Systems and methods for thermionic energy conversion

Abstract

A system for generating thermionic energy preferably includes one or more thermionic energy converters and optionally includes one or more power inputs, airflow modules, and / or electrical loads. A thermionic energy converter preferably includes an emitter module, a collector module, and / or a seal, and optionally includes spacers. The thermionic energy converter preferably defines a chamber and / or a heating chamber. A method for generating thermionic energy preferably includes receiving power, emitting electrons, and / or receiving emitted electrons, and optionally includes convective heat transfer.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Application Serial No. 62 / 756,502, filed November 6, 2018, and U.S. Provisional Application Serial No. 62 / 915,160, filed October 15, 2019, each of which is incorporated herein by reference in its entirety.

[0003] Government Support Statement

[0004] This invention was made with government support under contracts W911NF-17-P-0034 and W911NF-18-C-0057 granted by the Defense Advanced Research Projects Agency (DARPA). The government holds certain rights to this invention. Technical Field

[0005] This invention relates generally to the field of thermionic energy conversion, and more specifically to new and useful systems and methods for thermionic energy conversion.

[0006] background

[0007] Typical thermionic energy converters (TECs) suffer from limited power conversion efficiency, especially when considering the efficiency losses associated with transferring heat to the TEC. Therefore, there is a need to create new and useful systems and methods for thermionic energy conversion in the field of thermionic energy conversion. Brief description of the attached diagram

[0009] Figure 1A This is a schematic representation of an embodiment of a system for generating thermionic energy.

[0010] Figure 1B It is a schematic representation of a variant of the system.

[0011] Figures 2A-2C These are cross-sectional views of the first, second, and third specific examples of the system, respectively.

[0012] Figure 3A This is a schematic representation of a cross-sectional view of an example of the TEC of the system.

[0013] Figure 3B yes Figure 3A A detailed view of a specific example of a part of TEC.

[0014] Figure 3C This is a schematic representation of a cross-sectional view of the second example of the TEC of the system.

[0015] Figure 3D yes Figure 3C A detailed view of a specific example of a part of TEC.

[0016] Figure 4 This is an exploded cross-sectional view of the first specific example of TEC.

[0017] Figure 5 This is a cross-sectional view of a second specific example of TEC.

[0018] Figure 6A This is a radial section view of an axisymmetric example of TEC.

[0019] Figure 6B yes Figure 6A A radial section diagram of a specific example of a TEC.

[0020] Figure 7 It is a schematic representation of a method for generating thermionic energy.

[0021] Description of preferred embodiments

[0022] The following description of preferred embodiments of the invention is not intended to limit the invention to these preferred embodiments, but rather to enable any person skilled in the art to practice and use the invention. 1. System.

[0023] The system 10 for generating thermionic energy preferably includes one or more thermionic energy converters 11 (TECs). The system may optionally include one or more power inputs 12, airflow modules 13, and / or electrical power loads 14 (e.g., such as...). Figure 1A , Figure 1B , Figure 2A and / or Figure 2B (As shown). However, the system may additionally or alternatively include any other suitable components.

[0024] 1.1 Thermo-ion energy converter.

[0025] The thermionic energy converter 11 (TEC) is preferably used to convert heat input into electrical power output. The TEC preferably includes an emitter module 100, a collector module 200, and a seal 300 (e.g., as shown in the image). Figures 3A-3B (As shown). The TEC may optionally include spacer 400. However, the TEC may additionally or alternatively include any other suitable element.

[0026] The TEC preferably defines a chamber 500. The chamber is preferably defined by the inner walls of the emitter module, collector module, and / or seals (e.g., where the inner walls define the boundaries of the chamber). The chamber is preferably fluidly isolated from the surrounding environment (e.g., the atmosphere) of the TEC. Preferably, the chamber environment is at a reduced pressure compared to the surrounding environment (e.g., a complete or partial vacuum). The chamber may contain one or more substances (e.g., barium, cesium, oxygen, sodium, strontium, zirconium, etc.). However, the chamber may additionally or alternatively have any other suitable properties.

[0027] The TEC preferably defines a heating cavity 600. The heating cavity is preferably defined by a portion of the wall of the emitter module (e.g., the outer wall of the inner shell). The heating cavity is preferably open to the surrounding environment (e.g., open at one end), but may alternatively be a closed cavity and / or any other suitable cavity. However, the heating cavity may additionally or alternatively have any other suitable properties.

[0028] The TEC may optionally include one or more elements, such as those described in U.S. Patent Application 15 / 969,027, filed May 2, 2018, entitled “SYSTEM AND METHOD FOR WORK FUNCTION REDUCTION AND THERMIONIC ENERGY CONVERSION” and / or U.S. Patent Application 16 / 044,215, filed July 24, 2018, entitled “SMALL GAPDEVICE SYSTEM AND METHOD OF FABRICATION”, each of which is incorporated herein by reference in its entirety. For example, the emitter module may include “cathode 200” (or elements thereof) as described in U.S. Patent Application 15 / 969,027, the collector module may include “anode 100” (or elements thereof) as described in U.S. Patent Application 15 / 969,027, and / or the spacer may include “spacer 120” (or elements thereof) as described in U.S. Patent Application 16 / 044,215.

[0029] However, TEC may additionally or alternatively include any other suitable elements arranged in any suitable manner.

[0030] 1.1.1 Transmitter module.

[0031] The transmitter module 100 is preferably used for receiving heat (e.g., from a power input) and emitting electrons (e.g., into a chamber). The transmitter module preferably includes one or more electron emitters 110, an inner housing 120, and / or an outer housing 130 (which may additionally or alternatively be part of the collector module and / or a separate element of the TEC), such as via... Figure 3A , Figure 3B and / or Figure 4 - As shown in the example in Figure 6. The transmitter module may optionally include one or more electrical leads 140 and / or radiation shielding 150. However, the transmitter module may additionally or alternatively include any other suitable elements.

[0032] The electron emitter (i.e., the cathode) preferably contains (e.g., is, is substantially composed of, etc.) one or more metals, preferably refractory metals such as tungsten, tantalum, rhenium, ruthenium, molybdenum, nickel, chromium, one or more superalloys (e.g., Inconel, Hastelloy, Kanthal, etc.), niobium, platinum, rhodium, iridium, etc. However, the electron emitter may additionally or alternatively include one or more semiconductor materials, insulating materials, and / or any other suitable materials. The electron emitter may be a deposited layer (e.g., deposited by chemical vapor deposition, physical vapor deposition, jet deposition, electrodeposition, etc.), may be a bulk material, and / or may be manufactured in any other suitable manner.

[0033] The electron emitter preferably coats the interior of a portion of the inner housing (e.g., the inner wall, such as the wall closest to the chamber), more preferably, wherein the electron emitter is arranged across the chamber facing the electron collector (e.g., wherein the electron emitter coats the portion of the inner housing that crosses the chamber facing the electron collector). This portion is preferably part of and / or close to the flame receiving area of ​​the inner housing, and preferably intersects and / or is centered along a central axis (e.g., a central axis defined by the emitter module, such as the central axis of the heating chamber). However, the electron emitter may be additionally or alternatively arranged in any other suitable location.

[0034] The electron transmitter is preferably conductively connected to other elements of the transmitter module, such as connections to the inner housing (e.g., to a conductive layer of the inner housing), the outer housing (e.g., via the inner housing), and / or transmitter leads (e.g., preferably via the outer housing, alternatively via the inner housing and / or any other suitable element). However, the electron transmitter may additionally or alternatively be conductively connected (and / or otherwise electrically coupled) to any other suitable element of the transmitter module and / or the system.

[0035] The electron emitter is preferably thermally coupled to the inner housing, more preferably to the flame receiving region of the inner housing (e.g., where the electron emitter is heated by the inner housing). However, the electron emitter may additionally or alternatively be thermally coupled to any other suitable element of the system.

[0036] An electron transmitter preferably includes a substantially flat surface (e.g., a surface that defines a transmitter plane) that preferably defines a chamber, but the electron transmitter may additionally or alternatively include any other suitable surface.

[0037] However, the electron transmitter may additionally or alternatively have any other suitable properties.

[0038] The inner shell of the transmitter module preferably comprises a multi-layered structure. For example, the inner shell may include a fire-resistant layer (FPL), a conductive layer, and / or a sandwich structure (e.g., such as...). Figure 3B and / or Figure 5 (As shown). However, the inner shell may additionally or alternatively include any other suitable layers and / or other elements. The interfaces between the layers of the inner shell may be smooth, rough, graded, interdiffused, and / or have any other suitable properties. In some embodiments, the layers (or subsets thereof) of the inner shell do not define discontinuous interfaces, but rather vary substantially smoothly in composition from one layer to the next. The inner shell preferably has a total thickness ranging from 0.05 to 10 mm, preferably 0.2 to 4 mm (e.g., 0.2 to 0.5 mm, 0.5 to 2 mm, 2 to 4 mm, 0.5 to 1 mm, or 1 to 2 mm, etc.).

