Cooling plate assembly for a plasma window positioned in a beam accelerator system

Abstract

A beam accelerator system operable to produce medical isotopes includes an ion accelerator for generating an ion beam, a low-pressure chamber, an anode adjacent to and fluidly connected with the low-pressure chamber, a plasma window adjacent to and fluidly connected with the anode, and a cathode housing adjacent to and fluidly connected with the plasma window. The plasma window comprises a plurality of plates, each plate having an opening aligned with the openings of one or more adjacent plates to form a plasma channel. One or more of the plurality of plates includes an integral plate having an opening and one or more cooling channels, the one or more cooling channels extending into the integral plate at a first side and extending out of the integral plate at a second side. The one or more cooling channels extend within a thickness of the integral plate.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Patent Application No. 17 / 951,975, filed September 23, 2022, which is incorporated herein by reference in its entirety.

[0002] (Statement Regarding Federally Sponsored Research or Development) This disclosure was made with government support under Grant No. DE-AR0001377 awarded by the U.S. Department of Energy. The government has certain rights in this invention.

[0003] The present disclosure relates generally to cooling plates for plasma window systems, and more particularly to plasma window systems used in beam accelerator systems such as, for example, gas target neutron generating systems. [Background technology]

[0004] Beam accelerator systems are used to generate medical 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 generation system, a high-energy ion beam is directed toward a gas target. The generation and transport of the high-energy ion beam to the target requires a large amount of energy, generating a large amount of heat.

[0005] Therefore, a need exists for beam accelerator system components, such as gas target neutron generating systems, that help reduce the cost and energy required to generate radioisotopes. Summary of the Invention

[0006] According to one embodiment, a beam accelerator system operable to produce medical isotopes comprises an ion accelerator for generating a high energy ion beam, a low pressure chamber, an anode fluidly connected adjacent to the low pressure chamber, a plasma window fluidly connected adjacent to the anode, and a cathode housing fluidly connected adjacent to the plasma window, wherein the plasma window comprises a plurality of plates, each plate having an opening aligned with the openings of one or more adjacent plates to form a plasma channel, wherein one or more plates of the plurality of plates comprise an integral plate having an opening and one or more cooling channels, the one or more cooling channels extending into the integral plate at a first side and extending out of the integral plate at a second side of the integral plate, the one or more cooling channels extending within a thickness of the integral plate.

[0007] According to another embodiment, a beam accelerator system operable to produce medical isotopes comprises an ion accelerator for generating a high energy 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, the plasma window comprising a plurality of plates, each plate comprising an opening aligned with an opening in one or more adjacent plates to form a plasma channel, one or more plates of the plurality of plates extending within a respective layer thickness of the one or more plates and interdigitating with one or more plates at a first edge of the one or more plates to form a second plasma channel. The cooling system includes a first cooling channel and a second cooling channel extending from one or more plates at two sides, wherein the first cooling channel fits into one or more plates at a first side of the one or more plates, extends adjacent to a first side of the opening, bends in a first direction to extend adjacent to a second side of the opening, bends in a second direction to extend from the one or more plates at the second side of the one or more plates, and the second cooling channel fits into one or more plates at a first side of the one or more plates, extends to a third side of the opening, bends in the first direction to extend adjacent to the third side of the opening, bends in a second direction to extend adjacent to a fourth side of the opening, and extends from the second side of the one or more plates.

[0008] According to another embodiment, a beam accelerator system operable to produce medical isotopes comprises an ion accelerator that generates a high energy 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 comprises a plurality of plates, each plate comprising an opening aligned with the openings in one or more adjacent plates to form a plasma channel, wherein one or more plates of the plurality of plates comprise a first cooling channel, a second cooling channel, and a third cooling channel extending within respective layer thicknesses of the one or more plates. a first cooling channel that fits into one or more plates at a first side of the one or more plates, extends to a first side of the opening, and branches into a second cooling channel and a third cooling channel, the second cooling channel extending in a first direction adjacent to the first side of the opening to a second side of the opening, bending in a second direction, extending adjacent to the second side of the opening, and extending out of the one or more plates at the second side of the one or more plates, and the third cooling channel extending in a third direction adjacent to the first side of the opening to a third side of the opening, bending in the second direction, extending adjacent to the third side of the opening, and extending out of the one or more plates at the second side of the one or more plates. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 illustrates a schematic diagram of a gas target neutron generation system according to an embodiment disclosed and described herein. [Figure 2A] FIG. 2A shows a schematic 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] FIG. 2B shows a cross-sectional schematic of a low-pressure chamber, anode, plasma window, cathode housing, and cathode according to embodiments disclosed and described herein. [Figure 3]FIG. 3 shows a schematic cross-section of an anode, plasma window, and cathode housing according to an embodiment disclosed and described herein. [Figure 4] FIG. 4 shows a schematic front view of a plate with two parallel cooling channels according to an embodiment disclosed and described herein. [Figure 5] FIG. 5 shows a schematic front view of a plate with a refractory metal slug according to an embodiment disclosed and described herein. [Figure 6] FIG. 6 shows a schematic top view of a plate with two parallel cooling channels according to embodiments disclosed and described herein. [Figure 7] FIG. 7 shows a schematic front view of a plate with an L-shaped cooling channel design according to an embodiment disclosed and described herein. [Figure 8A] FIG. 8A schematically illustrates a front view of a plate with a U-shaped cooling channel design according to an embodiment disclosed and described herein. [Figure 8B] FIG. 8B schematically illustrates a front view of a plate with an inverted U-shaped cooling channel design according to an embodiment disclosed and described herein. [Figure 9] FIG. 9 shows a schematic front view of a plate with an O-shaped cooling channel design according to an embodiment disclosed and described herein. [Figure 10A] FIG. 10A graphically illustrates temperature and pressure drop versus flow rate for a plate having two parallel cooling channels with smooth interiors according to embodiments disclosed and described herein. [Figure 10B] FIG. 10B graphically illustrates temperature and pressure drop versus flow rate for a plate having two parallel cooling channels with a spirally designed interior according to embodiments disclosed and described herein. [Figure 11] FIG. 11 graphically illustrates temperature and pressure drop versus flow rate for a plate having an L-shaped cooling channel design according to embodiments disclosed and described herein. [Figure 12]FIG. 12 graphically illustrates opening temperature versus flow rate for a plate with cooling channel designs according to embodiments disclosed and described herein. [Figure 13] FIG. 13 graphically illustrates cooling channel temperature versus flow rate for a plate with cooling channel designs according to embodiments disclosed and described herein. [Figure 14] FIG. 14 graphically illustrates cooling channel pressure drop versus flow rate for a plate with cooling channel designs according to embodiments disclosed and described herein. DETAILED DESCRIPTION OF THE INVENTION

[0010] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description, or may be learned by practicing the embodiments described herein, including the detailed description which follows, the claims, and the accompanying drawings.

