Jet impingement cooling assembly for a plasma window positioned in a beam accelerator system

Abstract

The beam accelerator system includes an ion accelerator for generating an ion beam, a low-pressure chamber, an anode, a plasma window, and a cathode housing. The plasma window includes a plurality of cooling plates. Each cooling plate includes a central wall surrounding an opening, a cooling chamber surrounding the central wall, one or more impingement channels, and one or more return channels. Each of the impingement and return channels enters the cooling plate from an outer edge of the cooling plate and extends toward the opening to the cooling chamber. Each of the one or more impingement channels is configured to provide an inlet path for cooling fluid to enter the cooling chamber, and each of the one or more return channels is configured to provide an outlet path for heated fluid to exit the cooling chamber.

Description

[Technical Field]

[0001] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This disclosure was developed with government support under Contract No. DE-AR0001377 awarded by the U.S. Department of Energy. The government has certain rights in this disclosure.

[0002] FIELD OF THE INVENTION This specification relates generally to plasma window systems, and more particularly to cooling plates for plasma window systems used in beam accelerator systems, such as gas target neutron generation systems. [Background technology]

[0003] Beam accelerator systems are used to produce medical-grade radioisotopes used by physicians in nuclear medicine. Typically, beam accelerator systems include an ion accelerator that generates a high-energy ion beam that is directed through a plasma window into a target chamber. For example, in a gas target neutron production system, the high-energy ion beam is directed toward a gas target. The generation and transport of the high-energy ion beam relative to the target requires a large amount of energy and generates a large amount of heat.

[0004] Therefore, a need exists for components of beam accelerator systems, such as gas target neutron generation systems, that help reduce the cost and energy required to produce neutrons and potentially radioisotopes. Summary of the Invention

[0005] In one embodiment, a beam accelerator system includes an ion accelerator for generating an ion beam, a low-pressure chamber, an anode adjacent to and fluidly connected to the low-pressure chamber, a plasma window adjacent to and fluidly connected to the anode, and a cathode housing adjacent to and fluidly connected to the plasma window, wherein the plasma window includes a plurality of cooling plates, each cooling plate including an opening aligned with an opening in one or more adjacent cooling plates to form a plasma channel, wherein one or more cooling plates of the plurality of cooling plates include a central wall surrounding the opening, a cooling chamber surrounding the central wall, one or more impingement channels entering the cooling plate from an outer edge thereof and extending toward the opening to the cooling chamber, and one or more return channels entering the cooling plate from the outer edge thereof and extending toward the opening to the cooling chamber, wherein each of the one or more impingement channels is configured to provide an inlet path for a cooling fluid to enter the cooling chamber and each of the one or more return channels is configured to provide an outlet path for a heated fluid to exit the cooling chamber.

[0006] According to one embodiment, a method comprises generating a plasma in a plasma channel of a plasma window, the plasma window being positioned between and fluidly coupled to an anode and a cathode housing, a plurality of cathodes housed in the cathode housing, the plasma window comprising a plurality of cooling plates, each cooling plate having an opening aligned with the openings of one or more adjacent cooling plates to form a plasma channel, one or more cooling plates of the plurality of cooling plates having a central wall surrounding the opening, a cooling chamber surrounding the central wall, and a cooling plate extending from an outer edge of the cooling plate into the opening and into the cooling chamber. and one or more impingement channels entering the cooling plate from an outer edge of the cooling plate and extending toward the opening to the cooling chamber, the method further comprising: directing an ion beam generated by an ion accelerator from the low-pressure chamber through a plasma disposed in the plasma channel of the plasma window into a target chamber containing a target gas; and directing a cooling fluid through the one or more impingement channels such that the cooling fluid impinges against the central wall and transfers heat from the central wall to the cooling fluid, and thereafter flows into the one or more return channels as a heated cooling fluid. [Brief explanation of the drawings]

[0007] [Figure 1] 1 illustrates a schematic diagram of a gas target neutron production system according to embodiments disclosed and described herein. [Figure 2A] 1A and 1B show schematic diagrams of a low-pressure chamber, an anode, a plasma window, a cathode housing, and a cathode according to embodiments disclosed and described herein. [Figure 2B] 1A and 1B show schematic cross-sections of a low-pressure chamber, an anode, a plasma window, a cathode housing, and a cathode according to embodiments disclosed and described herein. [Figure 3] 1A and 1B show schematic cross-sections of an anode, plasma window, and cathode housing according to embodiments disclosed and described herein. [Figure 4A] 1A and 1B show schematic diagrams of a front view of a plate having a four-way jet impingement cooling channel design according to embodiments disclosed and described herein; [Figure 4B] 1A and 1B show schematic side views of a plate with an opening extending through the plate near the geometric center of the plate. [Figure 5] 1A and 1B show schematic diagrams of a front view of a plate with a refractory metal slug according to embodiments disclosed and described herein; [Figure 6A] 10 graphically illustrates temperature and pressure drop versus flow rate for a plate having a four-way jet impingement cooling channel design according to embodiments disclosed and described herein. [Figure 6B] 10 shows a graph of temperature and pressure drop versus flow rate for a plate with two circular parallel cooling channels. [Figure 7A] 10 illustrates a graph of opening temperature versus flow rate for a plate with a four-way jet impingement cooling channel design and for a plate with two circular parallel cooling channels according to embodiments disclosed and described herein. [Figure 7B] 10 graphically illustrates cooling channel temperature versus flow rate for a plate with a four-way jet impingement cooling channel design and for a plate with two circular parallel cooling channels according to embodiments disclosed and described herein. DETAILED DESCRIPTION OF THE INVENTION

[0008] Additional features and advantages will be described in the detailed description which follows, and in part will become readily apparent to those skilled in the art from that description, or will be learned by practicing the embodiments described herein, including the detailed description which follows, the claims, and the accompanying drawings.

[0009] It should be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments described herein and, together with the description, serve to explain the principles and operation of the claimed subject matter.

[0010] Reference will now be made in detail to embodiments of a cooling plate for use in a plasma window of a beam accelerator system, embodiments of which are illustrated in the accompanying drawings, in which, where possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0011] According to embodiments, a plasma window is positioned within a gas target neutron generation system to act as a windowless vacuum barrier separating a low-pressure beamline from a high-pressure gas target chamber. The plasma window enables systems with increased gas target pressures, shorter target lengths, and increased currents to the target (e.g., target gas present in the target chamber). In this regard, beam accelerator systems built with plasma windows can increase available neutron flux by up to two orders of magnitude compared to conventional beam accelerator systems.

