Systems and methods for a direct fusion heat exchanger and neutron generation

Abstract

A direct fusion heat exchanger technology allows for the efficient transfer of fusion plasma heat energy to a working fluid for aerospace propulsion and other applications. Aspects of this disclosure also enable the generation of high neutron fluxes for applications like medical isotope production, materials testing, and neutron radiography. The use of a thin-film beam window array allows charged particles from a fusion plasma or accelerator to pass through and directly interact and heat the working fluid or fusion target. The thin-film beam window array offers advantages in efficiency, compactness, and safety compared to traditional fusion reactor designs. The technology also addresses the limitations of existing neutron sources by providing a simpler, cheaper, and more efficient method for generating high neutron fluxes.

Description

PCT Patent Application Attorney Docket No. 009990.00008SYSTEMS AND METHODS FOR A DIRECT FUSION HEAT EXCHANGER AND NEUTRON GENERATIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of, and priority to, U.S. Patent Application No. 63 / 624,755 filed on January 24, 2024, and U.S. Patent Application No. 63 / 624,749 filed on January 24, 2024, the content of which are expressly incorporated herein by reference in their entirety for any and all non-limiting purposes.TECHNICAL FIELD

[0002] This invention relates to the field of fusion energy utilization, particularly for aerospace propulsion, accelerators, neutron generation, neutral beam systems, and medical isotope production.BACKGROUND

[0003] Traditional fusion reactor designs face challenges in efficiently transferring heat from the plasma to a working fluid for power generation or propulsion. Existing approaches often involve complex and inefficient intermediate heat transfer steps, leading to energy losses and limitations in compactness and scalability.

[0004] Furthermore, the development of intense neutron sources is crucial for a wide range of applications across medicine, industry, and scientific research. These applications include:

[0005] Medical Isotope Production: Intense neutron sources are necessary for the efficient production of medical isotopes used in diagnostic imaging, radiotherapy, and other medical treatments. The demand for medical isotopes is increasing rapidly, and existing production methods often rely on aging nuclear fission reactors or accelerators with limited capacity.

[0006] Materials Testing: Neutron-based techniques are essential for characterizing the properties of materials and understanding their behavior under various conditions [1],PCT Patent Application Attorney Docket No. 009990.00008Intense neutron sources enable advanced materials research, including the development of new alloys, polymers, and ceramics for aerospace, energy, and other industries.

[0007] Neutron Radiography: Neutron imaging provides a unique way to visualize the internal structure of objects, complementing traditional X-ray imaging. Intense neutron sources are needed for high-resolution neutron radiography, which has applications in nondestructive testing, security screening, and scientific research.

[0008] The current state-of-the-art in beam window technology for accelerator-based neutron sources is the combination of ion optics, differentially pumped apertures, and / or plasma windows [2-4], While effective, these approaches have limitations in terms of achievable target pressure and total beam current. The proposed thin film beam window array technology aims to overcome these limitations by utilizing advanced materials and protective coatings, enabling a significant leap in performance and opening up new possibilities for neutron source applications.

[0009] Fusion power has long been considered the ultimate energy source for aviation due to its potential for clean, safe, and virtually limitless energy generation. Traditional fusion reactor designs may be too large and complex for aerospace applications. Recent advances in compact fusion technology, such as the development of smaller, more efficient fusion devices, have renewed interest in fusion-powered flight. The potential benefits of fusion-powered aviation are significant: Fusion-powered aircraft could achieve unprecedented flight durations, enabling new missions in Earth observation, surveillance, and long-range transportation. Fusion reactions produce no greenhouse gas emissions, offering a pathway to decarbonize the aviation industry. In addition, the high energy density of fusion fuels would allow for larger payloads and more complex missions. Finally, Fusion reactions are inherently safe, with no risk of meltdown or long-lived radioactive waste.

[0010] Despite the potential, significant challenges remain in developing fusion-powered aircraft. These challenges include the need for compact, lightweight fusion reactors, efficient heat transfer systems, and radiation shielding.PCT Patent Application Attorney Docket No. 009990.00008BREI I SUMMARY

[0011] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. The Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0012] Aspects of this disclosure describe a heat exchanger technology that allows for the direct transfer of fusion plasma heat energy into a working fluid, such as compressed air, for aerospace propulsion and other applications. The technology also addresses the challenge of generating high neutron fluxes for applications like medical isotope production, materials testing, and neutron radiography.