[0011] It should be understood that both the foregoing general description and the following detailed description are intended to describe various embodiments and 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 detailed description, serve to explain the principles and operation of the claimed subject matter.

[0012] 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, and where possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts.

[0013] 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 and a high-pressure gas target chamber. The plasma window enables the system to accommodate increased gas target pressures, shorter target lengths, and increased currents passed through the target (e.g., target gas present in the target chamber). In this regard, beam accelerator systems constructed with plasma windows provide up to two orders of magnitude increase in available neutron flux compared to conventional beam accelerator systems.

[0014] 1, an embodiment of a beam accelerator system 100 operable to produce medical isotopes includes an ion accelerator 110 that generates a high energy ion beam 111 that is directed into a low pressure chamber 120. In an embodiment, the low pressure chamber is at or near a vacuum, e.g., 1 torr or less, 0.1 torr or less, 0.01 torr or less, 1×10 -3 below torr, 1×10 -5 below torr, 1×10 -6The beam accelerator system 100 is operated at a pressure of 100 psi (1000 psi) or less, such as at 100 psi (0.25 psi) or less. The anode 130 is positioned adjacent to and fluidly connected to the low-pressure chamber 120 and separated from the 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 a plurality of cathodes 151, which are described in more detail below. The beam accelerator system 100 also includes a target chamber 160 for housing 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 on the high-pressure side of the beam accelerator system 100 and the anode 130 is on the low-pressure side (e.g., vacuum side) of the beam accelerator system 100. Gases produced by the ion accelerator 110 and present in the low pressure chamber 120 do not migrate beyond the anode 130 into the plasma window 140 or into 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 Figure 1 is for illustrative purposes only and is not drawn to scale.

[0015] 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 a large and expensive pumping infrastructure to maintain the low pressure required for ions to be accelerated from ion accelerator 110. Target chamber 160 can operate at pressures greater than a million times that present in beamline 110, e.g., 30 torr or greater, 50 torr or greater, 100 torr or greater, 500 torr or greater, 1000 torr or greater, or any value within a range containing any two of these values ​​as endpoints. Larger ion beam sizes and higher ion beam currents require more pumping due to the conductance of the ion beam through the channel to the target. Therefore, the beam size, and therefore the system yield, is limited by the diameter of the channel to the target chamber.

[0016] The use of a plasma window 140 between the low-pressure anode 130 and the high-pressure cathode housing 150 allows for a large pressure reduction factor relative to conventional channels, facilitating the use of larger diameter and higher power ion beams. The pressure reduction also results in a reduction in total pumping costs due to a reduction in the conductance and pumping hardware required to maintain the pressure differential.

[0017] 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 is configured to support four cathodes, three cathodes, or two cathodes. In embodiments where the cathode housing 150 is configured to support four cathodes, the cathodes 151 may be positioned approximately 90° from 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 approximately 120° from each other, and in embodiments where the cathode housing 150 is configured to support two cathodes, the cathodes 151 may be positioned approximately 180° from each other.

[0018] 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 within the anode 130 operate to deliver an ion beam from the low-pressure side of the beam accelerator system 100 to 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.

[0019] 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 less 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 propagates 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 that can accommodate the transmission of the high-energy ion beam. The plates 142 of the plasma window 140, in embodiments, are electrically floating and cooled with a fluid, such as water, as 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, a separator may be positioned between portions of adjacent plates 142. In an embodiment, the separator 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 spacer surrounding the Viton O-ring.

[0020] 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 that is fluidly coupled to the target chamber 160 and within which a target gas contained in the target chamber 160 is also present. Each cathode 151 includes a cathode needle 152 that extends 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 applies a voltage to initiate and maintain the formation of the viscous plasma 310. However, other methods of initiating the formation of the viscous plasma 310 are contemplated, such as applying an initial voltage using one or more starting coils, such as Tesla coils. While not shown, such starting coils may be attached to one or more of the plates 142 of the plasma window 140. Additionally, in embodiments including starting coils, the cathode 151 may be further energized to maintain the viscous 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 region (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 region 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.

[0021] 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 having 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 viscous plasma 310 is generated in the cathode needle 152 (or in 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 viscous plasma 310, a pressure barrier is formed between the cathode housing 150 and the anode 130. However, an ion beam from the ion accelerator (shown in FIG. 1 ) can be transmitted through the viscous 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.

[0022] As discussed above, the plasma window 140 disclosed and described herein is effective in maintaining a pressure differential in the beam accelerator system 100, which can significantly reduce 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 viscous plasma 310, cooling the plasma window 140 becomes difficult. In particular, it is conventional to use a constant power density for 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 applied to the walls of the plasma channel 141 increases, resulting in significantly higher temperatures. Therefore, the plate 142 of the plasma window 140 may be designed to improve cooling of the plate 142 and the plasma channel 141. Such a design is described herein.

