Radio-frequency inductively coupled plasma (RF-ICP) torch

Abstract

A radio-frequency plasma torch is provided. The radio-frequency plasma torch comprises a torch housing with a torch channel, a dielectric sheath, an induction coil that is circumferentially disposed around the dielectric sheath, where the induction coil generates an alternating, high-gradient magnetic field, and at least one conductive rod that is connected to an external voltage source for generating a high-voltage spark discharge. The high-voltage spark discharge and the alternating, high-gradient magnetic field collectively ionize the at least one plasma forming gas for generating a flow of plasma within the torch channel. The plasma torch also includes an impeller unit that is rotatably mounted within the torch channel of the torch housing, proximate the inlet section of the torch housing, such that when the impeller unit is driven to rotate, the rotation of the turbine induces a reverse vortex flow of plasma forming gas within the torch channel.

Description

RADIO-FREQUENCY INDUCTIVELY COUPLED PLASMA (RF- ICP) TORCHCross-Reference to Related Applications

[0001] This application claims the priority benefit of the following U.S. Provisional Patent Applications, each of which is incorporated by reference: U.S.: Provisional Patent Application No. 63 / 684,853 entitled “RADIO-FREQUENCY PLASMA TORCH” filed August 19, 2024, and U.S. Provisional Patent Application No. 63 / 685,148 entitled “RADIO-FREQUENCY PLASMA TORCH” filed August 20, 2024.Field of the Disclosure

[0002] The present disclosure relates generally to plasma generation system. In particular, the disclosure relates to a radio-frequency (RF) inductive coupled plasma torch.Background of the Disclosure

[0003] Plasma that is generated by inductively coupled radio frequency (RF) systems, has been well established since the mid-1900s. RF plasma technology has gained significant interest for various purposes, ranging from small-scale plasma systems used for elemental analysis to large-scale power installations for testing materials in the aerospace industry. Induction RF plasma technologies have also found extensive application in the fiber optics sector and, more recently, in the production and treatment of advanced materials, such as high-purity spherical powders in nano- and micron sizes. The successful functioning of the induction plasma torch is, at least in part, based on the torch’s capacity to regulate the airflow dynamics within the discharge of the plasma. Various flow arrangements for stabilizing the plasma have been devised throughout the years. Amongst these various flow arrangements is a flow pattern referred to as reverse vortex flow.

[0004] Reverse vortex flow within RF plasma torches refers to a particular flow pattern of the plasma gas inside the torch. In a typical RF plasma torch, the plasma gas is injected through a central tube and exits through a surrounding annular channel. In a reverse vortex configuration, the plasma gas flow is reversed, meaning it enters through the annular channel and exits through the central tube. The importance of the reverse vortex configuration lies in its ability to enhance the efficiency and performance of RF plasma torches. It promotes better mixing of the plasma gas, leading to improved heat transfer and higher temperatures within the plasma. This configuration also facilitates better control over the plasma shape and stability. Reverse vortex RF plasma torches find applications in several fields. Some of the notable applications include material synthesis, coating and surface modification, and waste treatment.

[0005] In applications for material synthesis, the high temperatures achieved in reverse vortex plasma torches enable efficient synthesis of advanced materials, such as nanoparticles, microparticles, and high-purity powders. The controlled plasma environment allows for precise control over particle size, morphology, and composition. In applications for coating and surface Modification, reverse vortex plasma torches can be used for coating and modifying the surfaces of various materials. The high-energy plasma facilitates the deposition of thin films and coatings, enhancing the properties and functionality of the treated surfaces. Finally, in applications for waste treatment, reverse vortex plasma torches can be employed in waste treatment processes, such as hazardous waste destruction and pollution control. The high temperatures and reactive plasma environment enable efficient decomposition and neutralization of toxic substances.

[0006] Despite the advantages provided by reverse vortex RF plasma torches, these torch designs also face certain challenges and problems. First, the design of existing reverse vortex RF plasma torches are quite complex. Creating and maintaining a reverse vortex flow in RF plasma torches requires careful designconsiderations. It involves intricate geometries and precise control of gas flow rates, velocities, and temperatures. Achieving the desired flow pattern often necessitates advanced computational fluid dynamics (CFD) simulations and experimental optimization.

[0007] It is also challenging to maintain a stable reverse vortex flow pattern within the plasma torch. These reverse vortex flow patterns can be sensitive to changes in operating conditions, such as gas composition, pressure, and power input. Variations in these parameters can affect the stability and effectiveness of the reverse vortex, requiring continuous monitoring and adjustment. While the reverse vortex flow aims to stabilize the plasma discharge, the very nature of the flow can also introduce additional challenges. Unfavorable interactions between the reverse vortex and electromagnetic fields can potentially lead to instabilities or disruptions in the plasma, requiring careful balancing of the system parameters.

[0008] Lastly, due to the high degree of complexity within RF plasma torches that are capable of produce reverse vortex flow patterns, the maintenance and requirements for these torches can be quite high. The intricate flow pattern of the reverse vortex may require additional maintenance and cleaning procedures to prevent blockages or deposits within the torch and thereby maintain long-term stability and efficient performance of the RF plasma torch.

[0009] Therefore, a new design for an RF plasma torch is needed that can produce stable, high-temperature plasma flows with a stable, reverse vortex flow pattern.

[0010] The background herein is included solely to explain the context of the disclosure. This is not to be taken as an admission that any of the material referred to was published, known, or part of the common general knowledge as of the priority date.Summary of the Disclosure

[0011] According to an aspect, there is provided a radio-frequency (RF), inductive plasma torch comprising: a torch housing that defines a torch channel therewithin and that includes at least one inlet for injecting at least one plasma forming gas into the torch channel, the at least one inlet being positioned at an inlet section of the torch housing; a dielectric sheath that is positioned within, and which extends along a length, of the torch channel; an induction coil that is circumferentially disposed around a length of the dielectric sheath, the induction coil including first and second ends that are operatively connected to an external RF power source for receiving an alternating RF current therefrom, the flow of the alternating RF current in the induction coil generating an alternating electric field therefrom, within the torch channel; at least one conductive rod that is connected to the inlet section of the torch housing and that extends along a portion of the torch channel within the dielectric sheath, the at least one conductive rod will affect by the electric field of the RF power supply and heat up and causes a heat up of the plasma forming gas and reduces its ionization potential to ignite the plasma at low power; and an impeller unit that is rotatably mounted within the torch channel of the torch housing, proximate the inlet section of the torch housing, the impeller unit being sized and oriented relative to the torch channel such that when the impeller unit is driven to rotate within the torch channel, the rotation of the turbine induces a reverse vortex flow of the at least one plasma forming gas within the torch channel.

[0012] According to another aspect, there is provided a radio-frequency, inductive plasma torch comprising: a torch housing that defines a torch channel therewithin and that includes at least one inlet for injecting at least one plasma forming gas into the torch channel, the at least one inlet being positioned at an inlet section of the torch housing; a dielectric sheath that is positioned within, and which extends along a length, of the torch channel; an induction coil that is circumferentially disposed around a length of the dielectric sheath, the induction coil including first and secondends that are operatively connected to an external RF power source for receiving an alternating RF current therefrom, the flow of the alternating RF current in the induction coil generating an alternating, electric field therefrom, within the torch channel; the igniter pins that are mounted in the torch channel and that extend along a length of the inner dielectric sheath, helps to reduces the ionization potential of the plasma forming gas and ignite the plasma in atmospheric pressure at low RF power, for generating a flow of plasma within the torch channel; and an impeller unit that is rotatably mounted within the torch channel of the torch housing, proximate the inlet section of the torch housing, the impeller unit being sized and oriented relative to the torch channel such that when the impeller unit is driven to rotate within the torch channel, the rotation of the turbine induces a reverse vortex flow of the at least one plasma forming gas within the torch channel.Brief Description of the DrawingsEmbodiments will now be described, by way of example only, with reference to the attached Figures, wherein:

[0013] Figure 1 shows a front view of an embodiment of the RF plasma torch of the present disclosure;

[0014] Figure 2 shows a perspective view of the embodiment of the RF plasma torch provided in Figure 1 ;