[0012] Referring to FIG. 1 , an embodiment of a beam accelerator system 100 includes an ion accelerator 110 that generates a high-energy ion beam 111 directed through a low-pressure chamber 120. The beam accelerator system 100 is operable to generate neutrons through a fusion reaction. These neutrons may be used, for example, to perform neutron radiography, generate medical isotopes, transmute radioisotopes, such as waste radioisotopes generated during the operation of a fusion power plant, and generate fusion power. In an embodiment, the low-pressure chamber operates in a vacuum or near-vacuum. An anode 130 is positioned adjacent to and fluidly connected to the low-pressure chamber 120 and is separated from a cathode housing 150 by a plasma window 140. The plasma window 140 is adjacent to and fluidly connected to both the anode 130 and the cathode housing 150. In an embodiment, the anode 130 may be an anode plate. The cathode housing 150 is configured to house multiple cathodes 151. This will be described in more detail below. The beam accelerator system 100 also includes a target chamber 160 for containing a target gas, such as deuterium, tritium, helium, or argon. The target chamber 160 and the cathode housing 150 are pressurized such that the cathode housing 150 is the high-pressure side of the beam accelerator system 100 and the anode 130 is the low-pressure side (e.g., vacuum side) of the beam accelerator system 100. Gases produced by the ion accelerator 110 and gases present in the low-pressure chamber 120 do not migrate through the anode 130 to the plasma window 140 or the cathode housing 150 due to the pressure difference between the low-pressure side of the beam accelerator system 100 and the high-pressure side of the beam accelerator system 100. It should be understood that FIG. 1 is for illustrative purposes only and is not drawn to scale. It should be noted that in some embodiments, the positions of the anode and cathode may be reversed. Without being bound by theory, it is believed that such an embodiment may be beneficial when coupled with a neutron producing target, for example, to increase the available sample volume in the high flux region.

[0013] Conventionally, accelerating ions into a gas target chamber (such as target chamber 160), which in the embodiment shown in FIG. 1 is fluidly coupled to and adjacent to cathode housing 150, requires large and expensive pumping equipment to maintain the low pressure required for ions to be accelerated from ion accelerator 110. The lower limit of the pressure in the target chamber is generally determined by the minimum pressure required to stop the incident ion beam. The length of target chamber 160 can affect the lower limit of the pressure. In embodiments, the lower limit of the pressure in target chamber 160 can be 1 torr, 5 torr, 10 torr, 15 torr, 20 torr, 30 torr, 50 torr, 100 torr, or 500 torr. The upper limit of the pressure in target chamber 160 is generally controlled by the ability of the pumping system to maintain the required pressure differential. Larger ion beam sizes and higher current ion beams require greater pumping action due to the conductance of the ion beam through the channel and into the target. Therefore, the beam size and resulting total system yield is limited by the channel diameter into the target chamber.

[0014] The use of a plasma window 140 between the anode 130, which is at a low pressure (e.g., near vacuum), and the cathode housing 150, which is at a high pressure, allows for a larger pressure reduction factor than conventional channels, facilitating the use of larger diameter and higher power ion beams. The pressure reduction gain also reduces the overall cost of the pumping configuration due to the reduction in conductance and pumping configuration hardware required to maintain the pressure differential.

[0015] FIG. 2A is a side view of the low-pressure chamber 120, anode 130, plasma window 140, cathode housing 150, and cathode 151. As shown in FIG. 2A, the plasma window 140 includes multiple plates connected adjacent to one another. In embodiments, the plasma window 140 includes four to eight plates, such as five to seven plates or six plates. As described above, the plasma window 140 is positioned between the anode 130 and the cathode housing 150, and the plasma window 140 is connected to both the anode 130 and the cathode housing 150. The cathode housing 150 is configured to support multiple cathodes 151. In embodiments, the cathode housing 150 is configured to support four cathodes, three cathodes, or two cathodes. In embodiments where the cathode housing is configured to support four cathodes, the cathodes 151 may be positioned at approximately 90° to one another within the cathode housing 150. In embodiments where the cathode housing 150 is configured to support three cathodes, the cathodes 151 may be positioned at approximately 120° relative to one another. In embodiments where the cathode housing 150 is configured to support two cathodes, the cathodes 151 may be positioned at approximately 180° relative to one another.

[0016] 2B is a cross-sectional view of the low-pressure chamber 120, anode 130, plasma window 140, and cathode housing 150 shown in FIG. 2A. The anode 130, in an embodiment, is a grounded plate with a nozzle 131 fluidly connected to the low-pressure chamber 120. The nozzle 131 is also fluidly connected to a channel 132 positioned within the anode 130. As described in more detail below, the nozzle 131 and channel 132 in the anode 130 operate to focus the ion beam from the low-pressure side of the beam accelerator system 100 into the plasma window 140. To this end, in one or more embodiments, the anode and / or low-pressure chamber 120 are attached to and fluidly connected to a pumping system.

[0017] 2B , the plasma window 140 includes five adjacent plates 142 interconnected to separate the anode 130 from the cathode housing 150. It should be understood that embodiments of the plasma window 140 may include more or fewer than five plates 142. Each plate 142 of the plasma window 140 includes a circular opening at or near the geometric center of the plate 142. The circular openings of each plate 142 are aligned about a central axis such that, when multiple plates 142 are aligned and connected, the coaxial circular openings of the plates 142 form a plasma channel 141 through which the high-energy ion beam travels from the anode 130 to the cathode housing 150. It should be understood that, in embodiments, the openings of the plates 142 need not be perfectly circular, but may be any shape suitable for transmitting the high-energy ion beam. In embodiments, the plates 142 of the plasma window 140 are electrically floating and cooled with a fluid, such as water, as will be described in more detail below. By configuring the plates 142 to be electrically floating, the voltage gradient across the plasma channel 141 is not as steep as it would be if the plates 142 were grounded. This may aid in the transmission of the high-energy ion beam across the plasma channel 141. In one or more embodiments, separators may be positioned between portions of adjacent plates 142. In embodiments, the separators may include a boron nitride spacer (not shown) closest to the plasma channel 141, a Viton O-ring surrounding the boron nitride spacer, and a PVC or PEEK spacer surrounding the Viton O-ring. Brazed or diffusion-bonded metal-to-metal seals may be used as an alternative to the Viton O-ring to provide longer life in high-neutron environments.