[0023] A front view of a plate 142 used in a plasma window 140 according to one or more embodiments is illustrated with reference to FIG. 4 . The plate 142 has a generally rectangular shape with a central opening 410 positioned near the geometric center of the plate 142. However, it should be understood that the shape of the plate may vary depending on the embodiment. The majority of the plate 142 is constructed from a thermally conductive metal, such as copper, silver, molybdenum, tungsten, or a related alloy. Additionally, the plate may be a combination of materials. For example, the plate may be generally copper with a tungsten layer near the arc. In an embodiment, the plate 142 is constructed from copper. As described above, when multiple plates 142 are positioned adjacent to one another, the openings 410 in each plate 142 align to form a plasma channel in the plasma window, and a viscous plasma fills the plasma channel. This allows the diameter of the opening 410 in each plate 142 to be approximately the size of the ion beam transmitted through the plasma channel. In embodiments, the aperture 410 has a diameter between 1.0 mm and 10.0 mm, such as a diameter between 2.0 mm and 8.0 mm, 3.0 mm and 7.0 mm, or 4.0 mm and 6.0 mm. In embodiments, the aperture diameter may vary along the plasma window to match the varying diameter of the plasma window. In such embodiments, the aperture diameter is larger at one end of the plasma window than at the opposite end of the plasma window. The diameter of the ion beam generated in embodiment beam accelerator systems is orders of magnitude larger than the sub-millimeter diameter of the electron beam used in e-beam systems. Thus, much smaller aperture diameters may be used in electron beam (e-beam) systems and high-precision low-current ion beams than in embodiment beam accelerator systems that generate high-current ion beams; as noted above, the larger the aperture diameter used, the more total power and heat will be transferred to the aperture walls. That is, the plate 142 used in the plasma window of embodiment ion beam accelerator systems has entirely different cooling requirements than components used in low-current e-beam and low-current ion beam systems.

[0024] As mentioned above, the high-energy ion beam has approximately the same diameter as the plasma channel, which causes the ion beam to have approximately the same diameter as the opening 410 in the plate 142. This can result in a large heat load on the plate 142, particularly around the opening 410, even when a thermally conductive metal such as copper is used to form the plate 142. Furthermore, portions of the viscous plasma filling the plasma channel may contact the inner walls of the opening 410. Thermally conductive metals conventionally used in the industry, such as copper, may not be able to withstand the temperatures caused by contact with or even proximity to the viscous plasma. Therefore, in one or more embodiments disclosed and described herein, a ring of 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 142a (such as a copper plate) may be integrally formed around a cylindrical slug of refractory metal 411a, such as by forming a liquid phase thermally conductive metal around the cylindrical slug of refractory metal 411a. Once the thermally conductive metal plate 142a is formed, the cylindrical slug 411a may be machined to form an opening 410 with an inner surface of the refractory metal 411a.

[0025] 4 , as described above, when a viscous plasma fills the plasma channel, a large amount of heat is generated, which generates a large thermal load on the plate 142 around the opening 410. This thermal load may result in poor performance or even failure of the plate 142. Therefore, cooling channels 421 and 422 may be provided in the plate 142 near the opening 410. A cooling fluid, such as deionized water, is flowed through the cooling channels 421 and 422 to extract heat from a portion of the plate 142 near the opening 410 to the cooling fluid. Each cooling channel 421 and 422 extends through the plate 142 such that the low-temperature cooling fluid enters the plate 142 at inlets 421 a and 422 a, respectively, positioned on a first side of the plate 142, and exits the plate 142 at outlets 421 b and 422 b, respectively, positioned on a second side of the plate 142. As shown in FIG. 4 , the first cooling channel 421 is positioned on a first side of the opening (i.e., the left side in the −x direction), the second cooling channel 422 is positioned on a second side of the opening 410 (i.e., the right side in the +x direction), and the first cooling channel 421 is generally parallel to the second cooling channel 422. As used herein, “substantially parallel” is used to mean parallel with acceptable manufacturing tolerances. In embodiments, it is desirable to position the first cooling channel 421 and the second cooling channel 422 as close to the opening 410 as possible without compromising the structural integrity of the plate 142 and the opening 410. Although FIG. 4 shows the first cooling channel 421 and the second cooling channel 422 equidistant from the opening 410, in embodiments, either the first cooling channel 421 or the second cooling channel 422 may be positioned closer to the opening 410 than the other cooling channel. Additionally, in accordance with one or more embodiments, the first cooling channel 421 does not have to be positioned parallel to the second cooling channel 422 .

[0026] The cooling channels 421 and 422 may be machined into the plate 142 by drilling, laser or water beam ablation, or the like. Referring to FIG. 6 , which shows a top view of the plate 142, the cooling channels are machined into the thickness t of the plate 142. FIG. 6 shows the inlet 421a of the first cooling channel and the inlet 422a of the second cooling channel extending adjacent to the opening 410 in the plate 142. By machining the cooling channels into the thickness of the plate 142, the integrity of the plate 142 is not compromised by seams or welds traditionally present in plasma window plates, which can result in weak points in the plate 142. A plate without seams or welds is referred to herein as a “solid plate.” As mentioned above, the plasma window in which the plate 142 is positioned experiences a large pressure differential as a result of the plasma window separating the high-pressure side of the beam accelerator system from the low-pressure side of the beam accelerator system. Additionally, the solid plate 142 experiences high thermal loads. Pressure differentials and thermal loads can cause any seams in the unitary plate 142 to fail. Thus, the plates of one or more embodiments disclosed and described herein may comprise unitary plates. It should be understood that use of the term "plate" in this disclosure can refer to unitary plates or non-unitary plates.

[0027] According to one or more embodiments, the cooling channels 421 and 422 have a circular cross-section (as shown in FIG. 6 ), with the diameter of the cooling channels 421 and 422 being sized according to the amount of cooling fluid throughput desired. In other embodiments, the cooling channels 421 and 422 may have an oval, square, rectangular, pentagonal, hexagonal, or octagonal cross-section. Of course, the cross-sectional dimensions, such as the diameter, of the cooling channels 421 and 422 are limited by the thickness t of the plate 142.

[0028] In embodiments, the interior surfaces of the cooling channels 421 and 422 may be individually smooth, allowing for a relatively laminar flow of cooling fluid from the inlets 421 a and 422 a, respectively, of the cooling channels 421 and 422 positioned on the first side of the plate 142 to the outlets 421 b and 422 b, respectively, of the cooling channels 421 and 422 positioned on the second side of the plate 142. However, in other embodiments, the interiors of the cooling channels 421 and 422 may have a helical design that results in a turbulent flow of cooling fluid from the inlets 421 a and 422 a, respectively, of the cooling channels 421 and 422 positioned on the first side of the plate 142 to the outlets 421 b and 422 b, respectively, of the cooling channels 421 and 422 positioned on the second side of the plate 142. The spiral design may be provided via a spiral-shaped insert present within the cooling channels 421 and 422, or by machining the cooling channels 421 and 422 to have an integral spiral design on their inner surfaces. The turbulent flow of cooling fluid through the cooling channels 421 and 422, provided by the spiral-designed interior of the cooling channels 421 and 422, aids in the transfer of heat from the opening 410 to the cooling fluid compared to cooling channels 421 and 422 with smooth inner surfaces. Meanwhile, cooling channels 421 and 422 with smooth inner surfaces are easier to fabricate and have a lower pressure drop across the cooling channels 421 and 422. The cooling effect is primarily provided by the cooling fluid flow rate and turbulence within the cooling channels 421 and 422. The higher the flow rate and the more turbulence within the cooling channels 421 and 422, the greater the cooling effect provided. Meanwhile, increased flow rate and turbulence within the cooling channels 421 and 422 results in a larger pressure drop. Thus, cooling effect and pressure drop are balanced to achieve the desired result.