[0039] The flame field (FPL) is preferably used to protect other components of the inner housing (and / or other components of the transmitter module, such as the electron transmitter) from the flame in the heating chamber. The FPL is preferably positioned near the end of the heating chamber (e.g., defining the heating chamber). The FPL may include (e.g., it is made of, or is primarily composed of, alumina, silica, boron trioxide, mullite, platinum, rhodium, iridium, silicon, silicides (such as molybdenum disilicide, silicon carbide, silicon nitride), Hitemco R512E, stainless steel, nickel, chromium, one or more superalloys (e.g., chromium-nickel-iron alloy, Hastelloy, Contac, etc.) and / or any other suitable material. In some examples, FPL has a thickness in the range of 0.0005-10 mm (e.g., 0.0005-0.002 mm, 0.002-0.005 mm, 0.005-0.01 mm, 0.01-0.02 mm, 0.02-0.05 mm, 0.05-0.2 mm, 0.2-3 mm, 3-10 mm, 0.02-0.1 mm, 0.1-0.3 mm, 0.3-0.5 mm, 0.5-1 mm, 1-2 mm, and / or 2-5 mm, etc.). However, FPL may additionally or alternatively have any other suitable properties.

[0040] The conductive layer is preferably disposed near the proximal end of the chamber (e.g., defining the chamber) (e.g., the conductive layer is opposite the heating chamber across the FPL). The conductive layer is preferably conductive. The conductive layer may be adjacent to the electron emitter (e.g., the conductive layer may be part of a layer of the same material as the electron emitter, where the conductive layer and the electron emitter together form a monolayer, such as a single metal layer). The conductive layer is preferably used to electrically connect the electron emitter to one or more other elements of the emitter module, such as the housing. In some examples, the conductive layer has one or more properties that are substantially similar to those of the FPL (and / or similar to those of possible embodiments of the FPL described above), such as having substantially the same composition and / or thickness as the FPL. However, the conductive layer may additionally or alternatively have any other suitable properties.

[0041] The inner shell may optionally include a sandwich layer (or multiple sandwich layers). The sandwich layer may serve as a diffusion barrier layer (e.g., reducing diffusion between the FPL and the conductive layer and / or between any other suitable layers or regions of the inner shell), an adhesive layer (e.g., adhering to other layers of the inner shell (such as the FPL and / or conductive layers, etc.) and / or improving adhesion between other layers of the inner shell). The sandwich layer may include (e.g., made of, primarily composed of, etc.) alumina, silica, boron trioxide, titanium oxide, mullite, silicon, silicides (such as molybdenum disilicide, silicon carbide, silicon nitride), zirconium diboride, graphite, carbon composites and / or other carbon-containing materials (e.g., carburizing materials), niobium carbide, hafnium carbide, tantalum carbide, zirconium carbide, tantalum nitride, aluminum nitride, titanium nitride, nickel, one or more superalloys and / or any other suitable material. In the example, the interlayer thickness can be in the range of 0.0005-10 mm (e.g., 0.0005-0.001 mm, 0.001-0.002 mm, 0.002-0.005 mm, 0.005-0.02 mm, 0.02-0.5 mm, 0.5-2 mm, 0.02-0.05 mm, 0.05-0.1 mm, 0.1-0.2 mm, 0.2-0.5 mm, 0.5-1 mm, 1-2 mm, 2-5 mm, or 5-10 mm, etc.), but can additionally or alternatively be thicker, thinner, and / or have any other suitable dimensions. However, the interlayer can additionally or alternatively have any other suitable properties.

[0042] The inner shell preferably comprises a planar (or substantially planar) portion and / or one or more sidewalls (e.g., such as...). Figure 3A and / or Figure 4(As shown). The planar portion is preferably substantially parallel to the emitter plane (e.g., where the electron emitter is attached and / or deposited on the planar portion), but alternatively may have any other suitable arrangement. The sidewalls are preferably straight sidewalls. The sidewalls are preferably arranged opposite the planar portion of the inner shell to the emitter plane across the inner shell (and / or opposite the electron collector across the chamber and / or across the electron emitter). The sidewalls preferably extend from a first inner shell sidewall end near the planar portion to a second inner shell sidewall end. The sidewalls may extend substantially perpendicular to the planar portion and / or the emitter plane, at an angle to the planar portion and / or the emitter plane (e.g., within a threshold angle of the vertical, such as within 1°, 2°, 3°, 5°, 10°, 15°, 20°, 25°, or 30° of the vertical), and / or in any other suitable direction. In some embodiments, the inner shell includes one or more bridging features, such as chamfers and / or bevels, at and / or near the first inner shell sidewall end (e.g., between the sidewall and the planar portion). The sidewalls preferably define a reference axis, such as a longitudinal axis (e.g., substantially perpendicular to the planar portion and / or the emitter plane, intersecting the electron emitter and / or electron collector, etc.), with the sidewalls substantially centered on this longitudinal axis (e.g., wherein the sidewalls are rotationally symmetric about the longitudinal axis, such as having 2x, 3x, 4x, 6x, or 8x rotational symmetry about the longitudinal axis, higher-order rotational symmetry about the longitudinal axis, circular symmetry about the longitudinal axis, etc.). However, the sidewalls may additionally or alternatively have any other suitable properties.

[0043] In one example, the inner shell includes a planar portion defining a substantially circular region (e.g., centered on the electron emitter). In a first specific example (e.g., where the sidewall extends substantially perpendicular to the planar portion and / or the emitter plane), the inner shell includes a single sidewall defining a cylindrical shell, wherein the cylindrical shell defines a cylindrical axis that preferably intersects and / or is substantially perpendicular to the electron emitter and electron collector. In a second specific example (e.g., where the sidewall extends obliquely to the planar portion and / or the emitter plane), the inner shell includes a single sidewall defining a conical or truncated conical shell (e.g., a truncated portion of a conical shell (preferably a perfect conical shell), terminating at the planar portion, the emitter plane, or a reference plane substantially parallel to the planar portion and / or the emitter plane), wherein the cylindrical shell defines a cylindrical axis that preferably intersects and / or is substantially perpendicular to the electron emitter and electron collector.

[0044] In some examples, the inner shell may have a length of 45-250 mm (e.g., 45-70 mm, 55-65 mm, 70-100 mm, 100-140 mm, 140-190 mm, or 190-250 mm), 20-45 mm, or 250-750 mm (e.g., sidewall length). In some examples, the inner shell may have a width of 10-30 mm (e.g., 10-15 mm, 15-20 mm, 18-22 mm, 20-25 mm, or 25-30 mm), 5-10 mm, or 30-60 mm (e.g., width of the planar portion, such as the diameter of the planar portion). However, the inner shell may have any other suitable shape and / or size.

[0045] The inner shell preferably includes one or more heat receiving regions (e.g., flame receiving regions) that are preferably used to receive flames within the heating chamber (e.g., flames incident on the flame receiving regions). The flame receiving regions are preferably part of the FPL (and optionally part of any other suitable element of the interlayer and / or inner shell). Although referred to herein as flame receiving regions, those skilled in the art will recognize that the inner shell may additionally or alternatively include one or more heat receiving regions configured to receive heat (e.g., heat from the burner and / or other power outputs) in any suitable manner (e.g., by radiation, convection, and / or conduction), and the heat receiving regions may include elements such as those described herein with respect to flame receiving regions and / or have properties such as those described herein with respect to flame receiving regions, but may additionally or alternatively include any other suitable elements and / or have any other suitable properties.

[0046] The flame receiving region is preferably arranged between the electron emitter and the flame (e.g., between the electron emitter and the heating chamber). The electron emitter (and optionally some or all of the inner shell conductive layers) is preferably arranged between the flame receiving region and the chamber, and / or preferably attached to the flame receiving region (wherein one is formed by deposition onto the other). In some embodiments, the flame receiving region may include one or more heat sinks and / or other heat transfer structures that can be used to increase heat transfer (e.g., heat transfer from the flame to the flame receiving region). However, the flame receiving region may additionally or alternatively include any other suitable elements arranged in any suitable manner.

[0047] One or more surfaces of the inner shell may be ground, polished, and / or buffed (e.g., electropolished) and / or otherwise smoothed, which can be used to reduce thermal radiation from the surfaces. The surfaces may additionally or alternatively be coated with one or more layers (e.g., thin layers) of a low-emissivity material, which can also be used to reduce thermal radiation. This can reduce heat loss (e.g., heat loss from the electron emitter, flame receiving area, and / or other inner shell components) and / or reduce heat transfer to other components (e.g., to the outer shell, electron collector, and / or other collector module components).

[0048] However, the inner shell may additionally or alternatively include any other suitable elements arranged in any suitable manner.

[0049] The outer casing is preferably used for electrical connection to the inner casing and for mechanically and / or thermally coupling (e.g., connecting) the inner casing to the collector module. The outer casing preferably exhibits high thermal conductivity and / or oxidation resistance (e.g., at high temperatures, such as in the range of 100-900°C, preferably 300-600°C).