[0018] 2B , the cathode housing 150 is configured to support a plurality of cathodes 151, as described above. The cathode housing 150 also includes a cathode target region 153 fluidly coupled to a target chamber 160, where a target gas contained therein resides. Each cathode 151 includes a cathode needle 152 extending from the cathode 151 into the cathode target region 153. The cathode 151 applies a voltage (e.g., a voltage in the range of 150 V to 250 V, such as 200 V) between multiple points within the cathode target region 153 via the cathode needle 152 to initiate and / or maintain heating and ionization of a portion of the target gas, thereby forming a viscous plasma 310. In some embodiments, the cathode 151 is voltaged to initiate and maintain the formation of the plasma 310. However, other methods of initiating the formation of the plasma 310 are contemplated, such as applying an initial voltage using one or more starting coils, such as Tesla coils. Although not shown, such a starting coil may be attached to one or more of the plates 142 of the plasma window 140. Additionally, in embodiments including a starting coil, the cathode 151 may further apply a voltage to maintain the plasma 310. The cathode target region 153 of the cathode housing 150 is fluidly coupled to the target chamber 160 by a gas inlet 154, with both the target chamber 160 and the cathode target region 153 operating at a significantly higher pressure than the anode 130 and the low-pressure chamber 120. The target chamber 160 and the cathode target region 153 may be pressurized, such as by a pumping system. It should be understood that in some embodiments, the cathode target region 153 is a portion of the target chamber 160, i.e., the portion of the target chamber 160 closest to the cathode needle 152.

[0019] The transmission of the high-energy ion beam from the anode 130 through the plasma window 140 to the cathode housing 150 will now be described with reference to FIG. 3, which is a cross-sectional view of the anode 130, plasma window 140, and cathode housing 150. As mentioned above, the anode 130, in embodiments, can be an anode plate including a nozzle 131 fluidly connected to the low-pressure chamber 120 (not shown in FIG. 3) and a channel 132 fluidly connected to the nozzle 131. The plasma window 140 shown in FIG. 3 includes five adjacent plates 142 with circular openings coaxially aligned to form a plasma channel 141. The plasma channel 141 is fluidly connected to the channel 132 of the anode 130 and a cathode target region 153 of the cathode housing 150. A target gas is introduced into the cathode target region 153, and a plasma 310 is generated in the cathode needle 152 (or one or more starting coils), which fills the plasma channel 141 and extends into the channel 132 of the anode 130. By filling the plasma channel 141 with the plasma 310, a pressure barrier is formed between the cathode housing 150 and the anode 130. Meanwhile, an ion beam from the ion accelerator (shown in FIG. 1 ) can be transmitted through the plasma 310. Thus, a pressure differential between the high-pressure side of the beam accelerator system 100 and the low-pressure side of the beam accelerator system 100 can be maintained while transmitting a high-energy ion beam through the beam accelerator system 100.

[0020] As discussed above, the plasma window 140 disclosed and described herein is effective in maintaining a pressure differential in the beam accelerator system 100, thereby significantly reducing the costs (both capital and operational) and footprint associated with pumping systems required in beam accelerator systems 100 that do not utilize one or more plasma windows 140. However, once the plasma channel 141 fills with plasma 310, cooling the plasma window 140 becomes a challenge. In particular, it is conventional to use a constant power density across the plasma channel 141 regardless of the diameter of the plasma channel 141. However, as the diameter of the plasma channel 141 increases, the total power impinging on the walls of the plasma channel 141 increases, resulting in extremely high temperatures. Therefore, the plate 142 of the plasma window 140 can be designed to improve cooling of the plate 142 and the plasma channel 141. Such designs may incorporate cooling channels through the thickness t of the plate 142, where a cooling fluid, such as deionized water, is flowed through the cooling channels, thereby extracting heat from portions of the plate 142 near the walls of the plasma channel 141 to the cooling fluid. Important considerations in cooling channel design include the associated pressure drop across the cooling channels and the cooling capacity of the cooling fluid, e.g., the maximum temperature of the walls of the plasma channel 141 under a given set of operating conditions. The present disclosure provides impingement cooling channel designs for the plate 142 that achieve good cooling of the plasma channel 141 with an acceptable pressure drop across the cooling channels.

[0021] A front view of a four-way jet impingement cooling channel design of plate 142 used in plasma window 140 is now described with reference to FIG. 4A . Plate 142 has a circular opening 410 positioned near the geometric center of plate 142. The majority of plate 142 is constructed from a thermally conductive metal such as copper, silver, molybdenum, tungsten, or related alloys. In an embodiment, plate 142 is constructed from copper. Additionally, the plate may be a combination of materials. For example, plate 142 may be comprised of a generally copper body with a tungsten layer near plasma channel 141 (i.e., at the walls of opening 410).

[0022] As described above, when multiple plates 142 are placed adjacent to one another, the openings 410 in each plate 142 align to form a plasma channel in the plasma window, and the plasma 310 fills the plasma channel. The diameter of the openings 410 in each plate 142 is then approximately the size of the ion beam transmitted through the plasma channel. In embodiments, the openings 410 have diameters between 1.0 mm and 10.0 mm, such as between 2.0 mm and 8.0 mm, between 3.0 mm and 7.0 mm, or between 4.0 mm and 6.0 mm. In some embodiments, the plasma window may have a variable aperture size that can be tailored to more closely match the characteristics of the ion beam. The diameter of high-energy ion beams (and potentially high-energy electron beams) generated in beam accelerator systems is orders of magnitude larger than the sub-millimeter diameter of electron beams used in typical low-power electron beam (e-beam) systems. This allows smaller aperture diameters to be used in typical e-beam and low energy precision ion beam systems than in beam accelerator systems that produce high energy ion beams, and as noted above, the larger the aperture diameter used, the more total power and heat will be transferred to the aperture walls. That is, plates 142 used in plasma windows of high energy ion beam accelerator systems have entirely different cooling requirements than their counterparts used in e-beam and low energy precision ion beam systems.

[0023] As described above, the high-energy ion beam has approximately the same diameter as the plasma channel, which in turn causes the ion beam to have approximately the same diameter as the opening 410 in the plate 142. This can lead to excessive heat loads on the plate 142, particularly around the opening 410, even when the plate 142 is formed using a thermally conductive metal such as copper. Furthermore, portions of the plasma filling the plasma channel may contact the inner walls of the opening 410. Thermally conductive metals traditionally used in the industry, such as copper, may not be able to withstand the temperatures generated by contact with or even proximity to the plasma. Therefore, in one or more embodiments disclosed and described herein, a ring of a refractory metal 411, such as tungsten or molybdenum, may be used to form the inner wall of the opening 410 and thereby the inner wall of the plasma channel. 5, a thermally conductive metal plate 143 (e.g., a plate made of copper) may be integrally formed around a cylindrical slug of refractory metal 411a, such as by molding a liquidus thermally conductive metal around the cylindrical slug of refractory metal 411a. Once the thermally conductive metal plate 143 is formed, the cylindrical slug 411a may be machined to form an opening 410 with an inner surface of the refractory metal 411a.