[0029] Referring again to FIG. 4 , providing cooling channels 421 and 422 on opposite sides of opening 410 provides good cooling of the opening wall portion positioned directly between opening 410 and cooling channels 421 and 422. However, portions of the opening wall positioned along centerline 430 and not directly between opening 410 and cooling channels 421 and 422 may not be sufficiently cooled by the cooling channel design shown in FIG. 4 , even though the interiors of cooling channels 421 and 422 have a spiral design in one or more embodiments. That is, the farther the opening wall portion is from the cooling channels, the less cooling effect that portion of the opening wall receives. Accordingly, further embodiments of cooling channel designs that provide more uniform cooling of the opening wall portion are provided herein.

[0030] 7 is a front view of plate 142 having an L-shaped cooling channel design. Plate 142 includes opening 410 having an annular inner surface made of refractory metal 411, as described above. The embodiment of plate 142 as shown in FIG. 7 includes first cooling channel 721 and second cooling channel 722. Each of first cooling channel 721 and second cooling channel 722 has an "L" shape. First cooling channel 721 is positioned to the left of second cooling channel 722 (i.e., left in the -x direction).

[0031] At a first side (i.e., the lower side in the −y direction) of the plate 142 and at an outlet 721b of the first cooling channel 721, the first cooling channel 721 is located on a first side (i.e., the left side in the −x direction) of the opening 410 and extends upward (i.e., in the +y direction) within the plate 142 so that the first cooling channel 721 passes adjacent to the first side (i.e., the left side in the −x direction) of the opening 410. When the first cooling channel 721 extends past a second side (i.e., the upper side in the +y direction) of the opening, the first cooling channel 721 turns in the first direction (i.e., the right side in the +x direction) and extends along the second side (i.e., the upper side in the +y direction) of the opening 410. As the first cooling channel 721 extends to the fourth side of the opening 410 (i.e., to the right in the +x direction), the first cooling channel 721 turns in a second direction (i.e., upward in the +y direction) and extends toward the second end of the plate 142 (i.e., the top edge in the +y direction) to an inlet 721a of the first cooling channel 721. With the cooling channel design shown in the embodiment of Figure 7, the first cooling channel 721 provides cooling to the first side of the opening 410 (i.e., to the left in the -x direction) and to the second side of the opening 410 (i.e., the top side in the +y direction).

[0032] At the first side (i.e., the lower side in the −y direction) of the plate 142 and at the outlet 722b of the second cooling channel 722, the second cooling channel 722 is located between the center line 430 of the opening 410 and the first cooling channel 721. The second cooling channel 722 extends upward (i.e., in the +y direction) within the plate 142 toward a third side (i.e., the lower side in the −y direction) of the opening 410. When the second cooling channel 722 reaches the third side (i.e., the lower side in the −y direction) of the opening 410, it approaches the first side (i.e., the left side in the −x direction) of the opening 410 and turns in the first direction (i.e., the right side in the +x direction) to extend along the third side (i.e., the lower side in the −y direction) of the opening 410. As the second cooling channel 722 extends past the fourth side of the opening 410 (i.e., to the right in the +x direction), the second cooling channel 722 makes a turn in the plate 142 in a second direction (i.e., upward in the +y direction) and extends along the fourth side of the opening 410 (i.e., to the right in the +x direction) until the second cooling channel 722 reaches an inlet 722a of the second cooling channel 722. With the cooling channel design shown in the embodiment of Figure 7, the second cooling channel 722 provides cooling to the third side of the opening 410 (i.e., downward in the -y direction) and the fourth side of the opening 410 (i.e., to the right in the +x direction).

[0033] The cooling channel design of the embodiment shown in FIG. 7 provides cooling on four sides of the opening 410, as opposed to the embodiment shown in FIG. 4, which provides cooling on two sides of the opening.

[0034] 8A is a front view of plate 142 having a U-shaped cooling channel design. Plate 142 includes opening 410 having an annular inner surface made of refractory metal 411, as described above. The embodiment of plate 142 shown in FIG. 8A includes a first cooling channel 821 that branches into a second cooling channel 822 and a third cooling channel 823. The combination of first cooling channel 821, second cooling channel 822, and third cooling channel 823 forms a "U" shape.

[0035] The first cooling channel 821 fits into the plate 142 at a first side (i.e., the lower side in the -y direction) of the plate 142 and near an outlet 821b of the first cooling channel 821. In the embodiment, the longitudinal axis of the first cooling channel 821 is positioned about a center line 430 that bisects the cross section of the opening 410. The first cooling channel 821 extends upward (i.e., in the +y direction) within the plate 142 toward the opening 410. When the first cooling channel 821 reaches a first side (i.e., the lower side in the -y direction) of the opening 410, the first cooling channel 821 branches into a second cooling channel 822 and a third cooling channel 823. In the embodiment, each of the second cooling channel 822 and the third cooling channel 823 is approximately perpendicular to the first cooling channel 821.

[0036] The second cooling channel 822 extends horizontally in a first direction (i.e., to the left in the −x direction) along a first side (i.e., the lower side in the −y direction) of the opening 410 toward a second side (i.e., the left side in the −x direction) of the opening 410. As the second cooling channel 822 extends past the second side (i.e., the left side in the −x direction) of the opening 410, the second cooling channel 822 turns in a second direction (i.e., upward in the +y direction) and extends along the second side (i.e., the left side in the −x direction) of the opening 410 toward a second edge (i.e., the upper edge in the +y direction) of the plate 142 and toward the second cooling channel inlet 822 a.