[0050] The outer shell preferably surrounds or substantially surrounds the inner shell (e.g., where the outer shell, together with the inner shell it surrounds, defines a portion of the chamber). The inner and outer shells may define a gap of substantially constant width (e.g., a gap between the inner walls of the inner and outer shells), a gap with varying widths (e.g., the gap gradually tapers from a wider gap at or near a first end to a narrower gap at or near a second end, or no gap), and / or have any other suitable properties. For example, the outer shell may define a second cylindrical shell, which is preferably concentric with the cylindrical sidewalls of the inner shell and has a larger radius than the cylindrical sidewalls of the inner shell. However, the outer shell may alternatively define any other suitable shape. The outer shell preferably has dimensions similar to the inner shell, such as having a substantially equal length and a slightly larger width than the inner shell (e.g., where the width difference defines the gap width). The gap is preferably large enough to avoid thermal (and / or electrical) short circuits between the inner and outer shells (e.g., due to sidewall roughness; due to materials associated with low work function coatings, such as droplets of Cs metal, etc.). In some examples, the gap (e.g., average gap, minimum gap, etc.) is larger than a threshold width (e.g., 0.01 mm, 0.03 mm, 0.1 mm, 0.2 mm, 0.5 mm, or 1 mm, etc.), but may additionally or alternatively be less than 0.01 mm or have any other suitable width. For example, the gap may have a width in the range of 0.2-20 mm (e.g., 1-10 mm, 1-3 mm, 3-6 mm, 5-10 mm, or 10-20 mm, etc.), but may additionally or alternatively be narrower (and / or have no or substantially no gap, such as where the gap decreases to zero at or near the second end, thus bridging the inner and outer shells) and / or wider. However, the gap width may additionally or alternatively be in the range of 20-50 mm, 50-200 mm, or greater than 200 mm. In some examples, the TEC includes one or more spacers, preferably thermally and / or electrically insulating spacers (e.g., insulating spheres, such as sapphire spheres), arranged within a cavity between the inner shell sidewall and the outer shell sidewall, which can be used to maintain a desired minimum gap width. The outer shell preferably defines a first end and a second end, more preferably corresponding to the first end and the second end of the inner shell (e.g., where the first end of the outer shell is close to the first end of the inner shell (e.g., substantially opposite each other across the cavity), the second end of the outer shell is close to the second end of the inner shell (e.g., substantially opposite each other across the cavity), and / or the direction from the first end of the outer shell to the second end of the outer shell is substantially aligned with the direction from the first end of the inner shell to the second end of the inner shell (e.g., where “substantially aligned” means that the angle between the vectors is less than a threshold amount (e.g., 1°, 2°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 45°, 60°, 75°, or 90°); the dot product between the vectors is positive; etc.).However, the casing can alternatively have any other suitable shape and / or size.

[0051] The housing preferably includes one or more thermally and / or electrically conductive elements (e.g., extending along the length of the housing, such as from a first end to a second end). In a first embodiment, the housing includes substantially uniform walls (e.g., metallic walls). In examples, the walls may include (e.g., made of one or more of the following, composed primarily of one or more of the following, etc.): nickel and / or nickel alloys (e.g., Monel, Kovar, Invar, Innovco, Alloy 42) (such as FeNi42, NILO 42, Glass Seal 42 and / or Pernifer). Materials include, but are not limited to, copper, stainless steel, titanium, and / or Hastelloy. The wall may optionally include one or more cladding layers (e.g., if the conductive wall material is not sufficiently oxidation-resistant, such as for copper or aluminum conductive wall materials). The cladding layers may include oxidation-resistant layers (e.g., nickel, nickel alloys, chromium, stainless steel, etc.) and / or interlayers that can act as diffusion-blocking layers between the conductive wall material and the oxidation-resistant layers. The interlayer is preferably disposed within the wall (e.g., the conductive wall material) and between the oxidation-resistant cladding layers. In one example, the interlayer includes cobalt. However, the interlayer may additionally or alternatively include any other suitable material.

[0052] In a first example of this embodiment, the wall comprises a copper core, a cobalt interlayer, and a nickel (or nickel alloy) anti-oxidation cladding. In a second example, the wall comprises an aluminum core and a stainless steel anti-oxidation cladding. However, the wall may additionally or alternatively include any other suitable elements and / or materials arranged in any suitable manner.

[0053] In a second embodiment, the housing includes one or more heat pipes (e.g., extending between a first end and a second end) that can be used to carry heat along the length of the housing. The heat pipes preferably comprise a solid enclosed fluid, which can transfer heat via convection. In examples, the body may include one or more of the materials described with respect to the first embodiment (e.g., stainless steel, Monel alloy, Hastelloy, etc.) and / or include any other suitable materials. In such examples, the fluid (e.g., a liquid and / or vapor at the housing temperature) may include tin, lead, sodium, cesium, potassium, and / or any other suitable material. However, the housing may additionally or alternatively include any other suitable structures configured to carry heat and / or may alternatively omit such structures.

[0054] The inner and / or outer shell may optionally define the launcher bridge. The launcher bridge preferably connects the inner and outer shells (e.g., at or near a second end of each shell). The launcher bridge preferably mechanically, electrically, and thermally connects the inner and outer shells (but alternatively, only a subset of these functions may be performed). The launcher bridge is preferably made of the same material (or a subset of these materials) as the inner or outer shell, but may additionally or alternatively include materials different from the inner and outer shells. In some examples (e.g., such as...), Figures 3A-3B and / or Figure 4 As shown, the launcher bridge includes a curved member extending from the inner shell and outer shell (e.g., substantially parallel to the inner shell and outer shell) and defining an arc bridging between the inner shell and outer shell. In other examples, the launcher bridge includes a substantially flat (e.g., planar) member extending between the inner shell and outer shell (e.g., substantially perpendicular to the inner shell and / or outer shell). However, the launcher bridge may additionally or alternatively define any other suitable structure.

[0055] The transmitter module may optionally include one or more transmitter leads. The transmitter leads are used to conduct electrical energy from the transmitter module to an external load. The transmitter leads are preferably conductive (e.g., made of metal). In the example, the transmitter leads may be (or include) wires, cables, and / or any other suitable conductive structure. The transmitter leads are preferably electrically coupled (e.g., conductively connected) to the electron transmitter. The transmitter leads are preferably connected (e.g., electrically and / or mechanically connected) to the housing, more preferably at or near the second end. However, the transmitter leads may additionally or alternatively be connected to any other suitable element of the transmitter module (e.g., connected to any conductive element electrically connected to the electron transmitter). However, the transmitter lead may additionally or alternatively have any other suitable properties.

[0056] The electron transmitter may optionally include one or more radiation shields. Radiation shields are used to reduce thermal radiation transmitted from the inner casing to the outer casing (and / or between any other suitable components of the system). The radiation shields are preferably made of refractory materials and preferably have low emissivity. In examples, the radiation shields may include (e.g., made of, primarily composed of, etc.) tungsten, tantalum, molybdenum, rhenium, nickel and / or nickel alloys (e.g., nickel alloys as described above), stainless steel, any other suitable superalloys and / or any other suitable materials.

[0057] The radiation shield is preferably arranged within the cavity, more preferably between the inner and outer shells. For example, the radiation shield may define one or more intermediate cylindrical shells between the inner and outer shells. The radiation shield preferably intersects with a large portion of the line of sight between the inner and outer shells (e.g., a large portion of the path that emitted radiation from the inner shell might otherwise have taken to reach the outer shell). For example, the radiation shield may intersect with such a path exceeding a threshold fraction (e.g., exceeding 99%, 98%, 95%, 90%, 85%, 75%, 60%, 50%, 40%, 30%, 20%, or 10%, etc.). In some embodiments, the radiation shield includes one or more spacers (e.g., electrically and / or thermally insulating spacers, such as spacers comprising alumina, MgO, BeO, and / or ZrO, etc.) arranged between the shield and other elements of the TEC (e.g., emitter modules (such as the inner and / or outer shells), collector modules, etc.) and / or (e.g., in embodiments including multiple radiation shields) between the radiation shields.

[0058] The radiation shield is preferably mechanically connected to the transmitter module at or near the transmitter bridge and / or at a location where the temperature (e.g., steady-state operating temperature) is similar to the radiation shield temperature (e.g., to reduce and / or minimize conductive heat flow between the radiation shield and the transmitter module), but may additionally or alternatively be connected to any other suitable location. The radiation shield may additionally or alternatively be part of the collector module and / or any other suitable element of the TEC (e.g., any other suitable element connected to the collector module and / or the TEC).

[0059] In some embodiments, the TEC is designed to achieve exceptionally long emitter lead lengths (e.g., compared to a typical TEC, compared to a TEC defining a heating cavity, etc.), which can achieve higher device efficiency. For example, this lead length can be achieved by extending the emitter module (e.g., a portion of the emitter module defining the heating cavity wall, such as an inner shell) to the opening of the heating cavity, and then extending a portion of the emitter module (e.g., a portion outside the heating cavity, such as a housing) away from the heating cavity opening. The housing preferably extends a distance comparable to the inner shell (e.g., more than 10%, 25%, 50%, 75%, 90%, 100%, or 110% of the inner shell length), thereby achieving significantly greater lead lengths for TECs whose emitter modules terminate at or near the heating cavity opening or terminate within the heating cavity.

[0060] However, the transmitter module may additionally or alternatively include any other suitable elements arranged in any suitable manner.