[0024] 4A, as mentioned above, when the plasma fills the plasma channel, a large amount of heat is generated, which creates a large thermal load on the plate 142 around the opening 410. This thermal load can result in poor performance or even failure of the plate 142.

[0025] 4B shows a side view of plate 142 including only openings 410 (i.e., without any cooling channel design). Plate 142 has a first surface 142a and a second surface 142b that is generally parallel to first surface 142a. A thickness t of plate 142 is defined by the distance between first surface 142a and second surface 142b. Edge 142c extends from first surface 142a to second surface 142b and forms the periphery of plate 142. Thus, edge 142c is present on all four sides of plate 142 shown in FIG. 4A.

[0026] The four-way jet impingement cooling channel design will now be described in more detail with continued reference to FIG. 4A . While the plate 142 shown in FIG. 4A is generally square-shaped, any suitable shape may be used. The plate 142 includes a central wall 450 surrounding the opening 410. In some embodiments, the central wall 450 is annular-shaped such that the outer-facing surface of the central wall 450 is equidistant from the opening 410 at all circumferential locations. However, it should be understood that embodiments including a polygonal-shaped central wall 450, such as a rectilinear-shaped central wall 450, are contemplated. In embodiments in which the refractory metal 411 forms the inner wall of the opening 410, the central wall 450 comprises the refractory metal 411. The central wall 450 includes an inner-facing surface 451 and an outer-facing surface 452. The inner-facing surface 451 of the central wall 450 may also define a wall portion of the opening 410. In embodiments in which central wall 450 is annular, inner facing surface 451 may be an inner annular surface and outer facing surface 452 may be an outer annular surface. The width of central wall 450 may be defined by the radial distance between inner facing surface 451 and outer facing surface 452. In embodiments, the width of central wall 450 is between 4 mm and 16 mm, between 6 mm and 14 mm, or between 8 mm and 12 mm. In one embodiment, the width of central wall 450 is 9.525 mm.

[0027] Around the central wall 450 is a cooling chamber 460. The cooling chamber 460 may have an inner surface, e.g., an inner annular surface 461, and an outer surface, e.g., an outer annular surface 462. The width of the cooling chamber 460 may be defined by the radial distance between the inner annular surface 461 and the outer annular surface 462. The radius of the outer annular surface 462 of the cooling chamber 460 is greater than the radius of the inner annular surface 461 of the cooling chamber 460. The inner annular surface 461 of the cooling chamber 460 may define the outer annular surface of the central wall 450 (e.g., if the central wall 450 is annular-shaped). In embodiments, the width of the cooling chamber 460 is between 2 mm and 16 mm, between 4 mm and 14 mm, or between 6 mm and 12 mm.

[0028] The central wall 450 and the opening 410 extend from the first surface 142a to the second surface 142b. Meanwhile, the cooling chamber 460 is bounded by the first surface 142a and the second surface 142b. In other words, the cooling chamber 460 extends through the thickness t of the plate 142.

[0029] First impingement channel 421, second impingement channel 422, third impingement channel 423, and fourth impingement channel 424 enter plate 142 through edge 142c of plate 142 between first face 142a and second face 142b and extend toward opening 410. First impingement channel 421, second impingement channel 422, third impingement channel 423, and fourth impingement channel 424 enter plate 142 on different sides of plate 142. Referring to FIG. 4A , first impingement channel 421 enters plate 142 from the left side, second impingement channel 422 enters from the top side of the plate, third impingement channel 423 enters from the right side of the plate, and fourth impingement channel enters from the bottom side of the plate. Similar to cooling chamber 460, each of first impingement channel 421, second impingement channel 422, third impingement channel 423, and fourth impingement channel 424 is bounded by first face 142a and second face 142b. That is, each of first impingement channel 421, second impingement channel 422, third impingement channel 423, and fourth impingement channel 424 extends toward opening 410 in a manner generally parallel to first face 142a and second face 142b and extends through thickness t of plate 142.

[0030] The first impingement channel 421 enters the plate 142 from a first side of the plate 142 (i.e., the left side, in the -x direction) at an inlet 421 a of the first impingement channel 421 and terminates at an outlet 421 b within the cooling chamber 460. The second impingement channel 422 enters the plate 142 from a second side of the plate 142 (i.e., the top side, in the +y direction) at an inlet 422 a of the second impingement channel 422 and terminates at an outlet 422 b within the cooling chamber 460. The third impingement channel 423 enters the plate 142 from a third side of the plate 142 (i.e., the right side, in the +x direction) at an inlet 423 a of the third impingement channel 423 and terminates at an outlet 423 b within the cooling chamber 460. The fourth impingement channel 424 enters the plate 142 from a fourth side (i.e., the bottom side, in the -y direction) of the plate 142 at a fourth impingement channel 424 inlet 424a and terminates at an outlet 424b within the cooling chamber 460. The portions of the first impingement channel 421, the second impingement channel 422, the third impingement channel 423, and the fourth impingement channel 424 that extend into the cooling chamber 460 are referred to as a first impingement channel wall 421c, a second impingement channel wall 422c, a third impingement channel wall 423c, and a fourth impingement channel wall 424c, respectively. In one embodiment, each of the first impingement channel 421 , the second impingement channel 422 , the third impingement channel 423 and the fourth impingement channel 424 terminates at an outer annular surface 462 of the cooling chamber 460 .

[0031] First impingement channel 421, second impingement channel 422, third impingement channel 423, and fourth impingement channel 424 may terminate within cooling chamber 460 at an equal distance from inner annular surface 461 of cooling chamber 460. This distance is referred to herein as an impingement separation gap, which may be between 2 mm and 8 mm, between 3 mm and 7 mm, or between 4 mm and 6 mm.

[0032] In the embodiment, the longitudinal axes of the first impingement channel 421 and the third impingement channel 423 are aligned with a centerline 430 that bisects the cross-section of the opening 410 horizontally (i.e., in the x-direction), and the longitudinal axes of the second impingement channel 422 and the fourth impingement channel 424 are aligned with a centerline 440 that bisects the cross-section of the opening 410 vertically (i.e., in the y-direction). This allows the first impingement channel 421 and the third impingement channel 423 to be approximately perpendicular to the second impingement channel 422 and the fourth impingement channel 424. Thus, the first impingement channel 421, the second impingement channel 422, the third impingement channel 423, and the fourth impingement channel 424 are radially arranged and separated by 90 degrees from one another.