[0015] Figure 3 shows another front view of the embodiment of the RF plasma torch provided in Figure 1 ;

[0016] Figure 4 shows a front, section view of the embodiment of the RF plasma torch provided in Figure 1 , taken along the section line A-A;

[0017] Figure 5 shows another front, section view of the embodiment of the plasma torch provided in Figure 1 , take along the section line A-A;

[0018] Figure 6 shows a perspective view of an embodiment of the impeller head of the impeller unit;

[0019] Figure 7 shows a perspective view of the torch head of the embodiment of the RF plasma torch in Figure 1 , where the housing of the torch head is partially transparent;

[0020] Figure 8 shows another perspective view of the torch head of the embodiment of the RF plasma torch in Figure 1 , where the housing of the torch head is partially transparent;

[0021] Figure 9 shows another perspective view of the torch head of the embodiment of the RF plasma torch in Figure 1 ;

[0022] Figure 10 shows a flow chart of an embodiment of the optimization process for optimizing the design of the RF plasma torch of the present disclosure;

[0023] Figure 11 shows a plot of impeller blade length versus torch body diameter for various partially optimized designs of the RF plasma torch of the present disclosure;

[0024] Figure 12 shows a plot of torch body length versus torch body diameter for various partially optimized designs of the RF plasma torch of the present disclosure;

[0025] Figure 13A shows a plot of plasma temperature versus axial distance along the torch for different gas entry angles (cp) under a 5 standard liters per minute (SLPM) Argon (Ar) flow;

[0026] Figure 13B shows a plot of heat flux versus axial distance along the torch for different gas entry angles (cp) under a 5 standard liters per minute (SLPM) Argon (Ar) flow;

[0027] Figure 13C shows a 2-D graphical illustration of plasma temperature contours for the embodiment of the RF plasma torch in Figure 20A;

[0028] Figure 13D shows a 2-D graphical illustration of heat flux contours for the embodiment of the RF plasma torch in Figure 20A;

[0029] Figure 14A shows a plot of plasma temperature versus axial distance along the torch for different gas entry angles (cp) under varying rate of Argon (Ar) flow;

[0030] Figure 14B shows a plot of heat flux versus axial distance along the torch for different gas entry angles (cp) under varying rates of Argon (Ar) flow;

[0031] Figure 14C shows a 2-D graphical illustration of plasma temperature contours for the embodiment of the RF plasma torch in Figure 20A;

[0032] Figure 14D shows a 2-D graphical illustration of heat flux contours for the embodiment of the RF plasma torch in Figure 20A;

[0033] Figure 15A shows a plot of plasma temperature versus axial distance along the torch for the design of the torch with and without the nozzle;

[0034] Figure 15B shows a plot of heat flux versus axial distance along the torch for the design of the torch with and without the nozzle;

[0035] Figure 15C shows a 2-D graphical illustration of plasma temperature contours for the embodiment of the RF plasma torch in Figure 20A;

[0036] Figure 15D shows a 2-D graphical illustration of heat flux contours for the embodiment of the RF plasma torch in Figure 20A;

[0037] Figure 16A shows a plot of plasma temperature versus axial distance along the torch for varying nozzle diameters on the torch;

[0038] Figure 16B shows a plot of heat flux versus axial distance along the torch for varying nozzle diameters on the torch;

[0039] Figure 16C shows a 2-D graphical illustration of plasma temperature contours for the embodiment of the RF plasma torch in Figure 20A;

[0040] Figure 16D shows a 2-D graphical illustration of heat flux contours for the embodiment of the RF plasma torch in Figure 20A;

[0041] Figure 17A shows a plot of the relationship between plasma temperature with axial distance from the torch nozzle at different gas inlet angles, 10 SLPM gas flow rate, 770 W RF power, and torch body of radius 10 mm;

[0042] Figure 17B shows a plot of the relationship between total heat flux with axial distance from the torch nozzle at different gas inlet angles, 10 SLPM gas flow rate, 770 W RF power, and torch body of radius 10 mm;

[0043] Figure 17C shows a plot of the relationship between the gas inlet angle and the swirl number;

[0044] Figure 18A shows a plot of plasma temperature versus axial distance along the torch for various torch radii;

[0045] Figure 18B shows a plot of heat flux versus axial distance along the torch for various torch radii;

[0046] Figure 18C shows a 2-D graphical illustration of plasma temperature contours for the embodiment of the RF plasma torch in Figure 20A;

[0047] Figure 18D shows a 2-D graphical illustration of heat flux contours for the embodiment of the RF plasma torch in Figure 20A;

[0048] Figure 19A shows a plot of the relationship between RF power of the torch and the plasma temperature generated at various positions along the length of the torch;

[0049] Figure 19B shows a plot of the relationship between RF power of the torch and the total heat flux generated at various positions along the length of the torch;

[0050] Figure 19C shows a schematic diagram of the computational mesh used in the simulations of Examples 4 and 5;

[0051] Figure 20A shows a schematic of the plasma torch geometry used in the simulations of Examples 4 and 5 where the plasma torch body does not have a nozzle; and

[0052] Figure 20B shows a schematic of the plasma torch geometry used in the simulations of Examples 4 and 5 where the plasma torch body has a nozzle added to it.Detailed Description of the Embodiments

[0053] For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the Figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in orderto provide a thorough understanding of the embodiment or embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. It should be understood at the outset that, although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described below.

[0054] Various terms used throughout the present description may be read and understood as follows, unless the context indicates otherwise: “or” as used throughout is inclusive, as though written “and / or”; singular articles and pronouns as used throughout include their plural forms, and vice versa; similarly, gendered pronouns include their counterpart pronouns so that pronouns should not be understood as limiting anything described herein to use, implementation, performance, etc. by a single gender; “exemplary” should be understood as “illustrative” or “exemplifying” and not necessarily as “preferred” over other embodiments. Further definitions for terms may be set out herein; these may apply to prior and subsequent instances of those terms, as will be understood from a reading of the present description. It will also be noted that the use of the term “a” or “an” will be understood to denote “at least one” in all instances unless explicitly stated otherwise or unless it would be understood to be obvious that it must mean “one”.

[0055] As used herein, the terms “comprises” and “comprising” are to be construed as being inclusive and open ended, and not exclusive. Specifically, when used in the specification and claims, the terms “comprises” and “comprising”, and variations thereof mean the specified features, steps or components are included.These terms are not to be interpreted to exclude the presence of other features, steps or components.

[0056] As used herein, the terms “about” and “approximately” are meant to cover variations that may exist in the upper and lower limits of the ranges of values, such as variations in properties, parameters, and dimensions.

[0057] Modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For example, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. As used in this document, “each” refers to each member of a set or each member of a subset of a set.

[0058] The embodiments described herein are exemplary (e.g., in terms of materials, shapes, dimensions, and constructional details) and do not limit by the claims appended hereto and any amendments made thereto. Persons skilled in the art will appreciate that there are yet more alternative implementations and modifications possible, and that the following examples are only illustrations of one or more implementations. The scope of the disclosure, therefore, is only to be limited by the claims appended hereto and any amendments made thereto.

[0059] Any reference to upper, lower, top, bottom or the like are intended to refer to an orientation of a particular element during use of the claimed subject matter and not necessarily to its orientation during shipping or manufacture. The upper surface of an element, for example, can still be considered its upper surface even when the element is lying on its side.

[0060] Referring to Figures 1 to 2 there is provided a radio-frequency (RF), inductive plasma torch (referred to hereinafter as an RF plasma torch 200) according to an embodiment of the present disclosure. The RF plasma torch 200 generallycomprises a torch housing 210, a dielectric sheath 160, an induction coil 270, at least one conduction element and an impeller unit 240. As shown in Figures 1 to 8C, the RF plasma torch 200 also includes the impeller unit 240. The impeller unit 240 is rotatably mounted within the torch channel 218 of the torch housing 210 such that at least part of the impeller unit 240 can rotate relative to the torch channel 218. The impeller unit 240 is generally positioned, proximate the inlet section of the torch housing 210. The impeller unit 240 is sized and oriented relative to the torch channel 218 such that when the impeller unit 240 is driven to rotate within the torch channel 218, the rotation of the turbine induces a reverse vortex flow of the at least one plasma forming gas within the torch channel 218.