[0037] The third cooling channel 823 extends in a third direction (i.e., to the right in the +x direction) along a first side (i.e., the lower side in the −y direction) of the opening 410 to the third side (i.e., the right side in the +x direction) of the opening 410. After the third cooling channel 823 extends past the third side (i.e., the right side in the +x direction) of the opening, the third cooling channel 823 turns in a second direction (i.e., upward in the +y direction) and extends along the third side (i.e., the right side in the +x direction) of the opening 410 toward the second edge (i.e., the upper edge in the +y direction) of the plate 142 and toward the second inlet 823 a.

[0038] 8A provides cooling to three sides of opening 410 (i.e., below opening 410, to the left of opening 410, and to the right of opening 410). In an embodiment, one or both plates 142 adjacent to a plate having the U-shaped cooling channel design of the embodiment shown in FIG. 8A may have the same U-shaped cooling channel design as the plate of the embodiment shown in FIG. 8A with two cooling channel inlets 822a and 823a positioned on the second side (i.e., the top side in the +y direction) of plate 142 and a single cooling channel outlet 821b positioned on the first side (i.e., the bottom side in the −y direction) of plate 142. On the other hand, in an embodiment, one or more plates 142 adjacent to a plate having the U-shaped cooling channel design of the embodiment shown in FIG. 8A may have an inverted U-shaped cooling channel design in which two cooling channel inlets 822a and 823a are positioned on a first side (i.e., the bottom side in the -y direction) of the plate 142 and a single cooling channel outlet 821b is positioned on a second side (i.e., the top side in the +y direction) of the plate 142.

[0039] The inverted U-shaped cooling channel design will now be described with reference to Figure 8B. Plate 142 includes opening 410 having an annular inner surface made of refractory metal 411, as described above. The embodiment of plate 142 shown in Figure 8B includes a first cooling channel 821 that branches into a second cooling channel 822 and a third cooling channel 823. The combination of first cooling channel 821, second cooling channel 822, and third cooling channel 823 forms an inverted "U" shape.

[0040] At the top side of the plate 142 (i.e., upward in the +y direction) and near the outlet 821b of the first cooling channel 821, the longitudinal axis of the first cooling channel 821 is positioned about a centerline 430 that bisects the cross section of the opening 410. The first cooling channel 821 extends downward (i.e., downward in the −y direction) within the plate 142 toward the opening 410. When the first cooling channel 821 reaches the fourth side of the opening 410 (i.e., upward in the +y direction), the first cooling channel 821 branches into a second cooling channel 822 and a third cooling channel 823.

[0041] The second cooling channel 822 extends in a first direction (i.e., left side in the −x direction) along a fourth side (i.e., upper side in the +y direction) of the opening 410 to a second side (i.e., left side in the −x direction) of the opening 410. As the second cooling channel 822 extends past the second side (i.e., left side in the −x direction) of the opening 410, the second cooling channel 822 turns in a second direction (i.e., downward in the −y direction) and extends along the second side (i.e., left side in the −x direction) of the opening 410 toward a second edge (i.e., lower side in the −y direction) of the plate 142 and toward an inlet 822 a of the second cooling channel 822.

[0042] The third cooling channel 823 extends in a third direction (i.e., to the right in the +x direction) along a fourth side (i.e., the upper side in the +y direction) of the opening 410 to the third side (i.e., the right side in the +x direction) of the opening 410. After the third cooling channel 823 extends past the third side (i.e., the right side in the +x direction) of the opening, the third cooling channel 823 bends in the second direction (i.e., downward in the −y direction) and extends along the third side (i.e., the right side in the +x direction) of the opening 410 toward the first side (i.e., the lower side in the −y direction) of the plate 142 and toward the third cooling channel inlet 823 a.

[0043] The inverted U-shaped cooling channel design of the embodiment shown in Figure 8B provides cooling to three sides of the openings 410 (i.e., below the openings 410, to the left of the openings 410, and to the right of the openings 410). This inverted U-shaped cooling channel design can be used to complement the U-shaped cooling channel design shown in Figure 8A, such that the upper sides of the openings 410 are cooled within various plates 142 and the lower sides of the openings 410 are cooled within various plates 142. For example, in one or more embodiments, plates having the U-shaped cooling channel design shown in Figure 8A may be alternated with plates having the inverted U-shaped cooling channel design shown in Figure 8B, such that the upper sides of the openings are cooled by every other plate and the lower sides of the openings are cooled by every other plate.

[0044] FIG. 9 is a front view of a plate 142 having an O-shaped cooling channel design. The plate 142 includes an opening 410 having an annular inner surface made of a refractory metal 411, as described above. The embodiment of the plate 142 shown in FIG. 9 includes a first portion of a first cooling channel 921 that branches into a second cooling channel 922 and a third cooling channel 923 on a first side of the opening 410. The second cooling channel 922 extends around the first portion of the opening 410, and the third cooling channel 923 extends around a second portion of the opening 410. The second cooling channel 922 and the third cooling channel 923 merge as a second portion of the first cooling channel 921 on a second side of the opening 410. The combination of the second cooling channel 922 and the third cooling channel 923 forms an annular "O" shaped cooling channel around the opening 410.

[0045] At a first side (i.e., the bottom side in the −y direction) of the plate 142 and at an outlet 921b of the first cooling channel 921, the longitudinal axis of the first cooling channel 921 is generally positioned about a centerline 430 that bisects the cross section of the opening 410. A first portion of the first cooling channel 921 extends upward (i.e., in the +y direction) within the plate 142 toward the opening 410. When the first cooling channel 921 reaches a first side (i.e., the bottom side in the −y direction) of the opening 410, the first cooling channel 921 branches into a second cooling channel 922 and a third cooling channel 923. The second cooling channel 922 extends in an annular shape adjacent to a second side (i.e., the left side in the −x direction) of the opening 410, following the shape of the opening 410. The third cooling channel 923 extends in a ring shape adjacent to the second side (i.e., the right side in the +x direction) of the opening 410 and follows the shape of the opening 410. Near the third side (i.e., the upper side in the +y direction) of the opening 410, the second cooling channel 922 and the third cooling channel 923 merge to form a second portion of the first cooling channel 921 that extends upward (i.e., in the +y direction) toward the second side (i.e., the upper side in the +y direction) of the plate 142 and the cooling channel inlet 921 a.