[0033] 4A further includes a first return channel 425, a second return channel 426, a third return channel 427, and a fourth return channel 428, each of which enters the plate 142 at an edge 142c of the plate 142 between the first and second faces 142a, 142b and extends toward the opening 410. Similar to the cooling chamber 460, each of the first return channel 425, the second return channel 426, the third return channel 427, and the fourth return channel 428 is bounded by the first and second faces 142a, 142b. That is, each of the first return channel 425, the second return channel 426, the third return channel 427 and the fourth return channel 428 extends toward the opening 410 in a manner generally parallel to the first surface 142a and the second surface 142b and extends through the thickness t of the plate 142.

[0034] The first return channel 425 enters the plate 142 at an outlet 425b positioned in the upper left corner of the plate, extends toward the opening 410 at an angle of approximately 45° relative to both the first impingement channel 421 and the second impingement channel 422, and terminates at an inlet 425a in the outer annular wall (outer annular surface) 462 of the cooling chamber 460. The second return channel 426 enters the plate 142 at an outlet 426b positioned in the upper right corner of the plate, extends toward the opening 410 at an angle of approximately 45° relative to both the second impingement channel 422 and the third impingement channel 423, and terminates at an inlet 426a in the outer annular wall 462 of the cooling chamber 460. The third return channel 427 enters the plate 142 at an outlet 427b positioned in the lower right corner of the plate, extends toward the opening 410 at an angle of approximately 45° relative to both the third impingement channel 423 and the fourth impingement channel 424, and terminates at an inlet 427a in the outer annular wall 462 of the cooling chamber 460. The fourth return channel 428 enters the plate 142 at an outlet 428b positioned in the lower left corner of the plate, extends toward the opening 410 at an angle of approximately 45° relative to both the fourth impingement channel 424 and the first impingement channel 421, and terminates at an inlet 428a in the outer annular wall 462 of the cooling chamber 460. This allows the first return channel 425 and the third return channel 427 to be approximately perpendicular to the second return channel 426 and the fourth return channel 428. Thus, the first return channel 425, the second return channel 426, the third return channel 427, and the fourth return channel 428 are radially arranged and separated by 90° from one another. Furthermore, each of the first impingement channel 421, the second impingement channel 422, the third impingement channel 423, and the fourth impingement channel 424 is radially adjacent to two return channels, and each of the first return channel 425, the second return channel 426, the third return channel 427, and the fourth return channel 428 is radially adjacent to two impingement channels.

[0035] It should be understood that in some embodiments, plate 142 is not square, and the angular separation of the impingement and return channels may be varied accordingly. For example, in an embodiment with a hexagonal plate, three impingement channels may be separated by 120° from one another, and three return channels may be separated by 120° from one another and arranged in an alternating manner with the three impingement channels. In such an embodiment, each of the three impingement channels would be radially adjacent to two return channels and separated from each of the two adjacent return channels by an angle of approximately 60°. Similarly, each of the three return channels would be radially adjacent to two impingement channels and separated from each of the two adjacent impingement channels by an angle of approximately 60°.

[0036] The operation of the four-way jet impingement cooling channel design shown in FIG. 4A will now be described in more detail. As described above, the walls of the aperture (i.e., the inner facing surface of the center wall) are exposed to the plasma that fills the plasma channel and experiences a significant thermal load. The center wall 450 thermally couples the walls of the aperture (i.e., the inner facing surface 451 of the center wall) to the inner annular surface 461 of the cooling chamber 460, which acts as an impingement target for jets of cooling fluid issuing from the first impingement channel 421, the second impingement channel 422, the third impingement channel 423, and the fourth impingement channel 424. During operation, cooling fluid is directed from each impingement channel in the form of jets that impinge on the inner annular surface 461 of the cooling chamber 460, which is thermally coupled to the walls of the aperture via the center wall 450. This causes the heated cooling fluid to eject from the impingement channels, removing heat from the inner annular surface 461 of the cooling chamber 460, and thereby removing heat from the walls of the opening, for example, if a plasma is present in the plasma channel. After impinging on the inner annular surface 461 of the cooling chamber 460, the heated cooling fluid exits the cooling chamber 460 through the first return channel 425, the second return channel 426, the third return channel 427, and the fourth return channel 428.

[0037] 4A , each of the first impingement channel wall 421c, the second impingement channel wall 422c, the third impingement channel wall 423c, and the fourth impingement channel wall 424c extends into the cooling chamber 460 and terminates at a point offset from the inner annular surface 461 of the cooling chamber 460. The first impingement channel wall 421c, the second impingement channel wall 422c, the third impingement channel wall 423c, and the fourth impingement channel wall 424c may help to direct a jet of cooling fluid toward the inner annular surface 461 of the cooling chamber 460. By focusing the cooling fluid jet directly onto the central wall 450, which acts as a heat sink between the opening wall and the cooling chamber 460, the impingement cooling channel design forms a thin boundary layer at the inner annular surface 461 of the cooling chamber 460, which leads to a high heat transfer coefficient between the cooling fluid and the inner annular surface 461 of the cooling chamber 460.

[0038] Various ratios of feature sizes in the impingement channel cooling design can be controlled to optimize cooling capacity while maintaining an acceptable pressure drop across the impingement channel cooling design. For example, the ratio of the impingement separation gap to the width of the center wall 450 can be 0.25 to 2.0, 0.5 to 1.5, or 0.75 to 1.25. The ratio of the width of the cooling chamber 460 to the width of the center wall 450 can be 1.0 to 4.0, 1.5 to 3.5, or 2.0 to 3.0. The width of the cooling chamber 460 can be less than the width of the center wall 450.

[0039] In some embodiments, plate 142 can be one piece without seams or welding artifacts. By machining the cooling channels through the thickness t of plate 142, the integrity of plate 142 is not compromised by seams or welds traditionally present in plasma window plates, which can introduce weak points in plate 142.

[0040] According to one or more embodiments, the impingement and return channels have circular cross sections with diameters sized according to the desired cooling fluid flow rate. In other embodiments, the impingement and return channels may have elliptical, square, rectangular, pentagonal, hexagonal, or octagonal cross sections. Of course, the cross-sectional dimensions, such as the diameters, of the impingement and return channels are limited by the thickness t of the plate 142.

[0041] 4A includes four impingement channels and four return channels, it should be understood that more or less impingement and return channels may be employed. For example, in some embodiments, the impingement cooling channel design includes two impingement channels and two return channels, three impingement channels and three return channels, five impingement channels and five return channels, or six impingement channels and six return channels.