[0061] The reverse vortex flow pattern within the RF plasma torch 200 of the present disclosure refers to a particular flow pattern of the plasma gas inside the torch channel 218. In a typical RF plasma torch 200, the plasma gas is injected through a central tube and exits through a surrounding annular channel. In a reverse vortex configuration, the plasma gas flow is reversed, meaning it enters along a substantially annular path exits through a more centrally disposed outlet.

[0062] By providing an impeller unit 240 within the RF plasma torch 200 that induces a reverse vortex flow pattern of the plasma forming gas within the torch channel 218, better mixing of the plasma-forming gas within the torch channel 218 can occur, which can in turn lead to improved heat transfer and higher temperatures within the flow of plasma formed from the ionization of the plasma-forming gas. The inducement of the reverse vortex flow of the plasma-forming gas can also facilitate better control over the shape and stability of the flow of plasma.

[0063] As provided above, the RF plasma torch 200 includes the torch housing 210 with the torch channel 218 defined therethrough. The torch housing 210 functions as the base structure for the RF plasma torch 200 and provides a framework to which various components and other elements of the RF plasma torch 200 can be attached.

[0064] Various forms and structured of the torch housing 210 are provided by the present disclosure.

[0065] The torch housing 210 can be composed of various materials, such as at least one metal material or at least one polymer material.

[0066] In an embodiment, the torch housing 210 is composed of a metal material with a high thermal stability, such as stainless steel.

[0067] In an embodiment, the torch housing 210 and the torch channel 218 within the torch housing 210 each have a substantially cylindrical form. In this same embodiment, the dielectric sheath 160 also has a substantially tubular form, and the torch channel 218 and dielectric sheath 160 are arranged so as to be substantially concentric with one another.

[0068] In embodiments, the torch housing 210 defines a torch channel 218 therewithin. The torch housing 210 includes at least one inlet 220 for injecting at least one plasma forming gas into the torch channel 218, where the at least one inlet 220 is positioned at an inlet section of the torch housing 210. The induction coil 270 includes first and second ends that are operatively connected to an external RF power source (not shown) for receiving an alternating RF current therefrom. This flow of the alternating RF current within the induction coil 270 generates an alternating, magnetic field from the induction coil 270, within the torch channel 218. In at least some embodiments, the magnetic field generated from the induction coil 270 is a “high-gradient” magnetic field

[0069] Various arrangements and configurations of the at least one inlet 220 are also provided by the present disclosure.

[0070] In at least some embodiments, the at least one inlet 220 is formed on a sidewall 214 of the torch housing 210.

[0071] 21 Oln at least some embodiments, the at least one inlet 220 of the torch housing 210 is structured as a plurality of inlets 220. The plurality of inlets 220 can, in at least some additional embodiments, be structured as a plurality of gas flow linesthat are mounted through a distributor head, where the distributor head is integrated as part of the inlet section of the torch housing 210. In this embodiment, each of the plurality of gas flow lines defines one of the plurality of inlets 220.

[0072] In at least some embodiments of the RF plasma torch 200, the at least one inlet 220 is oriented relative to the torch channel 218 such that the at least one plasma forming gas is injected along an inner surface of the dielectric sheath 160 for producing a vortex flow of the at least one plasma forming gas within the dielectric sheath 160.

[0073] In an embodiment, the torch housing 210 further includes at least one outlet. The at least one outlet may be disposed at various positions on the torch housing 210 and is generally provided for expelling the flow of plasma from the torch housing 210. The at least one inlet 220 can similarly be disposed at various positions along torch housing 210 such that various flow paths between the at least one inlet 220 and the at least on outlet can be defined within the torch housing 210, along the torch channel 218.

[0074] In an additional embodiment, the inlet section of the torch housing 210 is defined at a first end of the torch housing 210 such that the at least one inlet 220 is defined at the first end of the torch housing 210, and the at least one outlet is formed at a second end of the torch housing 210 that is opposite the first end of the torch housing 210.

[0075] The RF plasma torch 200 as disclosed herein may use distinct types and compositions of gases as the at least one plasma forming gas. In an embodiment, the at least one plasma forming gas is any one of an oxygen-containing gas, a mixture of oxygen-containing gases, or a mixture of water vapor and inert gases. It is generally preferable to have a composition of the at least one plasma forming which has a very low amount of oxygen or water vapor contamination.

[0076] In an additional embodiment, the at least one plasma forming gas is a plurality of plasma forming gases.

[0077] The at least one plasma forming gas can also, in various embodiments, include inert gases like argon and helium, or hydrocarbon species such as acetylene or methane, or mixtures thereof. This allows for precise control of the plasma temperature and particle density and provides the opportunity to incorporate materials directly in the plasma-forming gas.Impeller unit

[0078] As noted above, the provision of an impeller unit 240 within the RF plasma torch channel 218 can optimize the flow pattern of the plasma-forming gas within the torch channel 218 and thereby generate desirable flow patterns of plasma out of the system. The impeller unit 240 of the RF plasma torch 200 is structured to optimize the flow pattern of the plasma-forming gas in several ways.

[0079] First, the impeller unit 240 provides a means to control the flow of the plasma-forming gas. By structuring the RF plasma torch 200 such that the impeller unit 240 is positioned within the torch channel 218, more refined control of the flow of the plasma-forming gas within the torch channel 218 can be realized. By adjusting the design and configuration of vanes 244 of the impeller unit 240 or adjusting the rotational speed of the impeller head 242 and / or other parameters of the impeller unit 240, the flow pattern and intensity of plasma-forming gas within the torch channel 218 can be accurately controlled. This control allows for fine-tuning the plasma characteristics and optimization of the flow of plasma generated within the RF plasma torch 200.

[0080] The impeller unit 240 is generally free to rotate, and the impeller unit 240 does so under the effect of the gas speed. The impeller unit 240 may work to create reverse vortex flow patterns with the vortex flow within the torch chamber, while the impeller unit 240 may also help to ensure that the gas rotation in the torch chamber sustains to the end of the torch and does not stop in the middle. As presented in the Examples of the present disclosure, the dimensions of the impeller unit 240 werestudied, and the relation between the torch diameter and its dimensions is displayed in Figure 17A.

[0081] Finally, by providing the impeller unit 240 within the torch channel 218 of the torch housing 210, a reverse vortex flow pattern of the plasma gas can be generated within the torch channel 218. As noted above, the impeller unit 240 is rotatably connected within torch channel 218 to rotate therewithin. The rotation of the impeller unit 240 helps create a corresponding rotational motion of the plasma gas. The rotational motion of the impeller head 242 effectively produces a swirling motion of both any air in the torch channel 218 and the plasma-forming gas injected into the torch channel 218 via the at least one inlet 220. This swirling motion propagates throughout the torch channel 218 and, as the plasma-forming gas passes through the vanes 244 of the impeller head 242, the plasma-forming gas gains angular momentum and starts rotating. The rotation of the plasma-forming gas creates the desired reverse vortex flow pattern, where the gas enters through the more annularly positioned inlet(s) 220 and exits through a more centrally positioned outlet while flowing in the reverse vortex flow pattern.

[0082] The reverse vortex flow pattern within the torch channel 218 improves the performance of the RF plasma torch 200 in several ways. First, the reverse vortex configuration helps stabilize the plasma. The reverse vortex flow pattern will generate a more well-defined and stable flow pattern of the plasma-forming gas within the torch channel 218. By creating a well-defined and stable flow of the plasma-forming gas, turbulence and fluctuations in the plasma that is generated from the plasma-forming gas can be minimized, resulting in a more stable and reliable flow of plasma. This stability enables the RF plasma torch to produce plasma with consistent plasma properties.

[0083] The reverse vortex configuration within the RF plasma torch 200 also optimizes the interaction between the plasma-forming gas and any annular gas stream provided within the torch channel 218. The rotational motion of the plasma-forming gas in the reverse vortex flow pattern promotes interaction between the central and annular gas streams, leading to improved temperature uniformity and heat transfer efficiency.