[0061] 1.1.2 Collector module.

[0062] Collector module 200 is preferably used to collect emitted electrons. Collector module preferably includes one or more electron collectors 210 (i.e., anodes), collector bridges 220, and / or cooling elements 230 (e.g., such as...). Figure 3A (As shown). The collector module may optionally include one or more collector leads 240 and / or collector contacts 250. However, the collector module may additionally or alternatively include any other suitable elements.

[0063] The electron collector is preferably a material having a low work function (e.g., in the operating environment of a TEC, such as at high temperatures and / or in an environment with a work function reducing material (such as barium, strontium, or cesium vapor, optionally also oxygen)), more preferably a work function lower than that of the electron emitter. In examples, the electron collector work function may be less than a threshold, such as 0.5–2.5 eV (e.g., 0.5–0.75 eV, 0.75–1 eV, 1–1.2 eV, 1.2–1.5 eV, 1.5–2 eV, or 2–2.5 eV, etc.). However, the electron collector may alternatively have any other suitable work function and / or other properties.

[0064] In a first embodiment, the electron collector includes one or more metals (e.g., comprising one or more metals, made of one or more metals, substantially composed of one or more metals, etc.), preferably refractory and / or low work function metals, such as tungsten, molybdenum, platinum, nickel, nickel alloys, superalloys, stainless steel, niobium, iridium and / or tantalum (e.g., metals that exhibit low work function themselves, and metals that exhibit low work function when exposed to a work function reducing environment (such as in barium, strontium and / or cesium environments, optionally including oxygen, etc.).

[0065] In a second embodiment, the electron collector comprises one or more semiconductors, more preferably n-type semiconductors (e.g., as described in U.S. Patent Application 15 / 969,027, filed May 2, 2018, entitled “SYSTEM AND METHOD FOR WORK FUNCTIONREDUCTION AND THERMIONIC ENERGY CONVERSION,” which is incorporated herein by reference in its entirety). The semiconductor is preferably a high-quality (e.g., single-crystal, low-impurity, etc.) semiconductor, but may additionally or alternatively include any semiconductor material of suitable quality. The semiconductor preferably comprises (e.g., is, is primarily composed of, etc.) Si (e.g., single-crystal, polycrystalline, and / or microcrystalline, amorphous, etc.), gallium arsenide (e.g., GaAs), aluminum gallium arsenide (e.g., Al), etc. x Ga 1-x As), gallium indium phosphide (e.g., Ga) x In1- x P) and / or aluminum gallium indium phosphide (e.g., Al) x Ga y In 1-x-y The term semiconductor (P) may be used herein to exclude materials such as transparent conductive oxides, but may additionally or alternatively include any suitable semiconductor material (e.g., as described in more detail below). Those skilled in the art will recognize that the term semiconductor as used herein preferably does not include materials such as transparent conductive oxides, but may alternatively include such materials. The semiconductor is preferably highly doped (e.g., greater than a threshold level such as 10⁻⁶). 15 / cm 3 10 16 / cm 3 10 17 / cm 3 10 18 / cm 3 10 19 / cm 3 10 20 / cm 3 The equilibrium charge carrier density (etc.); ranging from 10 15 / cm 3 -10 16 / cm 3 The range is 10 16 / cm 3 -10 17 / cm 3 The range is 10 17 / cm 3 -10 18 / cm 3 The range is 10 18 / cm 3 -10 20 / cm 3 The equilibrium carrier density is preferably high-doped but not degenerate-doped, but may additionally or alternatively include lower doping (e.g., equilibrium carrier density less than 10). 15 / cm 3 Less than 10 14 / cm 3 Less than 10 12 / cm 3 In 10 14 / cm 3 -10 15 / cm 3 Within the range, in 10 12 / cm 3 -10 14 / cm 3Within the range of 10, this may be desirable, for example, to reduce free carrier absorption and / or any other suitable doping level. In a specific example, the bulk semiconductor has a doping level in the range of 10. 16 / cm 3 -3×10 17 / cm 3 (For example, 1-3×10) 16 / cm 3 3-6×10 16 / cm 3 6-10×10 16 / cm 3 1-3×10 17 / cm 3 7.5×10 16 / cm 3 -2×10 17 / cm 3 The semiconductor preferably has substantially uniform doping, but may additionally or alternatively include doping variations (e.g., lateral and / or depth-dependent variations), such as gradients, discontinuities, and / or any other suitable doping characteristics. The semiconductor is preferably n-type silicon, but may additionally or alternatively include n-type silicon carbide, n-type germanium, n-type III-V semiconductors, and / or any other suitable materials. In some examples of this embodiment, the electron collector includes one or more additional layers (e.g., on or near the semiconductor), such as those described in U.S. Patent Application 15 / 969,027, filed May 2, 2018, entitled “SYSTEM AND METHOD FOR WORK FUNCTION REDUCTION AND THERMIONIC ENERGY CONVERSION,” which is incorporated herein by reference in its entirety.

[0066] The electron collector preferably has an alkali metal and / or alkaline earth metal coating (and / or its oxide), which can be used to reduce the collector work function. However, the electron collector may additionally or alternatively include any other suitable elements.

[0067] The electron collector is preferably conductively connected to other elements of the collector module, such as collector bridges and / or collector leads (e.g., where the electron collector is conductively connected to the collector leads via collector bridges and / or collector contacts). The electron collector is preferably thermally coupled to a cooling element (e.g., where heat is transferred from the electron collector to the cooling element, thereby cooling the electron collector), such as directly connected to the cooling element, thermally coupled to the cooling element via collector contacts and / or other elements of the collector module, and / or otherwise thermally coupled to the cooling element. The electron collector is preferably mechanically coupled (e.g., mechanically connected) to the collector bridge, collector contacts, and / or cooling element, but may be additionally or alternatively connected to any other suitable element of the collector module. In some examples, the electron collector is arranged between the cooling element and the electron emitter, and / or between the cooling element and the chamber (e.g., the entire chamber; a portion of the chamber between the electron collector and the electron emitter (e.g., the portion of the chamber across the electron collector opposite the collector contacts); etc.). However, the cooling element may additionally or alternatively have any other suitable arrangement.

[0068] The electron collector is preferably positioned across the chamber opposite the electron emitter (e.g., where the collector surface of the electron collector faces the electron emitter substantially across the chamber). The collector plane is preferably a substantially flat surface (e.g., defining a collector plane). The collector plane is preferably substantially parallel to the emitter plane, but alternatively may have any other suitable orientation. The space across the chamber between the electron emitter and the electron collector (e.g., inter-electrode spacing) preferably defines a small gap. The gap is preferably 0.1-10 μm, more preferably 0.5-3 μm (e.g., 0.75 μm, 1 μm, 2 μm, etc.), but alternatively may be 50-100 nm, less than 50 nm, 10-25 μm, 25-50 μm, greater than 50 μm, or any other suitable height. The gap may be always present, or it may be present when the TEC is under standard operating conditions (e.g., where the chamber pressure is significantly lower than the ambient pressure (such as atmospheric pressure), where power is supplied to the TEC by the power input, where the TEC temperature is under substantially stable conditions, etc.).

[0069] In some embodiments, an electron collector (e.g., a collector surface) defines a chamber (e.g., such as...) Figures 3A-3B (As shown). Additionally or alternatively, the electron collector may be contained within the chamber (e.g., entirely or substantially entirely within the chamber), such as where the electron collector is located via one or more collector contacts 250 (e.g., as shown). Figures 3C-3D(As shown) Contact (e.g., during system operation, continuously, etc.). Collector contacts preferably contact the electron collector in one or more regions across the electron collector opposite the collector surface (e.g., on the back side opposite the collector surface), but may additionally or alternatively contact the electron collector at any other suitable location. Collector contacts preferably electrically, thermally, and / or mechanically couple the electron collector to other elements of the collector module (e.g., to cooling elements). Therefore, collector contacts preferably comprise one or more conductive and / or thermally conductive materials. Collector contacts may optionally retain the electron collector near other elements of the collector module (e.g., cooling elements), such as by adhesion and / or bonding to the electron collector. Collector contacts may additionally or alternatively retain the electron collector near the electron emitter (e.g., maintaining an inter-electrode gap), preferably retaining the electron collector according to spacers. For example, the collector contacts may include one or more compliant (e.g., deformable) structures compressed between the electron collector and one or more other elements (e.g., cooling elements) of the collector module, thereby applying a force on the electron collector away from the other elements and toward the electron emitter. However, the electron collector may additionally or alternatively be coupled to other elements of the collector module (and / or other elements of the system) in any other suitable manner.

[0070] However, the electron collector may additionally or alternatively include any other suitable elements and / or may have any other suitable arrangement.

[0071] Collector bridges are preferably used to couple electron collectors to one or more other elements of the TEC. Collector bridges preferably mechanically couple (e.g., to a seal) and / or electrically couple (e.g., to collector leads), and may optionally thermally couple electron collectors to other elements of the TEC. Collector bridges preferably comprise one or more metals (e.g., made of one or more of the following, mainly composed of one or more of the following, etc.), such as the same metal as the housing and / or different metals. Collector bridges preferably exhibit a similar coefficient of thermal expansion to the seal, which can help maintain the bond between the collector bridge and the seal. However, collector bridges may additionally or alternatively include any other suitable material.