[0013] The embodiments of this invention comprise the use of a thin-film beam window array that allows charged particles from a fusion plasma or an accelerator to directly transit into a working fluid or fusion target. This approach offers several advantages over traditional fusion reactor diverter designs:

[0014] Higher Efficiency: By directly heating the working fluid, the system avoids energy losses associated with intermediate heat transfer steps.

[0015] Longer Lifetimes: The thin-film approach minimizes the embedding of fusion products (Hydrogen and Helium) in the structural materials, reducing damage and increasing component lifetime.

[0016] Compactness: The design allows for a more compact and lightweight heat exchanger, which is crucial for aerospace applications.

[0017] In some examples, a beam window array may be used for extracting thermal energy from a fusion plasma into a working fluid for utilization in a heat engine cycle (e.g. Brayton, Stirling) for electrical energy production.

[0018] In some examples, a beam window array may be used for extracting thermal energy from a fusion plasma into a working fluid for utilization in a propulsion cycle (e.g.PCT Patent Application Attorney Docket No. 009990.00008 turbojet, turbofan, ramjet / scramjet, Magneto-Hydro-Dynamic (MHD)) for thrust production.

[0019] In some examples, a beam window array may be used for extracting energetic ions or neutral particles from an accelerator into a working fluid for utilization in a propulsion cycle (e.g. turbojet, turbojet, ramjet) for thrust production.

[0020] In some examples, a beam window array may be used for extracting energetic ions or neutral particles from an accelerator into a gas or plasma target for production of fusion neutrons. The direct fusion heat exchanger with a thin-film beam window array may have various features that are described herein.

[0021] In some examples, the direct fusion heat exchanger for transferring energy from a source of energetic particles to a working fluid may include a beam window array comprising a plurality of thin film windows. Each of the plurality of thin film windows may be configured to allow passage of said energetic particles while maintaining a pressure differential between a first region and a second region. The first region may comprise said source of energetic particles. The second region may comprise said working fluid, and wherein said thin film windows may be configured to minimize energy deposition from said energetic particles. The source of energetic particles may be a fusion plasma. The source of energetic particles may be an ion or neutral particle beam accelerator. The thin film windows may comprise a material selected from the group consisting of: one or more high temperature solid thin film materials or one or more high yield strength materials. The one or more high temperature solid thin film materials may be Silicon, Silicon Carbide, amorphous-Silicon Carbide, Silicon Nitride, graphene, or combinations thereof. The thin film windows may further comprise a protective coating comprising a low-density, high-porosity material capable of surviving a high temperature gas or plasma environment. The low-density, high- porosity material may be a ceramic aerogel. The heat exchanger system may further comprise a support structure for supporting said beam window array, wherein said support structure may comprise a material selected from the group consisting of titanium, Nickel based alloys, carbon-carbon composite, and combinations thereof. The support structure may further comprise cooling channels configured to circulate aPCT Patent Application Attorney Docket No. 009990.00008 coolant. The working fluid may be selected from the group consisting of compressed air, helium, Nitrogen, Xenon, Supercritical CO2, or combinations thereof.

[0022] In some examples, a method of transferring energy from a source of energetic particles to a working fluid may comprise the following steps: providing a beam window array comprising a plurality of thin film windows; passing said energetic particles through said thin film windows; and heating said working fluid with said energetic particles. The thin film windows may maintain a pressure differential between a first region comprising said source of energetic particles and a second region comprising said working fluid. The source of energetic particles may be a fusion plasma generated by a fusion reactor. The source of energetic particles may be an ion or neutral particle beam generated by an accelerator. The method may further comprise using said heated working fluid to generate thrust in a propulsion system using rotating turbomachinery, ramjet / scramjet, or Magneto-Hydro-Dynamic (MHD) acceleration. The method may further comprise using said heated working fluid to generate electricity using a turbogenerator or Magneto-Hydro-Dynamic (MHD) power extraction.

[0023] In yet other examples, a method of generating neutrons with an accelerator based fusion neutron source may comprise the following steps: providing a beam window array comprising a plurality of thin film windows; passing an ion beam through said thin film windows into a target region; and generating neutrons by interaction of said ion beam with a fusion target material in said target region in gaseous or plasma state.