[0042] In any of the embodiments disclosed and described herein, the impingement and return channels may have a cross-sectional diameter of 0.5 mm to 5.0 mm, 1.0 mm to 5.0 mm, 2.5 mm to 5.0 mm, 4.0 mm to 5.0 mm, 0.5 mm to 3.0 mm, 1.0 mm to 3.0 mm, or 0.5 mm to 2.0 mm.

[0043] It should be understood that the plasma window 140 may be cooled using any of the embodiments described herein. In practice, operation of the beam accelerator system 100 may include generating a plasma 310 within the plasma channel 141. The plasma 310 may be generated by applying a voltage to a target gas (contained in the target chamber 160 and the cathode target region 153, which may comprise deuterium, tritium, argon, or helium), thereby heating and ionizing a portion of the target gas to form the plasma 310. In some embodiments, the input voltage is applied by the cathode 151. In other embodiments, the input voltage is applied by one or more starting coils, such as a Tesla coil, which may be attached to one or more of the plates 142. The method then includes directing the ion beam 111 generated by the ion accelerator 110 from the low-pressure chamber 120 through the plasma 310 disposed within the plasma channel 141 of the plasma window 140 and into the target chamber 160, where the target gas is contained. In the target chamber 160, the ion beam 111 may interact with the target gas to generate neutrons via a nuclear fusion reaction. The method also includes cooling the plasma window 140, specifically the plate 142 of the plasma window 140, which is heated by the plasma 310 in the plasma channel 141. As described above with respect to Figures 4A and 4B, the plate 142 may be cooled by directing a cooling fluid through one or more impingement channels 421-424 such that the cooling fluid impinges on the central wall 450 and transfers heat from the central wall 450 to the cooling fluid, which then flows into one or more return channels 425-428 as a heated cooling fluid.

[0044] As used herein, the terms "substantially," "about," and the like refer to the subsequently recited characteristic or measurement within normal manufacturing tolerances and imperfections in the relevant art.

[0045] According to a first aspect of the present disclosure, a beam accelerator system includes an ion accelerator for generating an ion beam, a low-pressure chamber, an anode adjacent to and fluidly connected to the low-pressure chamber, a plasma window adjacent to and fluidly connected to the anode, and a cathode housing adjacent to and fluidly connected to the plasma window, wherein the plasma window includes a plurality of cooling plates, each cooling plate including an opening aligned with an opening in one or more adjacent cooling plates to form a plasma channel, wherein one or more cooling plates of the plurality of cooling plates include a central wall surrounding the opening, a cooling chamber surrounding the central wall, one or more impingement channels entering the cooling plate from an outer edge thereof and extending toward the opening to the cooling chamber, and one or more return channels entering the cooling plate from the outer edge thereof and extending toward the opening to the cooling chamber, wherein each of the one or more impingement channels is configured to provide an inlet path for a cooling fluid to flow into the cooling chamber, and each of the one or more return channels is configured to provide an outlet path for a heated fluid to flow out of the cooling chamber.

[0046] A second embodiment can include the first embodiment, wherein the aperture is positioned at the center of each of the plurality of cooling plates and extends through a thickness of each of the plurality of cooling plates.

[0047] A third aspect may include the first or second aspect, wherein each of the one or more impingement channels comprises an impingement channel wall that extends into and terminates in the cooling chamber.

[0048] A fourth aspect may include any of the preceding aspects, wherein the central wall has a ring shape, the cooling chamber has an inner annular surface and an outer annular surface, the inner annular surface of the cooling chamber defining the outer annular surface of the central wall, and each of the one or more return channels terminates at the outer annular surface of the cooling chamber.

[0049] A fifth aspect may include the fourth aspect, wherein the cooling chamber has a width defined by a radial distance between an inner annular surface of the cooling chamber and an outer annular surface of the cooling chamber, and the width of the cooling chamber is between 2 mm and 16 mm.

[0050] A sixth aspect may include the fourth aspect, wherein the cooling chamber has a width defined by a radial distance between an inner annular surface of the cooling chamber and an outer annular surface of the cooling chamber, the central wall has a width defined by the inner annular surface, the outer annular surface, and the radial distance between the inner annular surface of the central wall and the outer annular surface of the central wall, and a ratio of the width of the cooling chamber to the width of the central wall is between 1.0 and 4.0.

[0051] A seventh aspect may include any of the preceding aspects, wherein each of the one or more impingement channels and each of the one or more return channels are radially arranged around the opening and in an alternating manner.

[0052] An eighth aspect may include any of the first to sixth aspects, wherein the one or more impingement channels comprise four radially arranged impingement channels separated by 90° from one another, and the one or more return channels comprise four radially arranged return channels separated by 90° from one another, each of the four impingement channels being radially adjacent to two return channels, each of the four return channels being radially adjacent to two impingement channels, and each of the four impingement channels being radially spaced 45° from an adjacent return channel.

[0053] A ninth aspect may include any of the preceding aspects, wherein one or more cooling plates in the plurality of cooling plates is a monolithic plate.

[0054] A tenth aspect may include any of the preceding aspects, wherein the plurality of cooling plates are formed from a thermally conductive material selected from the group consisting of copper, silver, aluminum, and tungsten.

[0055] An eleventh aspect may include any of the preceding aspects, wherein the inner wall of the opening is formed from a refractory material selected from tungsten or molybdenum.

[0056] A twelfth aspect may include any of the first to third aspects, the fifth aspect, or any of the seventh to eleventh aspects, wherein the central wall is ring-shaped and has an inner annular surface, an outer annular surface, and a width defined by a radial distance between the inner annular surface of the central wall and the outer annular surface of the central wall, and the width of the central wall is between 4 mm and 16 mm.

[0057] A thirteenth aspect may include the fourth aspect, wherein the central wall has an inner annular surface, an outer annular surface, and a width defined by a radial distance between the inner annular surface of the central wall and the outer annular surface of the central wall, and the width of the central wall is between 4 mm and 16 mm.

[0058] A fourteenth aspect may include the sixth aspect, wherein the width of the central wall is 4 mm to 16 mm.

[0059] A fifteenth aspect may include any of the first to third aspects, the fifth aspect, or any of the seventh to eleventh aspects, and further includes an impingement separation gap defined by a radial distance between an end point of each of the one or more impingement channels in the cooling chamber and an inner annular surface of the cooling chamber, wherein the central wall is ring-shaped and has an inner annular surface, an outer annular surface, and a width defined by the radial distance between the inner annular surface of the central wall and the outer annular surface of the central wall, and wherein a ratio of the impingement separation gap to the width ratio of the central wall is between 0.25 and 2.0.