[0072] The collector bridge preferably includes a planar portion, more preferably a planar portion substantially parallel to the collector plane. The planar portion preferably extends outward from the electron collector (e.g., to or toward a seal). In one example, the planar portion defines a region extending into and / or through the housing of the transmitter module (e.g., a circular region). The collector bridge may additionally or alternatively include one or more non-planar portions (e.g., extending substantially perpendicular to the collector plane) and / or portions having any other suitable shape and / or orientation.

[0073] In some embodiments, some or all of the collector bridge is substantially deformable (e.g., along a direction perpendicular to the collector plane), which can be used to enable movement of the electron collector relative to the electron emitter (e.g., towards and / or away from the electron emitter), such as establishing and / or maintaining a desired inter-electrode spacing. The collector bridge can deform in response to thermal deformation of the TEC element (due to pressure differences between the chamber and the surrounding environment, and / or due to any other suitable forces and / or stresses). In some examples, the deformable element may comprise a foil, corrugated or wave-like structure, and / or any other suitable deformable element. Such a deformable structure may be additionally or alternatively included in the collector module, in the emitter module (e.g., across the seal opposite the collector bridge, along the inner and / or outer shell, within the emitter bridge, etc.), and / or elsewhere in any other suitable location within the TEC.

[0074] However, the collector bridge may additionally or alternatively include any other suitable element arranged in any suitable manner.

[0075] Cooling elements are preferably used to facilitate heat removal from the electron collector (and / or any other suitable element of the TEC, such as other elements of the collector module). Heat removal is preferably convective (e.g., in cooperation with the airflow module), but may additionally or alternatively include radiative, conductive, and / or heat removal via any other suitable mechanism. The cooling element (e.g., in cooperation with the airflow module) preferably maintains the electron collector at or below a target temperature during TEC operation (e.g., a target temperature in the range of 0-100°C, 100-200°C, 200-400°C, 400-600°C, 200-275°C, 250-350°C, 325-400°C, or 275-325°C, such as 300°C). The cooling element is preferably thermally coupled to the electron collector (e.g., via a thermally conductive material, such as a metal). In some examples, the cooling element includes one or more surface modifiers, preferably comprising (e.g., made of) metals that can be used to induce turbulence (e.g., in a heat transfer fluid, such as air within an airflow module) and / or otherwise increase fluid interaction with the cooling element (e.g., heat transfer). Such surface modifiers can include heat sinks, baffles, ribs, recesses, and / or any other suitable structures. For example, the cooling element can include multiple heat sinks (e.g., parallel plates) extending into (and preferably substantially parallel to) the airflow path defined by the airflow module. Figure 2A and / or Figure 2B (As shown).

[0076] The cooling elements are preferably arranged close to the electron collector and / or otherwise configured to preferentially cool the electron collector (e.g., preferentially cooled over other elements of the collector module, preferentially cooled over other elements of the TEC, etc.). This arrangement can provide advantages over alternative arrangements, such as where the cooling elements are arranged close to and / or preferentially cool other elements of the TEC. These other elements may include seals, elements arranged at and / or near the heating chamber opening (e.g., emitter bridges) and / or any other suitable elements. For example, this arrangement can maintain the electron collector at lower temperatures than in other arrangements, such as below 450°C, 400°C, 350°C, 300°C, 250°C, 200°C, 150°C, 100°C, 50°C (or any other suitable temperature), thereby resulting in greater potential device efficiency.

[0077] However, the cooling element may additionally or alternatively include any other suitable element arranged in any suitable manner.

[0078] The collector module may optionally include collector leads. Collector leads can be used to conduct electrical power from the collector module to an external load (e.g., where the TEC electrically drives the external electrical load via emitter and collector leads). Collector leads are preferably conductive. For example, collector leads may include (e.g., are) one or more wires, cables, other metallic structures, and / or any other suitable elements. Collector leads are preferably electrically coupled (more preferably conductively connected) to the electronic collector. Collector leads are preferably connected (e.g., electrically and / or mechanically) to the collector bridge, more preferably at or near the outer portion of the collector bridge (e.g., where the collector bridge meets the seal). However, collector leads may additionally or alternatively connect to any other suitable element of the collector module (e.g., any conductive element electrically connected to the electronic collector).

[0079] In some embodiments, the collector module includes one or more elements such as those described in U.S. Patent Application 15 / 969,027, filed May 2, 2018, entitled “SYSTEM AND METHOD FOR WORK FUNCTION REDUCTION AND THERMIONIC ENERGY CONVERSION” (which is incorporated herein by reference in its entirety), such as the anode of U.S. Patent Application 15 / 969,027 (e.g., where the electron collector is and / or includes the anode of U.S. Patent Application 15 / 969,027).

[0080] However, the collector module may additionally or alternatively include any other suitable elements arranged in any suitable manner.

[0081] 1.1.3 Seals.

[0082] The seal 300 is preferably used for mechanical coupling (e.g., connection) of the transmitter module and the collector module, more preferably, while electrically isolating the transmitter module from the collector module. Preferably, the transmitter module and the collector module are electrically coupled to each other substantially only through an external load via transmitter leads and collector leads and / or via electrons emitted through the chamber.

[0083] The seal preferably comprises one or more electrically insulating materials, more preferably materials capable of withstanding the sealing temperatures during TEC operation (e.g., without melting, deforming, and / or decomposing). This material is preferably glass and / or ceramic (e.g., bulk ceramic, deposited ceramic, etc.; crystalline and / or amorphous ceramic). For example, the seal may comprise one or more boride, carbide, oxide, and / or nitride materials and / or any other suitable material. In a particular example, the seal comprises one or more of alumina (e.g., sapphire, amorphous alumina, etc.), aluminum nitride, silicon dioxide, silicate glass, silicon, silicon carbide, silicon nitride, and / or any other suitable material.

[0084] The seal is preferably disposed between the collector bridge and the transmitter module housing, more preferably at or near the first end of the housing. The seal preferably mechanically connects the collector bridge to the housing (e.g., as shown in the image). Figure 2A , Figure 3A and / or Figure 4 (As shown). In alternative embodiments (e.g., where the housing is an element of the collector module, such as being electrically connected to the electron collector rather than the electron emitter), a seal may be arranged between the housing and the inner housing, preferably mechanically (and preferably not electrically) connecting the housing to the inner housing (e.g., in an example where the emitter bridge is part of the inner housing, connecting the housing to the emitter bridge), such as via Figure 2B and / or Figure 5 The example is shown in the diagram. However, the seal may be additionally or alternatively arranged at any other suitable location in the TEC, preferably mechanically (and preferably not electrically) connecting the transmitter module to the collector module at the respective boundary between the transmitter and collector modules (e.g., the portion of the transmitter module furthest from the electron emitter along the direct conduction path; the portion of the collector module furthest from the electron collector along the direct conduction path) or near it. Those skilled in the art will recognize that the TEC can tolerate (e.g., compared to other electrical devices) some parasitic electrical short circuits (e.g., between the transmitter and collector modules, such as through the seal). For example, in a TEC with an output voltage of approximately 1V, a 10Ω parasitic short circuit between the transmitter and collector modules would result in a current output loss of approximately 0.1A, which is acceptable. Therefore, those skilled in the art will recognize that in some examples, elements of the TEC (e.g., the seal) that are not intended to electrically connect other elements (e.g., the transmitter and collector modules) can still provide parasitic conduction paths (e.g., with resistances greater than 100Ω, 10Ω, and / or 1Ω, etc.).

[0085] A seal can be bonded (e.g., brazed) to one or both elements to which it is attached. Alternatively, a seal can be deposited onto one of the elements to which it is attached and / or which may be otherwise attached.

[0086] In some embodiments, the seal is substantially flat and preferably defines a coverage area that substantially matches (e.g., overlaps) one or more surfaces to which it is attached (e.g., the outer periphery of the housing surface and the collector bridge surface, etc.). In other embodiments, the seal defines a shape complementary to the housing (e.g., a cylindrical housing in embodiments where the housing is cylindrical, a hexagonal prism in embodiments where the housing is hexagonal), such as in which the collector bridge is attached to the inner surface of the seal and the housing is attached to the outer surface of the seal (e.g., a wall across the seal (preferably a wall defining the housing) is opposite the inner surface). In one example, the seal has a thickness of less than 10 mm (e.g., 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 5 mm, 0.05-0.2 mm, 0.2-1 mm, 1-3 mm, or 3-10 mm) and a width in the range of 10-100 mm, preferably 20-50 mm (e.g., a circular shape defining a diameter in the range of 20-50 mm).

[0087] However, the seal may additionally or alternatively include any other suitable element arranged in any suitable manner.

[0088] 1.1.4 Spacers.

[0089] The TEC may optionally include a spacer 400. The spacer can be used to maintain a separation distance (e.g., a minimum separation distance) between the electron emitter and the electron collector. In one example, the spacer includes one or more elements, such as those described in U.S. Patent Application 16 / 044,215, filed July 24, 2018, entitled “SMALL GAP DEVICE SYSTEM AND METHOD OF FABRICATION,” which is incorporated herein by reference in its entirety.