[0024] These and various other features will be described more fully herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements and in which:

[0026] FIG. 1A shows a top perspective view of an individual element of a fusion heat exchanger with a full beam window array according to one or more aspects described herein;PCT Patent Application Attorney Docket No. 009990.00008

[0027] FIG. IB shows a cross-section of the fusion heat exchanger with the full beam window array from FIG. 1 A according to one or more aspects described herein;

[0028] FIG. 1C shows a top view of another embodiment of a fusion heat exchanger with a full beam window array assembly according to one or more aspects described herein;

[0029] FIG. ID shows a side view of the fusion heat exchanger with the full beam window array assembly from FIG. 1C according to one or more aspects described herein;

[0030] FIG. IE shows the fusion heat exchanger with the full beam window array assembly from FIG. 1C incorporated into a support structure to form a high temperature plenum with airflow inlets and outlets according to one or more aspects described herein;

[0031] FIGS. 2 A and 2B show an exemplary embodiment of a fusion heat exchanger beam window array assembly integrated into an exemplary turbomachinery-based Brayton cycle for energy generation or propulsion according to one or more aspects described herein;

[0032] FIG. 3 shows another exemplary embodiment of a fusion heat exchanger beam window array assembly integrated into an exemplary augm enter stage of a turbojet or turboramjet for propulsion according to one or more aspects described herein;

[0033] FIG. 4 shows another exemplary embodiment of a fusion heat exchanger beam window array assembly integrated into an exemplary Magneto-Hydro-Dynamic (MHD) augmenter stage of a combined cycle propulsion system according to one or more aspects described herein;

[0034] FIG. 5 shows an exemplary process for a fusion heat exchanger beam window array assembly for aerospace propulsion according to one or more aspects described herein; and

[0035] FIG. 6 shows an exemplary embodiment of an accelerator based fusion neutron source with the beam window array assembly integrated into a target stage according to one or more aspects described herein.PCT Patent Application Attorney Docket No. 009990.00008

[0036] Further, it is to be understood that the drawings may represent the scale of different components of one single embodiment; however, the disclosed embodiments are not limited to that particular scale.REFERENCE NUMERALS

[0037] 100 - Beam window array assembly

[0038] 101 - Individual beam window element

[0039] 102 - Energetic ion from accelerator or fusion plasma (ions that pass through BWA)

[0040] 103 - Energetic ion from accelerator or fusion plasma (ions that impact support structure)

[0041] 104 - Beam window support structure

[0042] 105 - Vacuum (low pressure) side

[0043] 106 - High pressure side (working fluid or fusion target)

[0044] 107 - Solid thin film beam window layer

[0045] 108 - Ceramic aerogel protection layers

[0046] 109 - Support structure coolant channels

[0047] 110 - High temperature plenum

[0048] 111 - Airflow inlets and outlets

[0049] 120 - Compact fusor

[0050] 130 - Turbine architecture for aerospace propulsion

[0051] 200 - Compact fusion core

[0052] 201 - Fusion plasma

[0053] 202 - Fusion plasma exhaust

[0054] 203 - Working fluid inlet (cold)

[0055] 204 - Working fluid outlet (hot)

[0056] 210 - Turbojet or turbofan engine

[0057] 220 - Afterburning turbojet engine

[0058] 221 - Augm enter stagePCT Patent Application Attorney Docket No. 009990.00008

[0059] 222 - Augmenter exhaust

[0060] 230 - Turbine based Magneto-Hydro-Dynamic (MHD) combined cycle

[0061] 231 - Magneto-Hydro-Dynamic (MHD) stage ‘augmenter’

[0062] 232 - Magneto-Hydro-Dynamic (MHD) augmenter exhaust

[0063] 233 - Core bypass ducting

[0064] 234 - Magneto-Hydro-Dynamic (MHD) electrodes

[0065] 300 - Ion beam source and accelerator

[0066] 310 - Fusion target chamber

[0067] 311 - High pressure target gas / plasma

[0068] 312 - High energy ions (hydrogen isotopes)

[0069] 313 - Fusion neutron test samplesDETAILED DESCRIPTION

[0070] In the following description of the various embodiments, reference may be made to the accompanying drawings, which form a part hereof, and in which may be shown by way of illustration, various embodiments of the disclosure that may be practiced. It may be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope and spirit of the present disclosure.

