

63. The system according to claim 50, wherein, The first conductive material, the second conductive material, or both include metal carbides, silicon carbide, metal nitrides, metal diborides, or any combination thereof.

64. The system according to claim 50, wherein: The second electrode includes a second base layer and a plurality of second protrusions extending from the second base layer toward the first electrode along a first direction; The second substrate layer includes a third conductive material; At least a portion of the second protrusion includes a fourth conductive material; as well as The melting temperature of the third conductive material and the melting temperature of the fourth conductive material are at least 1000K.

65. The system according to claim 64, wherein, At least one of the first to fourth conductive materials is the same as another of the first to fourth conductive materials.

66. The system according to claim 64, wherein: At least a portion of the first protrusion has a tapered end. At least a portion of the second protrusion, each of the second protrusions having a tapered end; or Both of the above.

67. The system according to claim 50, wherein: The first electrode further includes a plurality of third protrusions that extend further from the first substrate layer toward the second electrode along a first direction than the plurality of first protrusions, and at least a portion of the third protrusions are formed of a fifth conductive material; The second electrode includes a plurality of fourth protrusions extending from the second substrate layer toward the first electrode along a first direction, at least a portion of the fourth protrusions being formed of a sixth conductive material; At least one third protrusion contacts at least one fourth protrusion in the gap, or the distance between the third protrusion and the fourth protrusion does not exceed 5 μm; as well as The melting temperature of the fifth conductive material and the melting temperature of the sixth conductive material are at least 1000K.

68. The system according to claim 67, wherein, The computer-readable storage medium stores additional instructions, which, when executed by one or more processors, further cause the power supply to perform the following: Volumetric plasma is initiated by gas discharge between the third and fourth protrusions; as well as The initiated volumetric plasma is maintained by gas discharge between the first and second protrusions.

69. The system according to claim 68, wherein, The computer-readable storage medium stores additional instructions that, when executed by one or more processors, further cause the power supply to apply a first voltage between the first and second electrodes before initiating the volumetric plasma, causing current to flow through a contact portion of at least one of the third and fourth protrusions and causing Joule heating of the contact portion, the Joule heating causing at least one of the third and / or fourth protrusions to break, such that a 1-5 μm gap is formed between at least one of the third protrusions and at least one of the fourth protrusions, the gap including 1 μm and 5 μm.

70. The system according to claim 67, wherein, At least one of the first to sixth conductive materials is the same as another of the first to sixth conductive materials.

71. The system according to claim 67, wherein, One, part or all of the first to sixth conductive materials include: (i) Carbon or graphite; (ii) Refractory metals, refractory metal alloys, or both of the above; (iii) Metal carbides, silicon carbide, metal nitrides, metal diborides, or any combination thereof; or (iv) Any combination of terms (i) to (iii).

72. The system according to claim 67, wherein: The maximum cross-sectional dimension of each third protrusion and / or each fourth protrusion in a plane substantially perpendicular to the first direction is less than or equal to 500 μm; The maximum cross-sectional dimension of each third protrusion and / or each fourth protrusion is in the range of 1-100 μm, including 1 μm and 100 μm; The length of each third protrusion and / or each fourth protrusion along the first direction is greater than 1 mm; The length of each third protrusion and / or each fourth protrusion is in the range of 10-100 mm, inclusive; or Any combination of the above items.

73. The system according to claim 50, wherein, The first electrode, the second electrode, or both may include woven carbon fiber or metal fiber.

74. The system according to any one of claims 50, 64, and 67, wherein, Multiple first protrusions, multiple second protrusions, multiple third protrusions, and / or multiple fourth protrusions comprise a 3D-printed column.

75. The system according to claim 50, wherein, The first electrode, the second electrode, or both have a non-planar geometry.

76. The system of claim 50, further comprising: (i) Constructing a first translation stage to move the first electrode; (ii) Constructing a second translation stage to move the second electrode; or (iii) Items (i) and (ii), The control system is operatively coupled to the first translation stage and / or the second translation stage, and is configured to control the operation of the first translation stage and / or the second translation stage. The computer-readable storage medium stores additional instructions that, when executed by one or more processors, cause a first translation stage and / or a second translation stage to move one of the first and second electrodes relative to the other electrode.

77. The system according to claim 76, wherein: The surface area of ​​the second electrode facing the gap is greater than the surface area of ​​the first electrode facing the gap; and The computer-readable storage medium stores instructions that, when executed by one or more processors, cause a first translation stage and / or a second translation stage to move one of the first and second electrodes relative to the other electrode to change the position of the volumetric plasma.

78. The system according to claim 76, wherein, The computer-readable storage medium stores instructions that, when executed by one or more processors, cause the following to be performed: The first translation stage and / or the second translation stage position the first electrode and the second electrode such that the gap is at a first distance; The power source initiates volumetric plasma by applying voltage when the gap between the first electrode and the second electrode is at a first distance. After the volumetric plasma is initiated, the first translation stage and / or the second translation stage are used to move the first electrode and the second electrode away from each other; as well as The power source maintains the initiated volumetric plasma by applying voltage when the gap between the first electrode and the second electrode is greater than a first distance.

79. The system according to claim 50, wherein, The arrangement of the first electrode and the second electrode is such that the thickness of the gap along the first direction is at a non-zero angle relative to the direction of gravity.

80. The system according to any one of claims 50, 64 and 67, wherein: One, part or all of the first protrusion, the second protrusion, the third protrusion and the fourth protrusion have a substantially one-dimensional tip at their end near or within the gap; One, part or all of the first protrusion, the second protrusion, the third protrusion and the fourth protrusion have substantially two-dimensional tips at their ends near or within the gap; One, part or all of the first, second, third and fourth protruding portions have a blunt tip at their end near or within the gap; or Any combination of the above items.

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