[0090] The spacer is preferably disposed in the chamber between the electron emitter and the electron collector. The spacer may be attached to one or both of the electron emitter and the electron collector and may be held in place by compressive forces (e.g., compressive forces caused by thermal expansion of the TEC components, pressure differentials between the chamber and the surrounding environment, etc.) and / or in any other suitable manner. The spacer preferably does not form a completely continuous layer (e.g., does not obstruct the entire line of sight between the electron emitter and the electron collector). For example, the spacer may be a porous layer, an aggregate of dispersed objects (e.g., microspheres, rods, mesa, etc.) and / or may have any other suitable structure. However, alternatively, the spacer may be a continuous layer.

[0091] The spacer thickness (defined along a direction from the electron emitter to the electron collector, such as perpendicular to the emitter plane and / or collector plane) preferably establishes a substantially uniform spacing between the electron emitter and the electron collector (e.g., having a substantially uniform thickness at the point where the spacer contacts the electron emitter and the electron collector). In one example, the spacer comprises an assembly of dispersed microspheres, the thickness of which is defined as equal to the diameter of the microspheres (e.g., the diameter of the largest microsphere in the assembly). The spacer preferably spans substantially the entire area of ​​the electron emitter-electron collector overlap, but may additionally or alternatively span a subset of it, span areas outside the overlap, and / or have any other suitable shape or extent.

[0092] The spacer preferably comprises one or more electrical insulators (e.g., includes one or more electrical insulators, is made of one or more electrical insulators, is mainly composed of one or more electrical insulators, etc.) such that the spacer does not electrically connect the emitter module and the collector module. The material is preferably capable of withstanding high temperatures (e.g., electron emitter temperatures during TEC operation) without melting, deforming, and / or decomposing. The material may optionally exhibit low thermal conductivity, which can reduce heat conduction from the electron emitter to the electron collector.

[0093] The spacer 400 preferably comprises one or more thermally and / or electrically insulating materials (e.g., materials made therefrom). This material may comprise oxide compounds (e.g., metal and / or semiconductor oxides) and / or any other suitable compounds, such as metal and / or semiconductor nitrides, oxynitrides, fluorides, and / or borides. For example, the material may comprise oxides of Al, Be, Hf, La, Mg, Th, Zr, W, and / or Si, and / or variants thereof (e.g., yttrium-stabilized zirconium oxide). The spacer material is preferably substantially amorphous, but may additionally or alternatively have any suitable degree of crystallinity (e.g., semi-crystalline, nanocrystalline and / or microcrystalline, single crystal, etc.). However, the spacer 400 may additionally or alternatively include any other suitable material (e.g., the relevant materials described above).

[0094] The spacer may comprise a combination of two or more materials (e.g., a combination that can modulate material properties, protect less stable materials, etc.), but may alternatively comprise a single material. The material combination may include alloys, mixtures (e.g., isotropic mixtures, anisotropic mixtures, etc.), multilayer stacks, and / or any other suitable combination. For example, multilayer stacks may reduce thermal and / or electrical conductivity (e.g., due to carrier boundary scattering), and / or increase the stability of the spacer (e.g., in high-temperature, chemically reactive environments, etc.), such as by partially or wholly encapsulating less stable materials within layers of more stable materials. In a first specific example, spacer 400 is made of a hafnium aluminate alloy. In a second specific example, the spacer 400 comprises a multilayer (e.g., three-layer) structure having an intermediate layer (e.g., comprising alumina or an alumina-containing compound (such as a hafnium-alumina alloy); comprising hafnium or a hafnium-containing compound (such as a hafnium-alumina alloy); preferably composed primarily of such material), the intermediate layer being between (e.g., primarily encapsulated therebetween) two outer layers (e.g., comprising hafnium or a hafnium-containing compound (such as a hafnium-alumina alloy different from the intermediate layer); comprising alumina or an alumina-containing compound (such as a hafnium-alumina alloy different from the intermediate layer); preferably composed primarily of such material), the two outer layers having the same or different materials from each other, which can be used, for example, to reduce the evaporation and / or crystallization of the material (e.g., Al, Hf, etc.) in the intermediate layer at high temperatures. In this second specific example, the first outer layer preferably contacts the inner surface of the first electrode, and the second outer layer preferably contacts the inner surface of the second electrode.

[0095] Material combinations and / or surface functionalizations (e.g., terminations such as hydrogen, hydroxyl, hydrocarbons, nitrogen, thiols, silanes, etc.) can additionally or alternatively be used to modify (e.g., enhance, reduce) surface adhesion (e.g., surface adhesion to the inner surface of the electrode), thermal and / or electrical contact, diffusion (e.g., interdiffusion), chemical reactions, and / or any other suitable interfacial properties and / or processes. For example, a spacer may comprise a first layer arranged to contact a first electrode (e.g., an electron emitter or electron collector) and a second layer arranged to contact a second electrode (e.g., the second electrode is opposite the first electrode). In a first example, the first layer exhibits strong adhesion to the first electrode (e.g., the first layer-first electrode interface has a low interfacial energy), and the second layer exhibits weak adhesion to the second electrode (e.g., the second layer-second electrode interface has a high interfacial energy). In a second example, both the first and second layers exhibit weak adhesion to the respective electrodes they contact (e.g., high interfacial energy, substantially equal interfacial energy). In the third example, both the first and second layers exhibit strong adhesion to their respective electrodes (e.g., low interfacial energy, substantially equal interfacial energy). In a particular example, the spacer surface contacting the cathode includes H-terminated surface functionalization, and the spacer surface contacting the anode includes OH-terminated surface functionalization. However, the spacers may include any other suitable combination of materials, and the spacers may additionally or alternatively include any other suitable elements arranged in any suitable manner.

[0096] 1.2 Power input.

[0097] The system may optionally include one or more power inputs 12. The power inputs can be used to heat the electron emitter and / or other components of the emitter module, thereby providing input energy to the TEC. The power input is preferably a burner, more preferably a recuperating burner. However, the power input may alternatively include any other suitable chemical and energy input, radiant heat input, and / or any other heat input and / or other components operable to heat the electron emitter.

[0098] The power input (e.g., a burner) preferably transfers heat (e.g., combustion heat) to the TEC (e.g., to the emitter module, preferably at and / or near the heat receiving area). The heat can be transferred by radiation, convection, conduction, and / or any other suitable means. For example, the power input may be near and / or incident on the flame receiving area of ​​the emitter module to generate a flame.

[0099] The power input is preferably located within the heating chamber. The exhaust gases produced by the burner preferably transfer heat (e.g., from themselves) to other components of the system as they exit the heating chamber. For example, the exhaust gases may transfer heat to one or more gases (such as the input gas used by the burner (e.g., air or oxygen, fuel, etc.) and / or the output gas (such as burner exhaust gas)), to the emitter module (e.g., the emitter module housing and / or the emitter bridge), and / or to any other suitable component. The power input may additionally or alternatively enable heat transfer (e.g., radiative heat transfer) between the burner and the emitter module (e.g., the housing).

[0100] However, the power input may additionally or alternatively include any other suitable element arranged in any suitable manner.

[0101] 1.3 Airflow module.

[0102] The system may optionally include one or more airflow modules 13. An airflow module may include one or more fans and / or ducts. The fan (and / or any other suitable element capable of inducing fluid flow, such as a blower, compressor, etc.) preferably induces airflow (and / or flow of any other suitable fluid) at and / or near the TEC cooling element. The flowing air (or other fluid) preferably removes heat from the cooling element (and / or from any other suitable element of the system, such as other elements of the collector module). In some examples, the fan forces air through one or more ducts (e.g., along an airflow path defined by the ducts).

[0103] Conduits may be used to define one or more airflow paths. Conduits preferably guide airflow from the cooling element to the heating chamber (e.g., where the airflow enters the heating chamber at and / or near the emitter bridge). Air (and / or other fluids) can remove heat from the TEC, thereby heating the air. Heat is preferably removed from the cooling element, but may additionally or alternatively be removed from the housing, inner housing, and / or any other suitable element of the TEC. Air may additionally or alternatively remove heat from the burner, from exhaust gases, and / or from any other suitable heat source. This preheated air is preferably supplied to the burner (e.g., to increase burner efficiency), but may additionally or alternatively be used in any other suitable manner (or may not be used at all).

[0104] However, the airflow module may additionally or alternatively include any other suitable elements arranged in any suitable manner.

[0105] 1.4 Operating temperature.

[0106] In some embodiments, during operation (e.g., when performing method 20 as described below), one or more elements of the TEC are preferably maintained within a temperature range such as that described below. For example, the temperature range can be increased under substantially stable operating conditions where the power input within the heating chamber is in the range of 0-5000W (e.g., 150-300W, 150-200W, 200-250W, 250-300W, 300-500W, 500-1000W, 1000-2000W, or 2000-5000W, etc.) and / or the electrical power output generated by the TEC is in the range of 0-2500W (e.g., 0-10W, 10-20W, 20-40W, 40-60W, 60-100W, 100-200W, 200-500W, 500-1000W, or 1000-2500W, etc.).