[0071] Aspects of this disclosure relate to a direct fusion heat exchanger that allows for the efficient transfer of fusion plasma heat energy to a working fluid for aerospace propulsion and other applications. Aspects of this disclosure also enables the generation of high neutron fluxes for applications like medical isotope production, materials testing, and neutron radiography. The use of a thin-film beam window array allows charged particles from a fusion plasma to pass through and directly heat the working fluid. The thin-film beam window array offers advantages in efficiency, compactness, and safety compared to traditional fusion reactor designs. The technology also addresses the limitations of existing neutron sources by providing a simpler, cheaper, and more efficient method for generating high neutron fluxes.PCT Patent Application Attorney Docket No. 009990.00008

[0072] Generally, fusion direct air heat exchangers may heat air directly with charged particles from fusion plasma over a targeted area, wherein heating a working fluid directly means the highest temperature in system is not structural or surface components. High pressure / density working fluid may absorb ionizing radiation limiting damage to structural materials. A thin film approach may limit embedded fusion products (such as hydrogen and helium) and associated blistering / damage. A key technical challenge may be that the material must be thin enough to transmit charged particles, but strong enough to support pressure differential at high temperature.

[0073] The direct fusion heat exchanger comprises a thin-film beam window array that allows a portion of the fusion plasma to escape the core and pass through. The charged particles in the plasma directly heat a working fluid, which can be compressed air, helium, or sCO2, among others. The thin-film beam window array 100 may be made of a material that can withstand the high temperatures and pressures involved, such as silicon (Si), silicon carbide (SiC), amorphous-silicon carbide (a-SiC), silicon nitride (SiN), graphene, graphene composites, or a combination thereof. The beam window array approach may allow for enclosed gas (e.g. Tritium) and liquid (e.g. Lithium) targets at much higher pressure with lower losses vs. differential pumping or plasma windows.

[0074] Using a solid window to extract energetic charged particles from a fusion plasma or accelerator operating in a high vacuum (<lE-5 Torr) into a high-pressure gas region creates a large pressure differential across the thin-film beam window material. To minimize energy loss, the beam window should be as thin as possible while remaining strong enough to withstand this pressure differential. The power deposited (Pdep) into a single thin film beam window by charged particles with current density J, energy E, (Z / A) is the atomic # to mass ratio, thin film thickness t, density p, and energy loss coefficient x, is given by:Equation 1PCT Patent Application Attorney Docket No. 009990.00008

[0075] Since the efficiency of the fusion heat exchanger will decrease if more of the charged particle energy is deposited into the beam window, we want to make the beam window as thin as possible and particle energy, E, as high as possible. Another way to reduce the deposited energy is to decrease the density, p, of the beam window materials.

[0076] The mechanical stress, G. in the thin film due to the pressure differential (AP), for a single circular beam window of radius ro is given by:Equation 2This yield stress will drive a minimum thickness, tmin, for a single beam window, based on the material yield strength, oyieidEquation 3Where we see that the thickness of the beam window thin film should increase linearly with the window radius ro. This is the primary reason for the array design of the beam window heat exchanger. This allows for the design of large area heat exchanger, while maintaining thin individual beam window elements that support high efficiency extraction of energetic charged particles. By using equation 3 to estimate the beam window thin film thickness, and accounting for beam energy loss in the support structure, we can estimate the total energy loss in the beam window array:Equation 4Where S is the structure factor, defined as the fraction of total beam window surface area composed of the beam window support structure. We find that for a 100 nm- thick Silicon Nitride beam windows, Structure factor of S = 0.95, this beam window array approach could support >10MW / m2beam power density with AP < 50bar.PCT Patent Application Attorney Docket No. 009990.00008

[0077] A thin-film spin-on ultra-high-temperature ceramic (UHTC) aerogel insulator may be used to protect the beam windows from damage and insulate beam windows from target gas and reduce sputtering damage. This aerogel layer may also help to reduce sputtering damage, increasing the lifetime of the heat exchanger. The beam window array may be supported by a high-temperature structure made of materials like titanium or carbon-carbon composite.