[0046] The O-shaped cooling channel design of the embodiment shown in FIG. 9 provides cooling on all sides of the opening 410 by having a second cooling channel 922 in the shape of an annulus that extends around the left side of the opening 410 and a third cooling channel 923 in the shape of an annulus that extends around the right side of the opening 410.

[0047] In any of the embodiments disclosed and described herein, at least a portion of the at least one cooling channel is offset from the opening by less than 15.0 mm, such as less than 10.0 mm, less than 8.0 mm, less than 6.0 mm, or less than 5.0 mm. Thus, in embodiments, at least a portion of the at least one cooling channel is offset from the opening by 0.5 mm to 15.0 mm, 5.0 mm to 15.0 mm, 10.0 mm to 15.0 mm, 0.5 mm to 10.0 mm, 5.0 mm to 10.0 mm, or 0.5 mm to 5.0 mm.

[0048] In any of the embodiments disclosed and described herein, the cooling 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.

[0049] It should be understood that the plasma window 140 may be cooled using any of the embodiments described herein. Indeed, operation of the beam accelerator system 100 may include generating a viscous plasma 310 in the plasma channel 141. The viscous 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 include deuterium, tritium, argon, or helium) to heat and ionize a portion of the target gas to form the viscous 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 Tesla coils, 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 viscous plasma 310 disposed in the plasma channel 141 of the plasma window 140 and into the target chamber 160. In the target chamber 160, the ion beam 111 reacts with the target gas to generate neutrons via a 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 viscous plasma 310 in the plasma channel 141. As described above with respect to Figures 4-9, the plate 142 may be cooled by directing a cooling fluid through one or more cooling channels to transfer heat from the opening 410 and the plate 142 to the cooling fluid, which cools the opening 410 and the plate 142.

[0050] As used herein, the terms "substantially," "about," and the like refer to the characteristic or measurement described thereafter within normal manufacturing tolerances and imperfections in the relevant art.

[0051] A first aspect includes a beam accelerator system operable to produce medical isotopes, the beam accelerator system comprising: an ion accelerator that generates a high energy 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 comprises a plurality of plates, each plate having an opening aligned with the openings of one or more adjacent plates to form a plasma channel, wherein one or more plates of the plurality of plates comprise an integral plate having an opening and one or more cooling channels, the one or more cooling channels extending into the integral plate at a first side and extending out of the integral plate at a second side of the integral plate, the one or more cooling channels extending within a thickness of the integral plate.

[0052] A second aspect includes the beam accelerator system of the first aspect, wherein the one or more cooling channels comprise a first cooling channel and a second cooling channel, the first cooling channel being generally parallel to the second cooling channel, the first cooling channel being positioned on a first side of the opening, and the second cooling channel being positioned on a second side of the opening.

[0053] A third aspect includes the beam accelerator system of the second aspect, wherein at least one of the first cooling channel and the second cooling channel has a smooth inner surface.

[0054] A fourth aspect includes the beam accelerator system of the second aspect, wherein at least one of the first cooling channel and the second cooling channel has a spiral design on an interior surface.

[0055] A fifth aspect includes the beam accelerator system of the second to fourth aspects, wherein the first cooling channel and the second cooling channel have a circular cross-sectional area.

[0056] A sixth aspect includes the beam accelerator system of any one of the first to fifth aspects, wherein the plurality of plates are formed from a thermally conductive metal selected from the group consisting of copper, silver, aluminum, and tungsten.

[0057] A seventh aspect includes the beam accelerator system of any one of the first to sixth aspects, wherein the inner wall of the opening is formed from a refractory metal.

[0058] An eighth aspect includes the beam accelerator system of any one of the first to seventh aspects, wherein the opening has a diameter of 1.0 mm to 10.0 mm.

[0059] A ninth aspect includes the beam accelerator system of the first to eighth aspects, wherein at least one point of the one or more cooling channels is offset from the opening by less than 15.0 mm.

[0060] A tenth aspect includes the beam accelerator system of the first to ninth aspects, wherein the diameter of the one or more cooling channels is between 0.5 mm and 5.0 mm.

[0061] An eleventh aspect includes a beam accelerator system operable to produce a medical isotope, the beam accelerator system comprising: an ion accelerator that generates a high energy 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, the plasma window comprising a plurality of plates, each plate comprising an opening aligned with an opening in one or more adjacent plates to form a plasma channel, one or more plates of the plurality of plates extending within a respective layer thickness of the one or more plates and interdigitating with one or more plates at a first side of the one or more plates to interdigitate with one or more adjacent plates. The upper plate includes a first cooling channel and a second cooling channel extending from the one or more plates at a second side of the upper plate, wherein the first cooling channel fits into the one or more plates at a first side of the one or more plates, extends adjacent to the second side of the opening, bends in a first direction to extend adjacent to the second side of the opening, bends in a second direction to extend from the one or more plates at the second side of the one or more plates, and the second cooling channel fits into the one or more plates at a first side of the one or more plates, extends to a third side of the opening, bends in the first direction to extend adjacent to the third side of the opening, bends in a second direction to extend adjacent to a fourth side of the opening, and extends from the second side of the one or more plates.

[0062] A twelfth aspect includes the beam accelerator system according to the eleventh aspect, wherein a longitudinal axis of the first cooling channel is positioned along a centerline that bisects a cross section of the opening.

[0063] A thirteenth aspect includes the beam accelerator system according to the eleventh and twelfth aspects, wherein the plurality of plates are formed from a thermally conductive metal selected from the group consisting of copper, silver, aluminum, and tungsten.

[0064] A fourteenth aspect includes the beam accelerator system according to any one of the eleventh to thirteenth aspects, wherein the inner wall of the opening is formed from a refractory metal.

[0065] A fifteenth aspect includes the beam accelerator system according to any one of the eleventh to fourteenth aspects, wherein the opening has a diameter of 1.0 mm to 10.0 mm.

[0066] A sixteenth aspect includes the beam accelerator system of any of the eleventh to fifteenth aspects, wherein at least one point of the one or more cooling channels is offset from the opening by less than 15.0 mm.