[0107] In these embodiments, the electron transmitter preferably has a temperature above 500°C (e.g., a temperature in the range of 500-800°C, 800-1000°C, 1000-1600°C, 1100-1400°C, 1000-1200°C, 1200-1300°C, 1300-1400°C, 1400-1600°C, or 1600-2000°C, or a temperature above 2000°C), more preferably above 1000°C. The inner shell temperature preferably decreases (e.g., monotonically, such as strictly monotonically) along one or more paths (e.g., conduction paths defined by the inner shell) from the electron transmitter to the transmitter bridge (which is preferably at a lower temperature than the electron transmitter). The transmitter bridge preferably has a temperature significantly lower than that of the electron transmitter, such as at least below the threshold temperature difference (e.g., 100°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 900°C, 1000°C, 1200°C, 100-300°C, 250-750°C, 400-600°C, 600-800°C, 800-1200°C). The temperature range is preferably 100°C or higher (e.g., 300-1200°C, 100-400°C, 300-500°C, 500-1000°C, 1000-1200°C, 600-700°C, 700-800°C and / or 800-1000°C, etc.), more preferably in the range of 300-900°C (e.g., 300-600°C, 600-800°C or 750-900°C). The housing temperature preferably decreases (e.g., monotonically, such as strictly monotonically) along one or more paths from the transmitter bridge to the seal and / or to the transmitter leads (e.g., conduction paths defined by the housing) (each of which preferably has a temperature lower than that of the electron transmitter). The temperature difference between the seal and the transmitter bridge is preferably less than (but may also be greater than or substantially equal to) the temperature difference between the transmitter bridge and the electron transmitter. The temperature difference between these temperature differences is preferably greater than 50°C (e.g., 50-100°C, 100-150°C, 150-300°C, or greater than 300°C), more preferably greater than 100°C. The temperature of the seal is preferably below 600°C (e.g., 300-450°C, 450-600°C, or less than 300°C), more preferably less than 450°C. Therefore, the transmitter module temperature preferably decreases (e.g., monotonically, such as strictly monotonically,) along one or more paths from the electron transmitter to the seal and / or to the transmitter leads (e.g., conduction paths defined by the transmitter).

[0108] In these embodiments, the electron collector preferably has a temperature below 700°C (e.g., 100-600°C, 150-350°C, 200-300°C, 500-700°C, or below 100°C, etc.), more preferably below 400°C. The electron collector is preferably at the same lower temperature as the seal, but may alternatively be at a higher temperature or have substantially the same temperature. For example, the temperature difference between the electron collector and the seal can be greater than 50°C (e.g., 50-100°C, 100-150°C, 150-300°C, or greater than 300°C, etc.), more preferably greater than 100°C.

[0109] In some examples (e.g., where the power input is 180-200W and / or the electrical power output is 20-30W, where the electron emitter is maintained at approximately 1200°C and / or the cooling element is maintained at approximately 300°C, etc.), the operating temperature of one or more components of the TEC is equal to... Figure 6B The temperatures shown are within or within their threshold ranges (e.g., within 150°C, 100°C, 75°C, 50°C, 30°C, or 15°C, etc.). While Figure 6 depicts a specific axisymmetric example of a TEC (symmetric about the cylindrical axis), other examples of TECs may also exhibit similar temperatures (e.g., within the threshold range) and / or temperature differences (e.g., where the element temperatures differ from those shown in Figure 6, but the absolute difference and / or proportional difference between the element temperatures are within the threshold range of the temperature differences depicted in Figure 6; where the absolute difference threshold range may be within the range of 150°C, 100°C, 75°C, 50°C, 30°C, or 15°C, etc.; and / or where the proportional difference threshold range may be within 1%, 2%, 5%, 10%, 15%, 20%, 25%, or 50% of the absolute temperature of one of the elements, etc.), and / or may exhibit any other suitable temperature characteristics.

[0110] The thermal resistance of the transmitter module from the electron transmitter to the seal is preferably greater than a threshold value (e.g., 5 K / W, 10 K / W, 15 K / W, 20 K / W, 25 K / W, 30 K / W, 40 K / W, 50 K / W, 3-10 K / W, 10-20 K / W, 20-30 K / W, or 30-50 K / W, etc.). The thermal resistance of the inner shell (from the electron transmitter to the transmitter bridge) is preferably greater than the thermal resistance of the outer shell (from the transmitter bridge to the seal), such as by defining a thermal resistance ratio greater than a threshold value by an amount (e.g., at least 1.1 times, 1.2 times, 1.3 times, 1.5 times, 2 times, 2.5 times, or 3 times, etc.).

[0111] However, the components of a TEC may additionally or alternatively have any other suitable temperature (e.g., during operation) and / or the TEC may additionally or alternatively exhibit any other suitable thermal properties.

[0112] 1.5 Materials.

[0113] The components of the system may include any suitable material and / or combination of materials (e.g., made of them). The material may include semiconductors, metals, insulators, 2D materials (e.g., 2D topological materials, monolayer materials, etc.), organic compounds (e.g., polymers, small organic molecules, etc.) and / or any other suitable material type.

[0114] Semiconductors may include group IV semiconductors (such as Si, Ge, SiC and / or alloys thereof); group III-V semiconductors (such as GaAs, GaSb, GaP, GaN, AlSb, AlAs, AlP, AlN, InSb, InAs, InP, InN and / or alloys thereof); group II-VI semiconductors (such as ZnTe, ZnSe, ZnS, ZnO, CdSe, CdTe, CdS, MgSe, MgTe, MgS and / or alloys thereof); and / or any other suitable semiconductor. Semiconductors may be doped and / or intrinsic. Doped semiconductors are preferably doped with low-diffusion-rate dopants, which minimizes dopant migration (e.g., at high temperatures). For example, n-type Si is preferably doped with P and / or Sb, but may additionally or alternatively be doped with As and / or any other suitable dopant, and p-type Si is preferably doped with In, but may additionally or alternatively be doped with Ga, Al, B and / or any other suitable dopant. Semiconductors can be single-crystal, polycrystalline, microcrystalline, amorphous, and / or have any other suitable crystallinity or mixtures thereof (e.g., including microcrystalline regions surrounded by amorphous regions).

[0115] Metals can include alkali metals (e.g., Li, Na, K, Rb, Cs, Fr), alkaline earth metals (e.g., Be, Mg, Ca, Sr, Ba, Ra), transition metals (e.g., Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Zr, Nb, Mo, Au, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Ir, Pt, Hg, Ga, Tl, Pb, Bi, Sb, Te, Sm, Tb, Ce, Nd), and post-transition metals (e.g., Al, Zn, G). a, Ge, Cd, In, Sn, Sb, Hg, Tl, Pb, Bi, Po, At), metalloids (e.g., B, As, Sb, Te, Po), rare earth elements (e.g., lanthanides, actinides), synthetic elements (e.g., Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg, Cn, Nh, Fl, Mc, Lv, Ts), any other suitable metallic element and / or any suitable alloy, compound and / or mixture of other metallic elements.

[0116] The insulator may include any suitable insulating (and / or wide-bandgap semiconductor) material. For example, the insulator may include insulating metals and / or semiconductor compounds, such as oxides, nitrides, carbides, oxynitrides, fluorides, borides and / or any other suitable compounds.

[0117] The 2D material can include any suitable 2D material. For example, the 2D material can include graphene, BN, metal dichalcogenides (e.g., MoS2, MoSe2, etc.) and / or any other suitable material. However, the system can include any other suitable material.

[0118] The components of the system may include any suitable alloys, compounds and / or other mixtures of materials (e.g., the aforementioned materials, other suitable materials, etc.) in any suitable arrangement (e.g., multilayers; superlattices; materials with microstructural elements such as inclusions, dendrites, lamellae, etc.).

[0119] However, the system may additionally or alternatively include any other suitable elements, in any suitable arrangement, including any suitable components and / or functions.

[0120] 2. Methods.

[0121] The method 20 for generating thermionic energy preferably includes receiving power, emitting electrons, and receiving the emitted electrons, and may optionally include convective heat transfer and / or any other suitable element (e.g., such as...). Figure 7 (As shown). This method is preferably performed using the system 10 described above for the generation of thermal ion energy, but may be performed additionally or alternatively using any other suitable system.

[0122] The method for generating thermionic energy is preferably used to generate electrical output (e.g., to provide electrical power to an external load). The method preferably includes receiving power, emitting electrons, and receiving the emitted electrons. The method may optionally include convective heat transfer. However, the method may additionally or alternatively include any other suitable elements.

[0123] The receiving power is preferably performed within the heating chamber, more preferably near the electron emitter (e.g., in the inner shell, such as adjacent to the electron emitter). This power is preferably thermal power, but may additionally or alternatively include power from any other suitable source. The method may optionally include providing the received power. The power is preferably provided by a power input. The power is preferably provided continuously, but may alternatively be provided at any other suitable timing. In one example, providing power includes operating a burner (e.g., a burner arranged within the heating chamber) with one or more flames proximate and / or incident on the flame receiving region of the emitter module, wherein the received power includes receiving heat from the flames in the flame receiving region. However, the received power may additionally or alternatively include any other suitable elements performed in any suitable manner.