[0078] For accelerator-based neutron sources, a large area beam window may be utilized, with square geometry for individual beam windows and a high beam window fraction afforded by DRIE and lithography tools, compared with previous approaches [5], Low sputtering beam target window arrays for fusion neutron sources may use thin film ceramic / semiconductors with low density coating to achieve high power densities, higher target pressure with lower losses. Initial estimates of the beam window array performance are based on 300nm Silicon Nitride beam window arrays with a 5um spin- on Alumina aerogel layer indicate that a liquid cooled solution could be integrated onto a standard vacuum flange could achieve the ion beam current, target pressure, and hydrogen environment survivability to achieve >ldPa / yr fusion neutron damage. This is based on existing 315keV Deuteron-into-Tritium accelerator infrastructure, at a cost that is at least an order magnitude lower than other >dPa / yr facilities [8],

[0079] Porous material or high surface to volume ratio materials have been shown to decrease sputtering rates by approximately an order of magnitude in plasma facing materials [10,11], For example, a ceramic aerogels (e.g. Alumina

[0012] , SiC) as a solution and have adapted a method

[0013] to apply micron-thick aerogel layers onto semiconductor surfaces that is well suited to the beam window sputtering protection layer (FIG. 2A).

[0080] We can estimate the sputtering rate from 315keV ion beam will introduce surface loss at approximately 5nm / hr at 3mA / cm2 fluence. This result gives us confidence that a 3- 5um thick layer of ceramic aerogel will protect the beam windows for several hundred hours of operation. Because of the extremely low density of the aerogel (~10mg / cm3), the layer will have negligible effect on the deuteron beam as it passes through the beam window arrays. Previous works have shown that the introduction of a small percentage of refractory phase with higher dimensional thermal stability (alumina) on silica matrices results in the maintenance of pore stability of silica aerogel up to 1200°C [14-PCT Patent Application Attorney Docket No. 009990.0000816], Additionally, Alumina aerogels also show good mechanical properties, with Young's modulus up to 10 MPa higher than those found for silica aerogels [17, 18],

[0081] FIGS. 1A and IB depict a fusion heat exchanger with a full beam window array assembly. Specifically, FIG. 1 A depicts top perspective view of an individual element of the fusion heat exchanger with the full beam window array 100 and FIG. IB depicts a cross-section of the fusion heat exchanger with the full beam window array 100. As shown in FIGS. 1 A and IB, the fusion beam window array 100 may comprise of several individual beam window array elements 101, arranged in a large array to cover a large surface area. Many of these individual beam window array elements 101 may be supported mechanically by a support structure 104 that can also act to provide a pathway for heat dissipation.

[0082] The beam window array assembly 100 may allow energetic ions or neutral particles 102 / 103 to pass from a source region or low pressure region 105 under vacuum conditions into a high pressure region 106.

[0083] In some other examples, as shown in FIG. 2A, the energetic ions or neutral particles 212 may originate from a fusion plasma 201, where a portion of the plasma particles 212 may escape confinement and may impinge upon the beam window array assembly 100.

[0084] In some other examples, as shown in FIG. 6, the energetic ions or neutral particles 312 may originate from an accelerator, where the energetic ions or neutral particles 312 may be guided with electric and / or magnetic fields towards the surface of the beam window array assembly 100.

[0085] As is shown in FIGS. 1A-1E, individual beam window array elements 101 may be comprised of a solid thin film layer 107 bonded or deposited on a support structure 104 with repeating unit-cell geometry. The support structure 104 may be a MEMS-array support structure with active cooling, such that deposited beam power (Qdep) equals cooling power (Qactive). The individual beam window array elements 101 may be in a repeating unit-cell geometry such as a square array or a hexagonal array. Other repeating unit-cell geometries may be utilized for the individual beam window array elements 101 without departing from aspects of this disclosure.PCT Patent Application Attorney Docket No. 009990.00008

[0086] The solid thin film layer 107 may have a high thermal conductivity in order to effectively dissipate heat to the surrounding support structure 104. The solid thin film layer 107 may also have a density and thickness such that energetic ions or neutral particles 102 / 103 pass through this material without losing significant kinetic energy. This solid thin film layer 107 may also have the mechanical yield strength to withstand the pressure differential caused by the high pressure region 106 and low pressure regions 105.

[0087] The solid thin film layer 107 may be coated with a low density, high porosity material. The solid thin film layer 107 may be a ceramic aerogel. The low density, high porosity material may be located on one or both sides to protect the solid thin film layer 107 from sputtering damage.