[0084] Finally, reverse vortex configuration within the RF plasma torch 200 will enhance the mixing and heat transfer within the torch. The reverse vortex flow pattern will reduce the velocity of the plasma-forming gas within the torch channel 218 and as a result of the reduced velocity, increase the residence time of the plasma-forming gas within the torch channel 218. As described above, the longer residence time enhances the mixing of the plasma-forming gas within the torch channel 218, thereby facilitating better heat transfer within the RF plasma torch 200.

[0085] Various embodiments and specific configurations of the impeller unit 240 will now be described with reference to the drawings.

[0086] The impeller unit 240 of the RF plasma torch 200 may be oriented within the torch channel 218 of the torch housing 210 in various ways such that impeller head 242 may have various orientations and will rotate about various axes relative to a long axis of the torch channel 218. For example, in the specific, non-limiting embodiment provided in Figures 1 to 8C, the impeller unit 240 is mounted within the torch channel 218 such that the impeller head 242 is substantially coaxial to the torch channel 218 (i.e., a rotational axis of the impeller head 242 is substantially coaxial to the long axis of the torch channel 218)

[0087] The impeller head 242 of the impeller unit 240 may also be arranged at various positions within the torch channel 218 so as to optimize the formation of the reverse vortex flow pattern of the plasma-forming gas within the torch channel 218. In an embodiment such as shown in Figures 1 to 5, the impeller head 242 is positioned proximate the at least one inlet 220, near the first end of the torch housing 210 such that the at least one plasma-forming gas is injected into the torch channel 218 proximate the impeller head 242.

[0088] Various structures and arrangements of the impeller head 242 within the impeller unit 240 are also provided by the present disclosure.

[0089] In an embodiment such as shown in Figure 6, the impeller head 242 includes an impeller hub 243, and a plurality of vanes 244 that extends at least partially radially outwards from the impeller hub 243. The plurality of vanes 244 are connected to the impeller hub 243 and extend outward therefrom to form the impeller head 242. In an additional embodiment, the impeller hub 243 includes a number of radial slots, and each of the plurality of vanes 244 is removably mounted within one of the radial slots. The impeller hub 243 also includes a mounting aperture 245 that extends at least partially therethrough. The mounting aperture 245 is provided on the impeller hub 243 for rotatably connected to impeller hub to some element about which the impeller hub 243 can rotate.

[0090] Various configurations and structures of the plurality of vanes 244 mounted to the impeller hub 243 are also provided by the present disclosure.

[0091] For example, in the specific embodiment provided in Figures 6, the impeller head 242 is a radial impeller head 242, and the plurality of guide vanes 244 are a plurality of radial guide vanes 244a. Each radial guide vane 244a of the plurality of radial guide vanes 244a is oriented at an angle relative to a radial plane of the impeller head 242. Said another way, each radial guide vane 244a of the plurality of radial guide vanes 244a has a negative blade angle such that a direction of thrust of the impeller head 242 is oriented substantially towards the first end of the torch housing 210.

[0092] In an alternative embodiment provided Figure 6, impeller head 242 is a radial impeller head 242, and the plurality of vanes 244 of the impeller head 242 are a plurality of straight guide vanes 244b, that have zero blade angles and an airfoillike cross sectional profile.

[0093] In an embodiment, the impeller unit 240 further comprises an impeller shaft. The impeller shaft has a first end that is connected to the impeller head 242and a second end that extends towards the at least one outlet of the torch housing 210.

[0094] In the specific embodiment provided in the impeller shaft 246 is mounted to the impeller hub 243 and is substantially coaxial with the long axis of the torch channel 218.

[0095] In at least some embodiments, the impeller head 242 of the impeller unit 240 is rotatably mounted within the torch channel 218 such that a central, rotational axis of the impeller head 242 is substantially colinear with a central, longitudinal axis of the torch channel 218, and a long axis of impeller shaft is substantially colinear with the central, rotational axis of the impeller head 242.

[0096] In an additional embodiment, the impeller unit 240 may further comprises an impeller disk. The impeller disk may be connected to a second end of the impeller shaft such that the impeller disk is spaced apart from the impeller head 242. Various sizes and spacings of the impeller disk, impeller shaft, and impeller head 242 (including the vanes of the impeller head 242) are provided for in the present disclosure. By providing an impeller disk that is in the path of the gas motion driven by the movement of the impeller head 242, gas (and therefor plasma) backflow is substantially prevented from reaching the impeller head 242 and disturbing gas motion and rotation.

[0097] In at least some embodiments of the present disclosure, the impeller disk of the impeller unit 240 is included within the impeller unit 240 to further optimize the pressure and flow within the torch channel 218. By providing the impeller disk that is spaced apart from the impeller head 242 of the impeller unit 240 and is in between the impeller head 242 and the at least one outlet of the torch housing 210, the reverse vortex flow can be further optimized. This further optimization of the reverse vortex flow pattern can help to produce a more unform flow of plasma within the RF plasma torch 200. This more uniform flow of plasma can produce a more homogeneous plasma jet at the at least one outlet and, in some embodiments, can allow the plasmajet to extend further distances out from the at least one outlet of the RF plasma torch 200.

[0098] In the various embodiments of the impeller unit 240 that include the impeller disk, the positioning of the impeller disk relative to the impeller head 242 and the sizing of the impeller disk relative to a diameter of the torch channel 218 can be optimized to further control the flow of the plasma-forming gas within the torch channel 218.

[0099] In an embodiment, the impeller unit 240 is structured such that a ratio of a diameter of the impeller disk to a diameter of the torch channel 218 is in a range from about 10 cm to about 30 cm.

[0100] In an additional embodiment, the impeller shaft of the impeller unit 240 is sized such that a ratio of a diameter of the impeller disk to a distance between the impeller head 242 and the impeller disk is in a range from about 1 :1 to about 4:1 .Torch structure

[0101] Additional details and exemplary embodiments for the structure of the rest of the RF plasma torch 200 will now be described with reference to the drawings.

[0102] As provided above, the RF plasma torch 200 includes the at least one dielectric sheath 160 that is mounted within the torch housing 210. The at least one dielectric sheath 160 is formed as a generally hollow sheath, and generally defines a “plasma chamber” therewithin, where the flow of plasma initially forms within the plasma chamber.

[0103] In an embodiment, the at least one dielectric sheath 160 is composed of at least one of a quartz material or a ceramic material.

[0104] In an embodiment, the dielectric sheath 160 extends to a predetermined longitudinal position along the torch channel 218, wherein the induction coil 270 is circumferentially disposed about the dielectric sheath 160 such that the induction coil 270 extends from a first longitudinal position to a second longitudinal position along the torch channel 218. In this embodiment, the second longitudinal position is definedbetween the first longitudinal position and the predetermined longitudinal position such that the dielectric sheath 160 extends further along the torch channel 218 than the induction coil 270. By structuring the sheath 160 to extend further along the torch channel 218 than the coil, the formation of the flow of plasma, which forms at least in part due to the magnetic field generated by the induction coil 270, will be generated within the plasma chamber defined within the hollow interior of the dielectric sheath 160.

[0105] In an embodiment, the RF plasma torch 200 is structured such that the dielectric sheath 160 is mounted within the torch channel 218 of the torch housing 210, and a gap exists between an inner wall of the torch housing 210 and an outer surface of the dielectric sheath 160. The gap between the inner wall and outer surface is sufficiently large so that the induction coil 270 can be positioned within the gap and can be circumferentially wrapped around the outer surface of the dielectric sheath 160.

[0106] The induction coil 270 of the RF plasma torch 200 (which may be a water- cooled induction coil in some embodiments) generally includes at least opposing first and second coil ends, and a length of helical coil extending between the first and second coil ends. The induction coil 270 is connected to the external RF power source (not shown) and produces the magnetic field within the plasma chamber of the torch housing 210.