[0067] A seventeenth aspect includes the beam accelerator system of any of the eleventh to sixteenth aspects, wherein the diameter of the one or more cooling channels is between 0.5 mm and 5.0 mm.

[0068] An eighteenth aspect includes a beam accelerator system operable to produce a medical isotope, the beam accelerator system comprising: an ion accelerator that generates a high energy ion beam; a low pressure chamber; an anode adjacent to and fluidly connected with the low pressure chamber; a plasma window adjacent to and fluidly connected with the anode; and a cathode housing adjacent to and fluidly connected with the plasma window, the plasma window comprising a plurality of plates, each plate comprising an opening aligned with the openings of one or more adjacent plates to form a plasma channel, one or more plates of the plurality of plates comprising a first cooling channel, a second cooling channel, and a cathode housing extending within respective layer thicknesses of the one or more plates. and a third cooling channel, wherein the first cooling channel fits into the one or more plates at a first edge of the one or more plates, extends to a first side of the opening, and branches into a second cooling channel and a third cooling channel, the second cooling channel extends in a first direction adjacent to the first side of the opening to a second side of the opening, turns in a second direction, extends adjacent to the second side of the opening, and extends out of the one or more plates at the second edge of the one or more plates, and the third cooling channel extends in a third direction adjacent to the first side of the opening to a third side of the opening, turns in the second direction, extends adjacent to the third side of the opening, and extends out of the one or more plates at the second edge of the one or more plates.

[0069] A nineteenth aspect includes the beam accelerator system according to the eighteenth aspect, wherein the first direction and the third direction are substantially perpendicular to the first cooling channel.

[0070] A twentieth aspect includes the beam accelerator system according to the eighteenth or nineteenth aspects, wherein the second direction is substantially parallel to the first direction.

[0071] A twenty-first aspect includes the beam accelerator system according to any one of the eighteenth to twentieth aspects, wherein the plurality of plates are formed from a thermally conductive metal selected from the group consisting of copper, silver, aluminum, and tungsten.

[0072] A twenty-second aspect includes the beam accelerator system according to any one of the eighteenth to twenty-first aspects, wherein the inner wall of the opening is formed from a refractory metal.

[0073] A twenty-third aspect includes the beam accelerator system according to any one of the eighteenth to twenty-second aspects, wherein the opening has a diameter of 1.0 mm to 10.0 mm.

[0074] A twenty-fourth aspect includes the beam accelerator system of any of the eighteenth to twenty-third aspects, wherein at least one point of the one or more cooling channels is offset from the opening by less than 15.0 mm.

[0075] A twenty-fifth aspect includes the beam accelerator system of any of the eighteenth to twenty-fourth aspects, wherein the diameter of the one or more cooling channels is between 0.5 mm and 5.0 mm.

[0076] A twenty-sixth aspect includes a beam accelerator system operable to produce a medical isotope, the beam accelerator system comprising: an ion accelerator that generates a high energy ion beam; a low pressure chamber; an anode adjacent to and fluidly connected with the low pressure chamber; a plasma window adjacent to and fluidly connected with the anode; and a cathode housing adjacent to and fluidly connected with the plasma window, the plasma window comprising a plurality of plates, each plate comprising an opening aligned with the openings of one or more adjacent plates to form a plasma channel, one or more plates of the plurality of plates comprising a first portion of a first cooling channel, a second cooling channel, a third cooling channel, a a cooling channel and a second portion of the first cooling channel, wherein the first portion of the first cooling channel fits into the plate at a first edge of the plate, extends to a first side of the opening, and branches into a second cooling channel and a third cooling channel, the second cooling channel extends around the first portion of the opening, the third cooling channel extends around the second portion of the opening, the second cooling channel and the third cooling channel meet on the second side of the opening to form the second portion of the first cooling channel, and the second portion of the first cooling channel extends out of the plate at a second edge of the plate, and the second cooling channel and the third cooling channel form an annular cooling channel around the opening.

[0077] A twenty-seventh aspect includes the beam accelerator system according to the twenty-sixth aspect, wherein the plurality of plates are formed from a thermally conductive metal selected from the group consisting of copper, silver, aluminum, and tungsten.

[0078] A twenty-eighth aspect includes the beam accelerator system according to the twenty-sixth to twenty-seventh aspects, wherein the inner wall of the opening is formed from a refractory metal.

[0079] A twenty-ninth aspect includes the beam accelerator system according to any one of the twenty-sixth to twenty-eighth aspects, wherein the opening has a diameter of 1.0 mm to 10.0 mm.

[0080] A thirtieth aspect includes the beam accelerator system of the twenty-sixth to twenty-ninth aspects, wherein at least one point of the one or more cooling channels is offset from the opening by less than 15.0 mm.

[0081] A thirty-first aspect includes the beam accelerator system of any of the twenty-sixth to thirtieth aspects, wherein the diameter of the one or more cooling channels is between 0.5 mm and 5.0 mm. [Example]

[0082] The embodiments will be further clarified by the following examples.

[0083] The examples provided below were modeled using COMSOL software.

[0084] Example 1 A plate was modeled with the cooling channel design shown in Figure 4. The aperture diameter was set to 10 mm and the aperture power was 1 kW / cm 2 The cooling channel diameter was set to 3 mm, the cooling channel was offset from the opening by 9.525 mm, and the cooling fluid was set as water with an inlet temperature of 20°C.

[0085] The above simulation was performed. The cooling channels had a circular cross-sectional shape and a smooth interior. The simulation was performed again under the same conditions, except that the interior of the channel had a circular cross-sectional shape and a spiral design on the interior of the cooling channel. Figure 10A shows the results of the simulation when the cooling channel had a smooth interior, and Figure 10B shows the results of the simulation when the cooling channel had a spiral design on the interior.

[0086] The graph in Figure 10A provides temperature (°C) on the left y-axis versus cooling water flow rate (gallons / min) on the x-axis for maximum orifice temperature and maximum cooling channel temperature. The graph in Figure 10A provides cooling channel pressure drop (psi) on the right y-axis versus cooling water flow rate (gallons / min) on the x-axis. As shown in Figure 10A, the pressure drop begins to increase sharply at flow rates between 2.5 gallons / min and 3.0 gallons / min, while the orifice temperature and cooling channel temperature plateau near flow rates between 2.5 gallons / min and 3.0 gallons / min.