[0088] The support structure 104 may also contain active cooling channels 109. The active cooling channels 109 may act as a thermal sink for heat loads from energetic particles that impact the support structure 103 and are absorbed by the thin film solid layer 107. The active cooling channels 109 may pass a coolant, such as water, NaK, or other similar coolants. Passing a coolant through these channels 109 may allow the beam window array assembly 100 to achieve higher beam power densities.

[0089] FIGS. 2 A and 2B depicts an exemplary embodiment of a fusion heat exchanger beam window array assembly 100 integrated into an exemplary turbomachinery -based Brayton cycle for energy generation or propulsion. As shown in FIGS. 2A and 2B, the beam window array assembly 100 may be situated at the plasma exhaust 202 portions of a fusion reactor core. In this case, a high-pressure working fluid 203 (e.g. Air, N2, He) may be brought into the high pressure region 106 of the beam window array assembly 100, forming the basis of a ‘remote-combustor’ where enthalpy is added to a thermodynamic cycle. In this Brayton cycle turbine 210 case, the fusion-heated working fluid 204 may then be brought back into the turbine sections to complete the engine cycle, driving the compressor and providing thrust or electrical power generation.

[0090] FIG. 3 depicts an exemplary embodiment of a fusion heat exchanger beam window array assembly 100 integrated into an exemplary augmenter stage of a turbojet or turboramjet for propulsion. As shown in FIG. 3, the beam window array assembly 100PCT Patent Application Attorney Docket No. 009990.00008 may be situated at the plasma exhaust 202 portions of a fusion reactor core 200 and the entrance of an augmenter 221 stage. In this case, the exhaust of a turbojet 220 turbine stage (or bypass) may be guided into the augmenter 221 stage where the beam window array assembly 100 allows energetic ions charged particles that escape the fusion plasma 202 to directly thermalize in this airflow, which is exhausted through a nozzle 222 to produce thrust.

[0091] FIG. 4 depicts an exemplary embodiment of a fusion heat exchanger beam window array assembly 100 integrated into an exemplary Magneto-Hydro-Dynamic (MHD) augmenter stage of a combined cycle propulsion system. As is shown in FIG. 4, the beam window array assembly 100 may be situated at the plasma exhaust 202 portions of a fusion reactor core 200 and the entrance of a Magneto-Hydro-Dynamic (MHD) augmenter 231 stage. In this exemplary embodiment, the exhaust of a combined cycle turboramjet 233 bypass air may be guided into the MHD augmenter stage. The beam window array assembly 100 may allow energetic ions charged particles that escape the fusion plasma 202 to directly ionize this airflow. The large ionization fraction caused by the fusion plasma exhaust 202 in the augmenter 231 may allow for efficient MHD acceleration of the airflow using potentials applied to electrodes 234 inside of the augmenter 231. The fusion core 200 may produce large magnetic fields for plasma confinement. The fusion core plasma exhaust 202 may be oriented orthogonal to the augmenter 231 axis. The MHD electrodes may be oriented such that MHD acceleration occurs towards the augmenter exhaust 232, resulting in velocity addition to the flow without heating, and efficient thrust generation.

[0092] FIG. 5 depicts an exemplary process for a fusion heat exchanger beam window array assembly for aerospace propulsion. As is shown in FIG. 5, at step A, the fusion heat exchanger building blocks and fusion heat exchanger beam window array assembly may include 3 stages. At the first stage, a solid thin film beam window layer 107 is located on an insulator wafer which creates the beam window support structure 104. The solid thin film beam window layer 107 may include one or more of various materials such as: silicon carbide (SiC), amorphous-silicon carbide (a-SiC), silicon nitride (SiN), graphene, graphene composites, or a combination thereof. At a second stage, an alumina / silica aerogel layer 108 may be spun on the film beam window layer 107. At a third stage, the individual beam window array elements 101 of the fusionPCT Patent Application Attorney Docket No. 009990.00008 heat exchanger beam window array assembly 100 may be created using lithography and / or deep reactive ion etch (DRIE). The individual beam window array elements 101 may be in a repeating unit-cell geometry such as a square array or a hexagonal array.