[0107] In an additional embodiment, the induction coil 270 further includes a through channel extending along the length thereof. The through channel is structured to allow a volume of at least one coil cooling fluid to be circulated through an interior of the induction coil 270, and to cool the helical body of the induction coil 270. This can be done while the coil 270 is generating the magnetic field and / or after the coil 270 has generated the magnetic field. The through channel of the induction coil 270 includes an inlet 171 formed on the first coil end and an outlet 173 formedon the second coil end. The inlet 171 and outlet 173 are used for circulating the at least one coil cooling fluid along the through channel.

[0108] In the specific embodiment provided in , the induction coil 270 is composed of at least one metal material and includes a tubular through-passage extending along the length thereof. The induction coil 270 is structured as a water-cooled induction coil 270 where water is the at least one coil cooling fluid. The induction coil 270 also includes at least two types of insulators (e.g., a fibreglass insulator and a thermal insulator for isolating the induction coil 270 from the rest of the RF plasma torch 200 and from at least one coil cooling fluid.

[0109] In some embodiments of the torch housing 210, the tapered, conical section 228 of the torch housing 210 is integrally formed with the hollow, cylindrical torch body 212 and is composed of the same material(s) as the hollow, cylindrical torch body 212.

[0110] The RF plasma torch 200 also includes at least one conductive element that is connected to the inlet section of the torch housing 210. The at least one conductive element extends along a portion of the torch channel 218 within the dielectric sheath 160. The at least one conductive element is operatively connected to an external voltage source (not shown) for generating a high-voltage spark discharge therefrom. The high-voltage spark discharge and the alternating, high- gradient magnetic field collectively ionizing the at least one plasma forming gas for generating a flow of plasma within the torch channel 218.

[0111] In an embodiment, the at least one conductive element 215 is at least one conductive rod.

[0112] In an additional embodiment, the at least one conductive rod extends to a location between the first longitudinal position and the second longitudinal position along the torch channel 218, such that a free, distal end of the at least one conductive rod is disposed within the plasma chamber defined within the at least one dielectric sheath 160.

[0113] The RF plasma torch 200 may be structured in several ways to enhance the usability and user safety of the RF plasma torch 200.

[0114] Examples of the optimization process for selecting specific details of the RF plasma torch 200 are described in Examples 1 , 2, and 3 of the present disclosure.

[0115] As shown in Figures 1 to 5, the RF plasma torch includes the torch housing 210 with the torch chamber 218 defined therein. In embodiments, torch housing 218 may include some or all of the above-described features of the torch housing 210. For example, the torch housing 210 may be composed of a metal material with a high thermal stability, such as stainless steel. Alternatively, the torch housing 210 may include a quartz tube that acts as the torch channel 218.

[0116] In an additional embodiment such as shown in Figures 1 to 5, the torch housing 210 defines the torch channel 218 therewithin, and a conical chamber section and a cylindrical chamber section further define the torch channel 218. The conical chamber section tapers along its length and terminates in a shorter cylindrical tube section with a smaller diameter than the cylindrical tube chamber section.

[0117] In the specific, exemplary embodiment provided in Figures 7 to 8C, the cylindrical tube chamber section has a length of about 200 mm, an internal diameter of about 100 mm, and approximately 5 mm thick walls. The conical chamber section tapers at an approximately 45-degree conical angle (though this angle can be varied). The conical chamber section transitions to the shorter cylindrical tube section, which has a diameter of about 10.40 mm and a wall thickness of about 10 mm. In this specific embodiment, the sizing of the torch housing 210, including the diameters of the inlet tube and outlet nozzle, were set via an optimization process, and a relationship between the inlet and outlet diameters was set to create reverse vortex and maximize swirling strength in a plasma zone defined within the torch housing 210. In at least some other embodiments of the torch housing 210, the conical section 228 of the torch housing 210 is removably connected to the cylindrical torch body 212 but is composed of substantially the same material(s) as the hollow, cylindricaltorch body 212. In still other embodiments, the tapered, conical section 228 is removably connected to the cylindrical torch housing 210, but is composed of different materials than the hollow, cylindrical torch body 212.

[0118] As shown in Figures 1 to 5, the torch housing 210 also includes at least one inlet, which in this embodiment is a gas inlet tube 224. In at least some other embodiments, the at least one inlet may include a plurality of inlets and may be disposed at various positions on the torch housing 210.

[0119] In the specific, exemplary embodiment shown in Figures 1 to 5, the gas inlet tube 224 is fixed with an outer diameter of about 16 mm and an inner diameter of about 10 mm. The gas inlet tube 224 has a length of about 100 mm and a diameter of about 6.00 mm. It is fitted to the torch housing 210 tangentially at an angle of about 30° from the sidewall of the torch, a configuration chosen to initiate gas rotation. In this arrangement, the gas inlet tub 224 is substantially tangential to the hollow, cylindrical torch body 212 of the cylindrical torch housing 210.

[0120] In an additional embodiment such as shown in Figures 1 to 5, the height of the gas inlet tube 224 is set at substantially the same height as the impeller unit 240 for optimized gas distribution. With this arrangement, the gas provided to the torch housing 210 via the gas inlet tube 224 may be passed directly towards the impeller unit 240 within the torch housing 210.

[0121] In an additional embodiment such as shown in Figures 1 to 8, the torch housing 210 is a multi-part torch housing that includes a plurality of releasably connectable parts. The multi-part configuration of the torch housing 210 may, in at least some embodiments, include a torch head 216 that is formed at an inlet end of the torch housing 210 that includes the at least one inlet. An example of the torch head 216 is shown in Figure 9. The torch housing 210 may also include a removable torch nozzle 225 that includes the conical section 228 and an outlet 227 of the torch housing 210.

[0122] In an exemplary embodiment, the torch housing 210 can include the hollow, cylindrical torch body 212 with the removable torch head 216 on a first end thereof and the removable torch nozzle 225 on a second end opposite the first end. Each of the first and second ends of the torch body 212, the removable torch head 216 and the removable torch nozzle 225 are threaded to allow the torch head 216 and torch nozzle 225 to be removably connected to the first and second ends of the cylindrical torch housing 210.

[0123] In the specific, exemplary embodiment provided in Figure 8, the torch head 216 torch head of the RF plasma torch 200 is shown. The torch head 216 includes the gas inlet tube 224, impeller unit 240, and an ignition rod (i.e., the at leas tone conductive element) with a length of about 132 mm and a diameter of about 2 mm.

[0124] As shown in Figures 1 to 5, the induction coil 270 of the RF plasma torch 200 is a conductor tube made of a conductive material that is connected to the RF power supply, and which is circumferentially disposed around a length of the torch housing 210. The induction coil 270 includes the first and second ends that are operatively connected to an external RF power source (not shown) for receiving an alternating RF current therefrom. The induction coil 270 has a helical form that wraps around a length of the torch body 212 and surrounds an exterior of this portion of the torch body 212. The induction coil 270 can be various lengths relative to the length of the torch housing. For example, the length of the induction coil 270 can be such that the induction coil surrounds a partial length of cylindrical chamber section, or a full length of cylindrical chamber section.

[0125] In some embodiments, the induction coil 270 is made of a tube that can be cooled with flowing water and is covered with an insulator. The induction coil 270 may include the inlet 171 , the outlet 173 and the through channel via which flowing water (or other suitable cooling medium) can be circulated.

[0126] The RF plasma torch 200 includes an RF coil 270 that surrounds a portion of the torch body. This RF coil 270 is disposed on the outside of the torch body andhas a helical form that wraps around a length of the torch body. The length of the coil can be varied, such as encompassing a partial length or the full length of the cylindrical chamber section. The RF coil 270 is a conductive tube made of a conductive material (e.g., copper, as in Embodiment 1 ) and is connected to an external RF power supply (not shown).

[0127] In an additional embodiment, the induction coil 270 further includes the through channel extending along the length thereof to allow a volume of at least one coil cooling fluid to be circulated through an interior of the induction coil 270, and to cool the helical body of the induction coil 270. This can be done while the coil 270 is generating the magnetic field and / or after the coil 270 has generated the magnetic field.