[0060] A sixteenth aspect may include the fourth aspect, further comprising an impingement separation gap defined by a radial distance between an end point of each of the one or more impingement channels in the cooling chamber and an inner annular surface of the cooling chamber, wherein the center wall has an inner annular surface, an outer annular surface, and a width defined by the radial distance between the inner annular surface of the center wall and the outer annular surface of the center wall, and wherein a ratio of the impingement separation gap to the width of the center wall is between 0.25 and 2.0.

[0061] A seventeenth aspect may include any one of the sixth or twelfth to fourteenth aspects, further comprising an impingement separation gap defined by a radial distance between an end point of each of the one or more impingement channels in the cooling chamber and an inner annular surface of the cooling chamber, wherein a ratio of the impingement separation gap to a width of the center wall is between 0.25 and 2.0.

[0062] An eighteenth aspect may include any one of the first to fourteenth aspects, further comprising an impingement separation gap defined by a radial distance between an end point of each of the one or more impingement channels in the cooling chamber and an inner annular surface of the cooling chamber, the impingement separation gap being between 2 mm and 8 mm.

[0063] A nineteenth aspect may include any one of the fourteenth to seventeenth aspects, wherein the impingement separation gap is between 2 mm and 8 mm.

[0064] According to a twentieth aspect of the present disclosure, a method comprises generating a plasma in a plasma channel of a plasma window, the plasma window being positioned between and fluidly coupled to an anode and a cathode housing, a plurality of cathodes housed in the cathode housing, the plasma window comprising a plurality of cooling plates, each cooling plate having an opening aligned with the openings of one or more adjacent cooling plates to form a plasma channel, one or more cooling plates of the plurality of cooling plates having a central wall surrounding the opening, a cooling chamber surrounding the central wall, and a cooling plate entering the cooling plate from an outer edge of the cooling plate and extending toward the opening and out of the cooling chamber. and one or more impingement channels extending to the cooling chamber, and one or more return channels entering the cooling plate from an outer edge of the cooling plate and extending toward the opening to the cooling chamber, the method further comprising: directing an ion beam generated by the ion accelerator from the low-pressure chamber, through a plasma disposed in a plasma channel of the plasma window, and into a target chamber containing a target gas; and directing a cooling fluid through the one or more impingement channels such that the cooling fluid impinges against the central wall and transfers heat from the central wall to the cooling fluid, and thereafter flows into the one or more return channels as a heated cooling fluid.

[0065] A 21st aspect may include the 20th aspect, wherein generating the plasma in the plasma channel comprises applying an input voltage to the target gas to heat and ionize a portion of the target gas to form the plasma.

[0066] A twenty-second aspect may include the twentieth or twenty-first aspect, wherein the ion beam interacts with a target gas in the target chamber to generate neutrons through a nuclear fusion reaction.

[0067] A 23rd aspect may include any one of the 20th to 22nd aspects, wherein the central wall has a ring shape, the cooling chamber has an inner annular surface and an outer annular surface, the inner annular surface of the cooling chamber defining the outer annular surface of the central wall, and each of the one return channels terminates in the outer annular surface of the cooling chamber.

[0068] A twenty-fourth aspect may include any one of the twentieth to twenty-third aspects, wherein each of the one or more impingement channels and each of the one or more return channels are radially arranged around the opening and alternate in an alternating manner.

[0069] A 25th aspect may include any one of the 20th to 24th aspects, wherein the plurality of cooling plates are formed from a thermally conductive material selected from the group consisting of copper, silver, aluminum, and tungsten, and the inner wall of the opening is formed from a refractory material selected from tungsten or molybdenum. [Example]

[0070] The embodiments will be further clarified by the following examples.

[0071] The examples provided below were modeled using COMSOL software (version 6.0).

[0072] Example 1 A plate with the four-way jet impingement cooling channel design shown in Figure 4A was modeled, with the aperture diameter set to 10 mm and aperture power set to 1 kW / cm. 2 The cooling channel width was set to 3 mm, the center wall width was set to 9.525 mm, and the cooling fluid was water with an inlet temperature of 20°C.

[0073] FIG. 6A shows the results of a simulation of the four-way jet impingement channel design performed with the above parameters.

[0074] The graph in Figure 6A shows the temperature (°C) on the left y-axis against the cooling water flow rate (gal / min) on the x-axis for maximum opening temperature and maximum cooling channel temperature. The graph in Figure 6A shows the pressure drop (psi) in the cooling channel on the right y-axis against the cooling water flow rate (gal / min) on the x-axis. As shown in Figure 6A, the pressure drop begins to increase rapidly at flow rates between 2.5 gal / min and 3.0 gal / min, while the opening temperature and cooling channel temperature plateau near flow rates between 2.5 gal / min and 3.0 gal / min.

[0075] Comparative Example 1 A plate with a cooling channel design consisting of two circular parallel cooling channels, one on each side of the aperture, was modeled, and the aperture diameter was set to 10 mm and the aperture power was set to 1 kW / cm 2 The cooling channel diameter was set to 3 mm, the cooling channels were offset from the opening by 9.525 mm, and the cooling fluid was water with an inlet temperature of 20° C. This comparative cooling channel design is referred to as the “two-channel cooling plate.”

[0076] FIG. 6B shows the results of a simulation of a two-channel cooling plate.

[0077] The graph in Figure 6B shows temperature (°C) on the left y-axis against cooling water flow rate (gal / min) on the x-axis for maximum opening temperature and maximum cooling channel temperature. The graph in Figure 6B shows pressure drop (psi) in the cooling channel on the right y-axis against cooling water flow rate (gal / min) on the x-axis.

[0078] 7A and 7B graphically illustrate the results of the above simulations, where the results for the four-way jet impingement cooling channel design are shown as "four-way jets" and the results for the two-channel cooling plate are shown as "circular."

[0079] Figure 7A graphs maximum opening temperature (°C) along the y-axis against flow rate (gal / min) along the x-axis, and Figure 7B graphs maximum cooling channel temperature along the y-axis against flow rate (gal / min) along the x-axis.

[0080] As can be seen in Figure 7A, the four-way jet impingement cooling channel design achieves lower maximum opening temperatures across a wide range of test flow rates for the cooling channel designs. As the flow rate increases from 1 gal / min to 3 gal / min, the cooling performance of the four-way jet impingement cooling channel increases rapidly relative to the two-channel cooled plate. Figure 7B shows a similar improvement in performance for the four-way jet impingement cooling channel design relative to the two-channel cooled plate. The four-way jet impingement cooling channel design exhibits lower maximum flow rate temperatures across a wide range of test flow rates.