[0093] Step B in FIG. 5 shows the completed fusion heat exchanger with the full beam window array 100 from step A. Step C in FIG. 5 shows the fusion heat exchanger with the full beam window array assembly 100 incorporated into a support structure to form a high temperature plenum 110 with airflow inlets and outlets 111. Step D in FIG. 5 shows the high temperature plenum 110 with the fusion heat exchanger with the full beam window array 100 integrated into a compact fusor 120. Step E in FIG. 5 shows multiple fusors 120 with the fusion heat exchanger with the full beam window array 100 integrated with turbine architecture 132 to provide aerospace propulsion for an aircraft 130.

[0094] FIG. 6 depicts an exemplary embodiment of an accelerator based fusion neutron source with the beam window array assembly integrated into a target stage. As is shown in FIG. 6, the beam window array assembly 100 may be situated at the end of an accelerator 300, such that energetic ions 312 can impinge on the surface of the beam window array assembly 100, traveling from the low pressure region 105 or vacuum side of the accelerator, into a region of high-pressure target gas or plasma 311 inside of target chamber 310. In this case, the energetic ions 312 may fuse with the target gas / plasma 311 causing neutron emission. These energetic neutrons can be used for materials testing of components of fusion materials 313. Using accelerator beam targets and fusion neutron sources may be used in various applications, such as:

[0095] 1) Higher current and higher-pressure target design for proton beam therapy and cyclotron radiopharmaceutical production providing higher yield and dose rates (e.g. 18F2andnC).

[0096] 2) lower gamma-ray background, smaller target cell and higher fluence for Neutron resonance radiography (NRR) applications: a. Explosives detection with NRR requires compact high flux monoenergetic fast neutron source; andPCT Patent Application Attorney Docket No. 009990.00008 b. Proposed beam window array solution may offer lower x-ray production (lower Z window material) and faster scan times (higher neutron fluence).

[0097] 3) For Deuterium or Tritium gas target fusion neutron sources, would allow for higher pressure and beam current = higher neutron yield and fluence (n / cm2s).

[0098] Additionally, using accelerator beam targets and fusion neutron sources may provide benefits to terrestrial fusion community, such as:

[0099] 1) Simpler, cheaper gas targets with higher neutron fluence for fusion reactor materials testing: a. All DT fusion concepts need materials to withstand 14.1 MeV neutron fluence; b. Current DT neutron generators are not sufficient to reach 10 DPA per year testing requirement; c. Current solid target, differentially pumped, foil window, and plasma window approaches face challenges to reach 10 DPA per year goal (thermal, complexity, Tritium loss, scalability); and d. Proposed silicon beam window array leveraging MEMS processing and strongback support could achieve FPNS yields with enclosed Tritium targets.

[0100] Possibility to incorporate higher pressure power conversion technologies (e.g. open Brayton cycle with air, Helium, sCCh) for cost benefits in terrestrial fusion power plants. Direct injection of fusion products into gas flow = working fluid is the highest temperature component, avoids thermal constraints and heat transfer limitations of traditional divertor approach.

[0101] The present disclosure is disclosed above and in the accompanying drawings with reference to a variety of examples. The purpose served by the disclosure, however, is to provide examples of the various features and concepts related to the disclosure, not to limit the scope of the aspects of this disclosure. One skilled in the relevant art will recognize that numerous variations and modifications may be made to the examples described above without departing from the scope of the present disclosure.PCT Patent Application Attorney Docket No. 009990.00008REFERENCES

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Claims

1. PCT Patent Application Attorney Docket No. 009990.00008We claim:

1. A heat exchanger system for transferring energy from a source of energetic particles to a working fluid, the heat exchanger system comprising: a beam window array comprising a plurality of thin film windows, each of the plurality of thin film windows are configured to allow passage of said energetic particles while maintaining a pressure differential between a first region and a second region, wherein said first region comprises said source of energetic particles, wherein said second region comprises said working fluid, and wherein said thin film windows are configured to minimize energy deposition from said energetic particles.

2. The heat exchanger system of claim 1, wherein said source of energetic particles is a fusion plasma.

3. The heat exchanger system of claim 1, wherein said source of energetic particles is an ion or neutral particle beam accelerator.

4. The heat exchanger system of claim 1, wherein said thin film windows comprise a material selected from the group consisting of: one or more high temperature solid thin film materials or one or more high yield strength materials.