[0128] In the specific embodiment provided in Figures 1 to 5, the induction coil 270 is composed of at least one metal material and includes a tubular through channel extending along the length thereof. The induction coil 270 is structured as a water-cooled induction coil 270 where water is the at least one coil cooling fluid. The induction coil 270 also includes at least two types of insulators (e.g., a fiber glass insulator and a thermal insulator for isolating the induction coil 270 from the rest of the RF plasma torch 200 and from the at least one coil cooling fluid.

[0129] In an embodiment such as shown in Figures 7 to 9, the RF plasma torch 200 includes the impeller unit 240 that drives the formation of the reverse vortex flow pattern within the torch channel 218. The impeller unit 240 comprise two or more main components, such as a propeller head 242 that includes a plurality of vanes 244, and an insulated mounting tube 246 that extends through a central portion of the propeller hub 243. The propeller hub 243 may rotate about the insulated mounting tube 246. Again, by providing the impeller unit 240 within the RF plasma torch 200 that induces a reverse vortex flow pattern of the plasma forming gas within the torch channel 218, better mixing of the plasma-forming gas within the torch channel 218 can occur, which can in turn lead to improved heat transfer and highertemperatures within the flow of plasma formed from the ionization of the plasmaforming gas.

[0130] Referring to Figure 8, there is provided a close-up view of the impeller vanes 244 of the impeller head 242. The impeller head 242 includes an impeller hub 243, and the vanes are attached about the circumference of the impeller hub 243 and extend outward therefrom.

[0131] In the specific, exemplary embodiment provided in Figure 8, the propeller head 242 includes the impeller hub 243, and the impeller hub has an approximately 25 mm diameter and a thickness of about 10 mm. The plurality of vanes 244 includes 20 blades, each with a thickness of about 1 mm, a length of about 8 mm, and tilted at an angle of 78.15° relative to a radial plane of the impeller head 242. These specific blade dimensions and angles are optimized to distribute the incoming gas from the inlet tube and generate a uniform airflow, initiating the swirling motion.

[0132] In an additional embodiment, the impeller unit 240 may include an impeller disk 248, which may be similar or substantially the same as the impeller disk 148. The insulated mounting tube 246 (which may also be referred to as the impeller rod) of the impeller unit 240 may connected the impeller head 242 and the impeller disk 248 such that the impeller head 242 and the impeller disk 248 are spaced apart and a planar face of the impeller head 242 is substantially parallel to the planar faces of the impeller disk.

[0133] In an exemplary embodiment, the insulated mounting tube 246 has a diameter of about 5 mm and a length of about 50 mm, and the impeller disk 248 has a thickness of at least about 2 mm and a diameter in a range form about 20 mm to about 80 mm (e.g., 75.86 mm). The impeller disk may be provided in order to further instigate the reverse vortex flow within the torch channel 218 by preventing the flow from extending back towards the impeller unit 240, thereby minimizing disturbance and maintaining the stability of the vortex in the plasma zone.

[0134] While some embodiments of the RF plasma torch 200 may be provided with the impeller disk as part of the impeller unit 240, other embodiments of the impeller unit 240 may be provided without the impeller disk as part of the impeller unit. Referring to Figures 1 to 5, an example RF torch is shown where the impeller unit 240 does not include the impeller disk 148. Said another way, some embodiments of the impeller unit may include the impeller head without the impeller disk.

[0135] The flow of the plasma-forming gas within the torch channel 218 is shown to rotate and reflect on the impeller head thereby disturbing the motion of the gas. In contrast, in the embodiment shown in Figure 4B, the impeller unit 240 includes the impeller disk. The impeller disk effectively blocks and prevents gas from returning to the impeller head 242. While the reflection of gas to the impeller head 242 may seem detrimental to gas motion and may cause a disturbance, the performance of the RF plasma torch with the impeller disk is such that a ratio of tangential velocity to axial velocity is below 1 , indicating that gas motion without the disk may be more effective.

[0136] In an embodiment such as shown in Figures 1 to 8, the RF plasma torch 200 also includes the at least one conductive rod 215, which functions as the conductive element (like the at least one conductive element 215 of the RF plasma torch 200) for generating a high-voltage spark discharge. In an embodiment, the conductive rod 215 is housed at least partially within the insulated mounting tube 246 that extends from the torch head 216 into the torch body 212. The specific mounting arrangement of the conductive rod 215 can vary; it may be positioned independently within the torch housing 210 or, in some arrangements, it could potentially extend through the central shaft of the impeller unit 240.

[0137] In an additional embodiment, the RF plasma torch 240 includes an adjustment mechanism 260. The adjustment mechanism 260 is provided to control the position of the conductive rod 215 and may alter an axial position of the conductive rod 215 within the torch channel 218.

[0138] In an additional embodiment such as shown in Figure 1 to 8, the adjustment mechanism 260 includes a spring mechanism 222 that is structured to drive the conductive rod 215 back and forth through the insulated mounting tube 246 for varying the position of the conductive rod 215 within the torch channel 218. The spring mechanism 222 provides a controlled return force, ensuring the conductive rod 215 can retract after activation or can maintain a predetermined position within the torch channel 218. The spring's tension or compression can be pre-set or adjustable to control the force exerted on the rod, influencing its stability and responsiveness.

[0139] In an alternative embodiment, the adjustment mechanism 260 can include a stepper motor unit in place of the spring mechanism. The stepper motor unit can provide automated and precise mechanical control over the igniter rod's motion, allowing for fine-tuned and repeatable positioning. This stepper motor can be operatively connected to the conductive rod 215 to translate rotational motion into linear displacement of the conductive rod 215 within the torch channel, thereby precisely controlling the position of the rod.ExamplesThe following examples are presented to enable those skilled in the art to understand and to practice embodiments of the present disclosure. They should not be considered as a limitation on the scope of the disclosure, but merely as being illustrative and representative thereof.Example 1 - Torch Design Optimization

[0140] This example details an optimization process employed to determine the specific structural and dimensional parameters of the RF plasma torch 200 to achieve enhanced performance characteristics.

[0141] For the optimization process, the optiSLang software suite from Ansys was utilized. A Genetic Algorithm was selected as the optimization algorithm due to itseffectiveness in exploring complex design spaces. Parameter constraints for the optimization were set to +30 % from the initial parameter values, allowing for a significant but controlled exploration of the design space around an initial configuration.

[0142] For optimization of the performance of the RF plasma torch 200, two performance criteria were set as vortex quality and nozzle sizing. For the optimization, vortex quality was quantified as the number of complete gas revolutions (“turns”) inside the torch channel of the torch housing. As the gas is injected tangentially, its motion comprises both tangential (70) and axial (7a) velocity components optimal rotation requires> 1. For the simulations, nozzle sizing wasassessed for a converging nozzle at the outlet of the torch. A converging nozzle at the outlet can stabilize the vortex’s core diameter and prevent collapse near the apex. In the optimization process, the nozzle geometry was controlled by enforcing the ratio of inlet to outlet gas speeds of —s 1.6.Vout

[0143] The optimization was conducted over 200 iterations. A tournament selection method was employed for generating new design variations. The initial design of the RF plasma torch was used as the starting point for the optimization process.

[0144] Multiple objectives were defined for the optimization, aiming to balance various performance aspects of the plasma torch and to enhance the quality of the vortex flow. These objectives included: Objective 1 sought to maximize the average output pressure of the plasma jet. Objective 2 aimed to minimize the reverse vortex flow occurring before the impeller disk. Objective 3 was set to maintain the continuance ratio below a value of 1.2. Finally, Objective 4 sought to ensure the continuance ratio remains above a value of 0.9. Overall, these objectives were designed to balance pressure drop and turbulence intensity to maximize heat flux and plasma temperature by reducing electron-wall collision. By tailoring the shape ofthe torch body, particularly the apex (downflow) diameter, and adding a nozzle, the optimization aimed to enhance centrifugal forces, stabilize the spiral flow, and achieve a strong, high-efficiency plasma vortex. The proposed RF-ICP comprises various components, all of which were tested and assessed for their effectiveness in enhancing the quality of vortex flow. Consequently, different torch geometries with varying chamber diameters were simulated, and the ANSYS suite was used to optimize the size of each component of the torch based on the optimization process illustrated in Figure 10.