[0081] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the specification cover modifications and variations of the various embodiments described herein, provided such modifications and variations come within the scope of the appended claims and their equivalents.

Claims

1. an ion accelerator for generating an ion beam; a low pressure chamber; an anode adjacent to and fluidly connected to the low-pressure chamber; a plasma window adjacent to and fluidly connected to the anode; a cathode housing adjacent to and fluidly connected to the plasma window; the plasma window comprises a plurality of cooling plates, each cooling plate having an opening aligned with an opening in one or more adjacent cooling plates to form a plasma channel; One or more cooling plates of the plurality of cooling plates include: a central wall surrounding the opening; a cooling chamber surrounding the central wall; one or more impingement channels extending from an outer edge of the cooling plate into the cooling plate toward the opening and into the cooling chamber; one or more return channels entering the cooling plate from the outer edge thereof and extending toward the opening to the cooling chamber; wherein each of the one or more impingement channels is configured to provide an inlet path for cooling fluid to enter the cooling chamber, and each of the one or more return channels is configured to provide an outlet path for heated fluid to exit the cooling chamber.

2. The beam accelerator system of claim 1 , wherein the aperture is positioned at the center of each of the plurality of cooling plates and extends through a thickness of each of the plurality of cooling plates.

3. The beam accelerator system of claim 1 , wherein each of the one or more impingement channels comprises an impingement channel wall that extends into and terminates within the cooling chamber.

4. the central wall has a ring shape; the cooling chamber having an inner annular surface and an outer annular surface; the inner annular surface of the cooling chamber defines an outer annular surface of the central wall; The beam accelerator system of claim 1 , wherein each of the one or more return channels terminates at the outer annular surface of the cooling chamber.

5. 5. The beam accelerator system of claim 4, wherein the cooling chamber has a width defined by a radial distance between the inner annular surface of the cooling chamber and the outer annular surface of the cooling chamber, and the width of the cooling chamber is between 2 mm and 16 mm.

6. the cooling chamber having a width defined by a radial distance between the inner annular surface of the cooling chamber and the outer annular surface of the cooling chamber; the central wall having an inner annular surface, an outer annular surface, and a width defined by a radial distance between the inner annular surface of the central wall and the outer annular surface of the central wall; 5. The beam accelerator system of claim 4, wherein the ratio of said width of said cooling chamber to said width of said central wall is between 1.0 and 4.

0.

7. The beam accelerator system of claim 1 , wherein each of the one or more impingement channels and each of the one or more return channels are radially arranged around the opening and in an alternating manner.

8. the one or more impingement channels comprise four radially arranged impingement channels separated by 90 degrees from one another; the one or more return channels comprise four radially arranged return channels separated by 90 degrees from one another; Each of the four impingement channels is radially adjacent to two return channels, and each of the four return channels is radially adjacent to two impingement channels; The beam accelerator system of claim 1 , wherein each of the four impingement channels is radially spaced 45° from an adjacent return channel.

9. The beam accelerator system of claim 1 , wherein the one or more cooling plates in the plurality of cooling plates are monolithic plates.

10. 10. The beam accelerator system of claim 1, wherein said plurality of cooling plates are formed from a thermally conductive material selected from the group consisting of copper, silver, aluminum, and tungsten.

11. 10. The beam accelerator system of claim 1, wherein the inner wall of the opening is formed from a refractory material selected from tungsten or molybdenum.

12. 2. The beam accelerator system of claim 1, wherein the central wall is ring-shaped and has an inner annular surface, an outer annular surface, and a width defined by a radial distance between the inner annular surface of the central wall and the outer annular surface of the central wall, and wherein the width of the central wall is between 4 mm and 16 mm.

13. an impingement separation gap defined by a radial distance between a termination point of each of the one or more impingement channels within the cooling chamber and an inner annular surface of the cooling chamber; the central wall is ring-shaped and has an inner annular surface, an outer annular surface, and a width defined by a radial distance between the inner annular surface of the central wall and the outer annular surface of the central wall; The beam accelerator system of claim 1 , wherein the ratio of the impingement separation gap to the width of the central wall is between 0.25 and 2.

0.

14. 10. The beam accelerator system of claim 1, further comprising an impingement separation gap defined by a radial distance between a termination point of each of the one or more impingement channels within the cooling chamber and an inner annular surface of the cooling chamber, the impingement separation gap being between 2 mm and 8 mm.

15. 1. A method comprising: generating a plasma in a plasma channel of the plasma window; the plasma window is positioned between an anode and a cathode housing and is fluidly coupled to the anode and the cathode housing; A plurality of cathodes are housed in the cathode housing; the plasma window comprises a plurality of cooling plates, each cooling plate having an opening aligned with an opening in one or more adjacent cooling plates to form the plasma channel; One or more cooling plates of the plurality of cooling plates include: a central wall surrounding the opening; a cooling chamber surrounding the central wall; one or more impingement channels extending from an outer edge of the cooling plate into the cooling plate toward the opening and into the cooling chamber; one or more return channels entering the cooling plate from the outer edge thereof and extending toward the opening to the cooling chamber; Equipped with The method further comprises: directing an ion beam generated by an ion accelerator from a low-pressure chamber, through the plasma disposed in the plasma channel of the plasma window, and into a target chamber containing a target gas; directing a cooling fluid through the one or more impingement channels such that the cooling fluid impinges against the center wall and transfers heat from the center wall to the cooling fluid before flowing into the one or more return channels as a heated cooling fluid; A method for providing

16. 16. The method of claim 15, wherein generating the plasma in the plasma channel comprises applying an input voltage to the target gas to heat and ionize a portion of the target gas to form the plasma.

17. The method of claim 15 , wherein the ion beam interacts with the target gas in the target chamber to produce neutrons through a nuclear fusion reaction.

18. the central wall has a ring shape; the cooling chamber having an inner annular surface and an outer annular surface; the inner annular surface of the cooling chamber defines an outer annular surface of the central wall; The method of claim 15 , wherein each of the one or more return channels terminates at the outer annular surface of the cooling chamber.

19. The method of claim 15 , wherein each of the one or more impingement channels and each of the one or more return channels are radially arranged around the opening and in an alternating manner.

20. the plurality of cooling plates are formed from a thermally conductive material selected from the group consisting of copper, silver, aluminum, and tungsten; 16. The method of claim 15, wherein the interior walls of the opening are formed from a refractory material selected from tungsten or molybdenum.

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