5. The heat exchanger system of claim 4, wherein the one or more high temperature solid thin film materials is Silicon, Silicon Carbide, amorphous-Silicon Carbide, Silicon Nitride, graphene, or combinations thereof.

6. The heat exchanger system of claim 1, wherein said thin film windows further comprise a protective coating comprising a low-density, high-porosity material capable of surviving a high temperature gas or plasma environment.

7. The heat exchanger system of claim 6, wherein said low-density, high-porosity material is a ceramic aerogel.

8. The heat exchanger system of claim 1, further comprising a support structure for supporting said beam window array, wherein said support structure comprises a material selected fromPCT Patent Application Attorney Docket No. 009990.00008 the group consisting of titanium, Nickel based alloys, carbon-carbon composite, and combinations thereof.

9. The heat exchanger system of claim 8, wherein said support structure further comprises cooling channels configured to circulate a coolant.

10. The heat exchanger system of claim 1, wherein said working fluid is selected from the group consisting of compressed air, helium, Nitrogen, Xenon, Supercritical CO2, or combinations thereof.

11. A method of transferring energy from a source of energetic particles to a working fluid, the method comprising: providing a beam window array comprising a plurality of thin film windows; passing said energetic particles through said thin film windows; and heating said working fluid with said energetic particles, wherein said thin film windows maintain a pressure differential between a first region comprising said source of energetic particles and a second region comprising said working fluid.

12. The method of claim 11, wherein said source of energetic particles is a fusion plasma generated by a fusion reactor.

13. The method of claim 11, wherein said source of energetic particles is an ion or neutral particle beam generated by an accelerator.

14. The method of claim 11, further comprising using said heated working fluid to generate thrust in a propulsion system using rotating turbomachinery or Magneto-Hydro-Dynamic (MHD) acceleration.

15. The method of claim 11, further comprising using said heated working fluid to generate electricity using a turbogenerator or Magneto-Hydro-Dynamic (MHD) power extraction.

16. The method of claim 11, wherein said thin film windows comprise a material selected from the group consisting of: one or more high temperature solid thin film materials or one or more high yield strength materials.PCT Patent Application Attorney Docket No. 009990.0000817. The method of claim 16, wherein the one or more high temperature solid thin film materials is Silicon, Silicon Carbide, amorphous-Silicon Carbide, Silicon Nitride, graphene, or combinations thereof.

18. The method of claim 11, wherein said thin film windows further comprise a protective coating comprising a low-density, high-porosity material capable of surviving a high temperature gas or plasma environment.

19. The method of claim 18, wherein said low-density, high-porosity material is a ceramic aerogel.

20. The method of claim 11, wherein the beam window array comprises a support structure for supporting said beam window array, wherein said support structure comprises a material selected from the group consisting of titanium, Nickel based alloys, carbon-carbon composite, and combinations thereof.

21. The method of claim 20, wherein said support structure further comprises cooling channels configured to circulate a coolant.

22. The method of claim 11, wherein said working fluid is selected from the group consisting of compressed air, helium, Nitrogen, Xenon, Supercritical CO2, or combinations thereof.

23. A method of generating neutrons with an accelerator based fusion neutron source, the method comprising: providing a beam window array comprising a plurality of thin film windows; passing an ion beam through said thin film windows into a target region; and generating neutrons by interaction of said ion beam with a fusion target material in said target region in gaseous or plasma state.

24. The method of claim 23, wherein said thin film windows comprise a material selected from the group consisting of: one or more high temperature solid thin film materials or one or more high yield strength materials.PCT Patent Application Attorney Docket No. 009990.0000825. The method of claim 24, wherein the one or more high temperature solid thin film materials is Silicon, Silicon Carbide, amorphous-Silicon Carbide, Silicon Nitride, graphene, or combinations thereof.

26. The method of claim 23, wherein said thin film windows further comprise a protective coating comprising a low-density, high-porosity material capable of surviving a high temperature gas or plasma environment.

27. The method of claim 26, wherein said low-density, high-porosity material is a ceramic aerogel.

28. The method of claim 23, wherein the beam window array comprises a support structure for supporting said beam window array, wherein said support structure comprises a material selected from the group consisting of titanium, Nickel based alloys, carbon-carbon composite, and combinations thereof.

29. The method of claim 28, wherein said support structure further comprises cooling channels configured to circulate a coolant.

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