[0145] During the optimization process, numerous generations and iterations of the design were created and evaluated against these objectives. Consequently, a plurality of optimal or near-optimal solutions were generated. To select the most advantageous solution, all iteration input and output parameters were exported to a separate table for detailed evaluation and comparison.

[0146] The optimization yielded significant improvements in performance. For instance, the initial output value of the output pressure was measured at 0.013 Pa. Following the optimization process, at design iteration 174, the output pressure was increased by approximately 400 times, reaching 3.8 Pa.Example 2: Optimized Torch Body Geometry

[0147] This example details the optimized geometric relationships derived for the torch body, specifically the plasma discharge chamber length and the nozzle diameter.

[0148] The plasma discharge chamber length exhibits a specific relationship with the torch body diameter. As illustrated in Figure 11 (Variation of the torch body length with the torch body diameter), this relationship is substantially linear. The linear relation can be described by a function with constant values, specifically a=2.686 and b=14.71. Thus, the optimized relation between the torch body length (Ltorch) and the torch body diameter (Dtorch) is given by:

[0149] = 2.7, L = 2.7 D

[0150] Regarding the nozzle diameter, the optimized relationship between the torch body diameter (Dtorch) and the outlet diameter (Doutiet) can be described by the following relation:

[0151] DNozzel= 1O.3D0 056

[0152] where X and Y are empirically derived constants from the optimization.Example 3: Optimized Impeller Unit Dimensions

[0153] This example provides the optimized dimensions and configurations for the impeller unit, based on the optimization process described previously.

[0154] The impeller unit's central dimensions are fixed: the impeller hub diameter is 2.5 cm, and its height is 2.0 cm. The impeller unit is designed with 20 blades. The length of each blade is specifically related to the torch body diameter, as illustrated in Figure 12 (Dependency of blade length on torch body diameter). This relationship is linear, indicating that as the torch body diameter changes, the blade length scales proportionally: Lbiade= a + bD (a = -2.45833 and b = 0.364)

[0155] Each of these 20 blades is fixed to the impeller hub at a precise angle of 78.15° relative to the horizontal plane of the impeller. This specific blade angle and its relation to the torch body diameter are optimized to efficiently induce the desired reverse vortex flow.Example 4: Plasma Torch with Vortex Flow and Optimized Geometry

[0156] This example provides the details of a CFD-based analysis of key plasma parameters for the inductively-coupled plasma torch, using COMSOL Multiphysics software. The analysis demonstrated that modifications and optimization of key plasma parameters (i.e., the torch design including the nozzle, chamber volume, and gas entry angle) can increase the torch’s plasma energy efficiency by up to 90%.

[0157] Figure 13A and 13B illustrate how plasma temperature and heat flux outside the torch vary with different gas entry angles (cp) under a 5 standard liters per minute (SLPM) Argon (Ar) flow. A direct axial flow corresponds to <p = 0°, while increasing <p initiates a circulating gas pattern that further confines the plasma. Asshown in Figure 13C and 13D, the optimal performance for both temperature and heat flux was achieved at <p = 10°. The gas inlet angle into the torch body can be calculated using the following equation:

[0159] where r is the radial distance from the axis of symmetry, vzis axial velocity. In the equation, the optimal <p value is used to determine the position of the gas inlet tube that gives the maximum vortex flow pattern, which leads to the maximum centrifugal force that confines the plasma. This equation helps determine the optimal position for the gas inlet tube, which generates the maximum vortex flow pattern, leading to the highest centrifugal force for plasma confinement.

[0160] As shown in Figure 17C, the swirl number, which indicates the intensity of the vortex flow, increased with cp. This intensified swirl increased the probability of electron-electron and electron-atomic collisions, and electron-wall collisions, all of which influence plasma properties. Electron temperature, radiofrequency (RF) power, and gas flow rate are interconnected. The electron temperature typically decreases as RF power rises due to the increased impact of two-stage ionization and electron-electron interactions, which intensify at higher plasma densities. Similarly, increasing the gas flow rate raises the likelihood of electron-atom collisions, which increases plasma density and lowers electron temperature.

[0161] The effect of varying Ar flow rates is shown in Figures 14A and 14B, which illustrates how plasma temperature and total heat flux varied with distance from the torch at a fixed angle of <p = 10°. Figures 14C and 14D show these parameters at the optimal flow rate of 10 SLPM. Increasing the flow from 4 to 10 SLPM raised both plasma temperature and heat flux, while further increases caused plasma temperature and heat flux to decrease. This reduction can be attributed to the plasma volume expanding and interacting with the chamber walls. Therefore, the torchbody's geometry was considered and modified to enhance the centrifugal force from the vortex flow and improve plasma parameters.

[0162] Adding a nozzle to the plasma chamber outlet can significantly alter the plasma parameters. Figures 15A and 15B illustrate how a 1 cm long, 5 mm radius nozzle changed the spatial profiles of plasma temperature and total heat flux at a flow of 10 SLPM and cp = 10°. Figures 15C and 15D show the plasma parameters with the nozzle installed. While the plasma temperature remained unchanged, the heat flux increased significantly from 4-18 x 105W / m2

[0163] The effect of varying nozzle radii is shown in Figures 16A and 16B, which illustrate how plasma parameters changed with distance from the torch for different nozzle radii. Figures 16C and 16D illustrate these profiles at the optimal nozzle radius of 3 mm. Adding a nozzle stabilized the vortex position and size, preventing internal spirals from collapsing and maintaining a substantially constant flow. The apex diameter influenced the torch performance, as a larger diameter reduced pressure drop and turbulence, which, in turn, reduced heat flux and increased plasma temperature. After adding a nozzle, the gas inlet angle was re-examined, as the nozzle alters the internal velocity profile. As shown in Figure 17A and 17B, the optimal gas inlet angle changes to cp = 5° with a 3 mm nozzle radius, 10 SLPM gas flow rate, 10 mm torch body radius, and 770 W RF power.

[0164] A larger chamber diameter was shown to diminish the effects of wall cooling, a major source of energy loss. The studies performed within this example indicate that a larger chamber helps maintain higher electron temperatures and improves ionization efficiency, while smaller chambers lead to greater thermal losses. Figures 18A and 18B show how plasma parameters vary with distance for several chamber diameters. Increasing the chamber diameter from 10 to 16 mm increased both temperature and heat flux, while a further increase to 18 mm caused temperature and heat flux to decrease. Figures 18C and 18D show these properties for the optimal 16 mm chamber diameter.

[0165] Plasma stability, homogeneity, and energy absorption are all dependent on chamber diameter. A mismatch in diameter can lead to instability and reduced efficiency. The effect of RF power on plasma temperature and heat flux is illustrated in Figures 19A and 19. Increasing power raised electron energy and plasma density.

[0166] Table 1 summarizes the specifications for various gases (Ar, N2, O2), highlighting that the optimized torch design improves energy efficiency by up to 93% for argon. The heat flux of nitrogen and oxygen is higher than that of argon because their ionization temperatures are lower, leading to increased charge generation.Table 1 : Simulation setup parameters for different gas typesExample 5: RF-ICP Torch Geometry and Modeling Conditions

[0167] This example provides details of the RF-ICP torch geometry and modeling conditions for the simulations and results presented in Example 8.

[0168] Figures 20A and 20B illustrate the geometry of the RF-ICP torch, showing the configuration without a nozzle in Figure 20A and with a nozzle in Figure 20B. The geometry includes specific dimensions to facilitate the tangentially supplied gas flow. To model this, the boundary conditions at the bottom inlet are defined by a velocity field with axial (u_z), azimuthal (u_cp), and radial (u_r) components.

[0169] The operational parameters, as shown in Table 2, include an Ar gas temperature set to 500 K. This temperature facilitates plasma ignition at a low power of 770 W, a technique commonly used in experimental work. The temperature gradient at the wall boundary is also carefully managed to ensure computationalstability. Initially, a steep temperature gradient of 200 K existed between the wall (500 K) and the boundary (300 K), which could lead to instabilities in the nonlinear solver. By raising the wall temperature to 350 K, the gradient is smoothed to 150 K, which improves the convergence behavior of the simulation.