[0124] The emission of electrons is preferably performed at (and / or near) an electron emitter. In response to received power (e.g., in response to the electron emitter reaching high temperatures, such as temperatures greater than 400-500°C, 500-600°C, 600-700°C, 700-800°C, 800-1000°C, 1000-1600°C, or 1600-2000°C), the electron emitter preferably emits electrons (e.g., thermionic emission). The electrons are preferably emitted into a chamber, more preferably toward an electron collector. However, the emission of electrons may additionally or alternatively include any other suitable elements performed in any suitable manner.

[0125] The reception of emitted electrons preferably occurs at an electron collector. Electrons are preferably received from the electron emitter via a chamber. When receiving emitted electrons, the electron collector preferably has a lower temperature (and optionally a lower work function) than the electron emitter, which can result in the generation of electrical power from the reception of the emitted electrons. Receiving emitted electrons preferably includes providing the generated electrical power to an external electrical load (e.g., via conductive leads of the emitter and collector modules). However, receiving emitted electrons may additionally or alternatively include any other suitable elements performed in any suitable manner.

[0126] The method may optionally include convective heat transfer. Convective heat transfer can be used to cool the electron collector and / or preheat the burner gas. Convective heat transfer is preferably performed by an airflow module, which can cause one or more fluids (e.g., air) to flow along system components (e.g., along an airflow path defined by one or more ducts of the airflow module). System components along which fluids can flow may include one or more of a cooling element, an emitter module housing, an emitter module inner shell, a burner, and / or any other suitable element. However, convective heat transfer may additionally or alternatively include any other suitable element performed in any suitable manner, and / or the method may additionally or alternatively include any other suitable element performed in any suitable manner.

[0127] Although omitted for brevity, preferred embodiments include every combination and arrangement of various system components and various method processes. Furthermore, the various processes of the preferred methods can be embodied or implemented, at least in part, as a machine configured to receive a computer-readable medium storing computer-readable instructions. The instructions are preferably executed by a computer-executable component preferably integrated with the system. The computer-readable medium can be stored on any suitable computer-readable medium, such as RAM, ROM, flash memory, EEPROM, optical devices (CD or DVD), hard disk drives, floppy disk drives, or any suitable device. The computer-executable component is preferably a general-purpose or special-purpose processing subsystem, but any suitable special-purpose hardware device or hardware / firmware combination device can additionally or alternatively execute the instructions.

[0128] The accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to preferred embodiments, example configurations, and variations thereof. In this regard, each block in a flowchart or block diagram may represent a module, section, step, or portion of code, comprising one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions mentioned in a block may occur in an order other than that indicated in the drawings. For example, two blocks shown consecutively may actually be executed substantially simultaneously, or blocks may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart illustration, and combinations of blocks in the block diagram and / or flowchart illustration, may be implemented by a system based on dedicated hardware or a combination of dedicated hardware and computer instructions to perform the specified function or action.

[0129] As will be appreciated by those skilled in the art from the preceding detailed description and from the accompanying drawings and claims, modifications and alterations can be made to the preferred embodiments of the invention without departing from the scope of the invention as defined in the appended claims.

Claims

1. A system for thermionic energy conversion, comprising a thermionic energy converter TEC defining a chamber, wherein, The TEC includes: Collector module, the collector module including an electron collector; Transmitter module, the transmitter module comprising: - An electron emitter, which is opposite the electron collector across the chamber; - An inner shell defining a heating cavity, wherein the heating cavity is opposite to the chamber across the electron emitter and across the inner shell; - Outer shell, which is opposite the inner shell across the cavity, wherein: --The housing includes conductive elements, and --The outer casing is electrically connected to the electron transmitter via the inner casing; and - A transmitter bridge, which mechanically, electrically, and thermally connects the inner housing and the outer housing; and A seal, comprising an electrical insulator, is disposed between the housing and the collector module; in: The inner shell defines a longitudinal axis, wherein the inner shell defines the heating cavity and surrounds the longitudinal axis; The longitudinal axis intersects the heating cavity, the electron emitter, the electron collector, and a portion of the chamber disposed between the electron emitter and the electron collector; The longitudinal axis does not intersect the inner shell and does not intersect the outer shell; The outer casing surrounds the longitudinal axis and the inner casing, wherein the conductive element is arranged outside the inner casing from the longitudinal axis.

2. The system of claim 1 further includes a regenerative burner disposed within the heating chamber, wherein the regenerative burner heats the electron transmitter.

3. The system according to claim 2, wherein: The electron transmitter is attached to and thermally coupled to a heat-receiving region of the inner shell, wherein the electron transmitter is disposed between the chamber and the heat-receiving region; and The regenerative burner releases heat within the heating chamber, thereby heating the electron transmitter through the heat receiving area.

4. The system according to claim 1, wherein, The collector module also includes a cooling element thermally coupled to the electron collector.

5. The system of claim 4, further comprising a conduit defining an airflow path from the cooling element to the heating chamber, wherein: The outer casing is disposed between the conduit and the heating chamber; and The conduit thermally couples the air inside the conduit to the outer shell.

6. The system according to claim 5, further comprising a regenerative burner disposed within the heating chamber, wherein: The outer casing preheats the air inside the duct; The duct delivers preheated air to the regenerative burner; and The regenerative burner uses the preheated air to burn fuel, thereby heating the electron transmitter.

7. The system according to claim 4, wherein, The cooling element includes multiple metal heat sinks.

8. The system according to claim 1, further comprising: A first lead, which conductively couples the electron collector to an electrical load; and The second lead conductively couples the electron transmitter to the electrical load through the inner shell and the outer shell; The TEC electrically drives the electrical load through the first lead and the second lead.

9. The system according to claim 1, wherein, The inner shell includes: A conductive layer electrically connected to the electron transmitter and electrically connected to the housing; and A flame protection layer is disposed between the conductive layer and the heating chamber.

10. The system according to claim 9, wherein, The electron emitter and the conductive layer together define a continuous metal layer.

11. The system according to claim 9, wherein: The inner shell further includes a sandwich layer disposed between the conductive layer and the flame protection layer, wherein the sandwich layer has a different composition from the flame protection layer, and wherein the sandwich layer includes at least one of the following: graphite, carburizing material, alumina, titanium dioxide, mullite, zirconium diboride, zirconium carbide, titanium nitride and aluminum nitride. The flame protection layer comprises at least one of the following: silicon carbide, mullite, iridium, silicon nitride, Hitemco R512E, and superalloy; and The electron emitter includes at least one of tungsten, ruthenium, molybdenum, niobium, and iridium.

12. The system according to claim 1, wherein, The outer casing includes a heat pipe that thermally couples the seal to the inner casing.

13. The system of claim 1, further comprising steam enclosed within the chamber, wherein, The vapor includes at least one of cesium, barium, and strontium.

14. The system according to claim 1, wherein, The electron collector comprises an n-type semiconductor.

15. The system according to claim 14, wherein, The n-type semiconductor is n-type silicon.

16. The system according to claim 14, wherein: The collector module also includes a bridge; The electron collector is mechanically coupled to the seal via the bridge; and The bridge is made of metal.

17. The system according to claim 1, wherein: The TEC also includes a spacer disposed within the chamber between the electron emitter and the electron collector; The spacer substantially maintains the gap between the electron emitter and the electron collector; and The spacer does not electrically connect the electron transmitter to the electron collector.

18. The system according to claim 17, wherein: The pressure within the chamber is lower than the ambient pressure surrounding the system; and The environmental pressure forces at least one of the electron collector and the electron emitter toward the spacer, such that both the electron collector and the electron emitter come into contact with the spacer.

19. The system according to claim 1, wherein, The TEC is defined as follows: A lateral vector, which is perpendicular to the longitudinal axis, originates from the longitudinal axis, and is oriented outward from the longitudinal axis, wherein the lateral vector intersects the inner shell at a first point and the outer shell at a second point; The first temperature at the first point is more than 200°C higher than the second temperature at the second point.

20. The system according to any one of claims 1-19, wherein: The seal mechanically connects the housing to the collector module, thereby mechanically coupling the housing to the electron collector; The seal does not electrically connect the housing to the collector module; and The chamber is defined by the electron transmitter, the inner shell, the outer shell, the seal, and the collector module.

21. The system according to claim 20, wherein: The transmitter temperature of the electron transmitter is greater than 500°C; and The transmitter module defines a conductive path from the electron transmitter through the inner and outer shells to the seal, wherein the temperature of the transmitter module decreases monotonically along the conductive path.

22. The system according to claim 21, wherein, The lowest temperature along the boundary of the chamber is located in the region of the collector module that is close to and thermally coupled to the electron collector.

23. A method for thermionic energy conversion, comprising the system of any one of the preceding claims: At the electron transmitter, heat input from the heating chamber is received; At the electron transmitter, in response to receiving the heat input, electrons are emitted into the chamber; and At the electron collector, the electrons emitted by the electron emitter are received; in, The TEC generates an electrical output by emitting and receiving electrons.

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