[0170] Table 2: Operational parameters for simulations

[0171] The modeling of the ICP torch, as outlined in this example, uses a set of simplifying assumptions to make the problem computationally efficient. The model is considered two-dimensional and axisymmetric, and gravitational effects are neglected due to their minimal influence. The supplied gas is assumed to be incompressible because of the low Mach numbers. The plasma is treated as optically thin and in local thermodynamic equilibrium (LTE), which allows for the use of simplified thermodynamic models. The flow is assumed to be steady and laminar, with a uniformly distributed swirling pattern formed by the tangential introduction of Argon gas. The computational mesh used for this model consists of 66,644 elements, as depicted in Figure 19C.

[0172] The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the above-described embodiments are intended to be examples of the present disclosure and alterations and modifications may be affected thereto, by those of skill in the art, without departing from the scope of the disclosure that is defined solely by the claims appended hereto.

Claims

What is claimed is:

1. A radio-frequency (RF), inductive plasma torch comprising: a torch housing that defines a torch channel therewithin and that includes at least one inlet for injecting at least one plasma forming gas into the torch channel, the at least one inlet being positioned at an inlet section of the torch housing; an induction coil that includes first and second ends that are operatively connected to an external RF power source for receiving an alternating RF current therefrom, the flow of the alternating RF current in the induction coil generating an alternating, magnetic field therefrom, within the torch channel; at least one conductive rod that is connected to the inlet section of the torch housing and that extends along a portion of the torch channel, the at least one conductive rod being operatively connected to an external voltage source for generating a high-voltage spark discharge therefrom, the high-voltage spark discharge and the alternating, high-gradient magnetic field collectively ionizing the at least one plasma forming gas for generating a flow of plasma within the torch channel; and an impeller unit that is rotatably mounted within the torch channel of the torch housing, proximate the inlet section of the torch housing, the impeller unit being sized and oriented relative to the torch channel such that when the impeller unit is driven to rotate within the torch channel, rotation of the turbine inducing a reverse vortex flow of the at least one plasma forming gas within the torch channel.

2. The radio-frequency, inductive plasma torch of claim 1 , wherein the torch housing further comprises at least one outlet for expelling the flow of plasma from the torch housing.

3. The radio-frequency, inductive plasma torch of claim 2, wherein the inlet section of the torch housing is defined at a first end of the torch housing; andwherein the at least one outlet is formed at a second end of the torch housing that is opposite the first end of the torch housing.

4. The radio-frequency, inductive plasma torch of claim 2 or 3, wherein the impeller unit further comprises an impeller head, the impeller head being positioned proximate the at least one inlet such that the at least one plasma forming gas is injected into the torch channel proximate the impeller head.

5. The radio-frequency, inductive plasma torch of claim 4, wherein the impeller head is a radial impeller head with a plurality of radial guide vanes.

6. The radio-frequency, inductive plasma torch of claim 4, wherein each radial guide vane of the plurality of radial guide vanes is oriented at an angle relative to a radial plane of the impeller head.

7. The radio-frequency, inductive plasma torch of claim 4, wherein each radial guide vane of the plurality of radial guide vanes has a negative blade angle such that a direction of thrust of the impeller head is oriented substantially towards the inlet section of the torch housing.

8. The radio-frequency, inductive plasma torch of claim 4, wherein the impeller unit further comprises an impeller shaft, the impeller shaft having a first end that is connected to the impeller head and a second end that extends towards the at least one outlet of the torch housing.

9. The radio-frequency, inductive plasma torch of claim 8, wherein the impeller unit further comprises an impeller disk, the impeller disk being connected to the second end of the impeller shaft such that the impeller disk is spaced apart from the impeller head.

10. The radio-frequency, inductive plasma torch of claim 9, wherein the impeller disk is oriented substantially perpendicular to a longitudinal axis of the torch channel; and wherein a ratio of a diameter of the impeller disk to a diameter of the torch channel is in a range from about 1 :8 to about 1 :2.11 . The radio-frequency, inductive plasma torch of claim 6 or 7, wherein impeller shaft is sized such that a ratio of a diameter of the impeller disk to a distance between the impeller head and the impeller disk is in a range from about 4:1 to about 1 :1.

12. The radio-frequency, inductive plasma torch of any one of claims 8 to 11 , wherein the impeller head is rotatably mounted within the torch channel such that a central, rotational axis of the impeller head is substantially colinear with a central, longitudinal axis of the torch channel, and a long axis of impeller shaft is substantially colinear with the central, rotational axis of the impeller head.

13. The radio-frequency, inductive plasma torch of claim 1 , further comprising: a dielectric sheath that is positioned within, and which extends along a length, of the torch channel; the induction coil being circumferentially disposed around a length of the dielectric sheath, and at least one conductive element extending along a portion of the torch channel within the dielectric sheath; wherein the at least one inlet is formed on a sidewall of the torch housing; and wherein the at least one inlet is oriented relative to the torch channel such that the at least one plasma forming gas is injected along an inner surface of the dielectric sheath for producing a vortex flow of the at least one plasma forming gas within the dielectric sheath.

14. The radio-frequency, inductive plasma torch of claim 13, wherein the torch channel has a substantially cylindrical form, wherein each the dielectric sheath has asubstantially tubular form, and wherein the torch channel and dielectric sheath are substantially concentric.

15. The radio-frequency, inductive plasma torch of claim 3, wherein the torch housing further comprises a tapered, conical section that is formed proximate the second end of the torch housing; and wherein the at least one outlet is defined on the tapered, conical section of the torch housing.

16. The radio-frequency, inductive plasma torch of claim 1 , wherein the induction coil further includes a through channel extending along the length thereof, and wherein the through channel includes an inlet formed on the first coil end and an outlet formed on the second coil end for circulating at least one induction coil cooling fluid along the through channel.

17. The radio-frequency, inductive plasma torch of claim 13, wherein the dielectric sheath extends to a predetermined longitudinal position along the torch channel, wherein the induction coil is circumferentially disposed about the dielectric sheath such that the induction coil extends from a first longitudinal position to a second longitudinal position along the torch channel, the second longitudinal position being defined between the first longitudinal position and the predetermined longitudinal position; and wherein the at least on conductive rod extends to a location between the first longitudinal position and the second longitudinal position.

18. The radio-frequency, inductive plasma torch of claim 1 , wherein the torch housing further includes at least one radio-frequency shielding layer for blocking the emission of radio-frequency radiation that is generated within the torch channel.

19. The radio-frequency, inductive plasma torch of claim 13, further comprising at least one injector rod that is mounted within the dielectric sheath and that extends fromthe inlet section of the torch housing, wherein the at least one injector rod includes a conduit extending along the length thereof; and wherein the conduit is in fluid communication with a source of reaction fluid for injection the reaction fluid into the torch channel via the at least one injector rod.

20. A radio-frequency, inductive plasma torch comprising: a torch housing that defines a torch channel therewithin and that includes at least one inlet for injecting at least one plasma forming gas into the torch channel, the at least one inlet being positioned at an inlet section of the torch housing; a dielectric sheath that is positioned within, and which extends along a length, of the torch channel; an induction coil that is circumferentially disposed around a length of the dielectric sheath, the induction coil including first and second ends that are operatively connected to an external RF power source for receiving an alternating RF current therefrom, the flow of the alternating RF current in the induction coil generating an alternating, magnetic field therefrom, within the torch channel; first and second igniter pins that are mounted in the torch channel and that extend along a length of the inner dielectric sheath, the first and second igniter pins being operatively connected to an external voltage source for generating a high-voltage spark discharge therebetween, the high-voltage spark discharge and the alternating, magnetic field collectively ionizing the at least one plasma forming gas for generating a flow of plasma within the torch channel; and an impeller unit that is rotatably mounted within the torch channel of the torch housing, proximate the inlet section of the torch housing, the impeller unit being sized and oriented relative to the torch channel such that when the impeller unit is driven to rotate within the torch channel, the rotation of the turbine induces a reverse vortex flow of the at least one plasma forming gas within the torch channel.

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