[0087] The graph in Figure 10B provides temperature (°C) on the left y-axis versus cooling water flow rate (gallons / min) on the x-axis for maximum orifice temperature and maximum cooling channel temperature. The graph in Figure 10B provides cooling channel pressure drop (psi) on the right y-axis versus cooling water flow rate (gallons / min) on the x-axis. As shown in Figure 10B, the pressure drop begins to increase sharply at flow rates between 2.5 gallons / min and 3.0 gallons / min, while the orifice temperature and cooling channel temperature plateau near flow rates between 2.5 gallons / min and 3.0 gallons / min.

[0088] 10A and 10B show that at low cooling fluid flow rates, the temperature of the openings and cooling channels is lower in the cooling channels with a spiral design interior (shown in FIG. 10B) than in the cooling channels with a smooth interior (shown in FIG. 10A). Meanwhile, the pressure drop increases much more steeply in the cooling channel design with a spiral design interior of the cooling channel (shown in FIG. 10B) compared to the cooling channel design with a smooth interior of the cooling channel (shown in FIG. 10A).

[0089] Example 2 A plate with an L-shaped channel design was modeled as shown in Figure 7. The aperture diameter was set to 10 mm and the aperture power was 1 kW / cm 2 The cooling channel diameter was set to 3 mm, the cooling channel was offset from the opening by 9.525 mm, and the cooling fluid was set as water with an inlet temperature of 20° C. The interior of the cooling channel had a circular cross-sectional shape and a smooth inner surface.

[0090] The graph in Figure 11 provides temperature (°C) on the left y-axis versus cooling water flow rate (gallons / min) on the x-axis for maximum orifice temperature and maximum cooling channel temperature. The graph in Figure 11 provides cooling channel pressure drop (psi) on the right y-axis versus cooling water flow rate (gallons / min) on the x-axis. As shown in Figure 11, the pressure drop begins to increase sharply at flow rates between 2.5 gallons / min and 3.0 gallons / min, while the orifice temperature and cooling channel temperature plateau near flow rates between 2.5 gallons / min and 3.0 gallons / min.

[0091] As shown by comparing Figures 10B and 11, the L-shaped channel design has a trade-off between peak cooling channel temperature and peak opening temperature. While the L-shaped channel design has a significantly higher pressure drop (approximately 95 psi) than the cooling channel design in Example 1 with smooth cooling channel interiors, the L-shaped cooling channel design does not have as much pressure drop (approximately 40 psi) as the cooling channel design in Example 1 with spiral-design cooling channel interiors. The L-shaped channel design also has a maximum dissipation of 10 kW per plate. Thus, the L-shaped channel design has a similar opening temperature to the design in Example 1 with spiral-design cooling channel interiors, but the L-shaped cooling channel design has a lower pressure drop.

[0092] Example 3 Simulations were performed for the following cooling channel designs: The cooling channel design of FIG. 4, except the cooling channels had a square cross-sectional shape and smooth inner surfaces. In the U-shaped cooling channel design shown in Figure 8A, the cooling channel had a circular cross-sectional shape and a smooth inner surface.

[0093] In each of the above designs, 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 channel was offset from the opening by 9.525 mm, and the cooling fluid was set as water with an inlet temperature of 20°C.

[0094] 12-14 graphically illustrate the results of the above simulations and the simulations of Examples 1 and 2. In Figures 12-14, the cooling channel design of Example 1 having a smooth interior is labeled "Circular," the cooling channel design with a square cross-sectional shape is labeled "Square," the cooling channel design of Example 1 having a spiral design interior is labeled "Circular (Spiral)," the U-shaped cooling channel design is labeled "U-Tube," and the L-shaped cooling channel design of Example 2 is labeled "L-Channel."

[0095] Figure 12 graphs the maximum opening temperature (°C) along the y-axis versus the flow rate (gallons / min) along the x-axis. Figure 13 graphs the maximum cooling channel temperature (°C) along the y-axis versus the flow rate (gallons / min) along the x-axis. Figure 14 graphs the inlet pressure (psi) along the y-axis versus the flow rate (gallons / min) along the x-axis.

[0096] Circular and square cross-section cooling channels with smooth interiors result in the highest temperatures at both the openings and the cooling channels, but have a smaller impact on pressure. Circular and U-shaped cooling channel designs with spiral design interiors promote the lowest temperatures at both the openings and the cooling channels, but at a greater "cost" of pressure drop for each. The L-shaped cooling channel design offers a middle ground where the pressure drop is not as great as the circular and U-shaped cooling channel designs with spiral design interiors, but the L-shaped cooling channel design results in lower peak temperatures at both the openings and the cooling channels than the circular and U-shaped cooling channel designs with spiral design interiors.

[0097] It should 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, this specification is intended to cover modifications and variations of the various embodiments described herein, provided that such modifications and variations come within the scope of the following 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; Equipped with the plasma window comprising a plurality of plates, each plate having an opening aligned with an opening in one or more adjacent plates to form a plasma channel; 10. A beam accelerator system, wherein one or more of the plurality of plates comprises an integral plate having an opening and one or more cooling channels, the one or more cooling channels extending into the integral plate at a first side thereof and extending out of the integral plate at a second side thereof, the one or more cooling channels extending within a thickness of the integral plate.

2. the one or more cooling channels comprise a first cooling channel and a second cooling channel; the first cooling channel is generally parallel to the second cooling channel; 2. The beam accelerator system of claim 1, wherein the first cooling channel is positioned on a first side of the opening and the second cooling channel is positioned on a second side of the opening.

3. The beam accelerator system of claim 2 , wherein at least one of the first cooling channel and the second cooling channel has a smooth inner surface.

4. The beam accelerator system of claim 2 , wherein at least one of the first cooling channel and the second cooling channel has a spiral design on an inner surface.

5. The beam accelerator system of claim 2 , wherein the first cooling channel and the second cooling channel have a circular cross-sectional area.

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

7. The beam accelerator system of claim 1 , wherein the inner wall of the opening is formed from a refractory metal.

8. The beam accelerator system of claim 1 , wherein the opening has a diameter between 1.0 mm and 10.0 mm.

9. 10. The beam accelerator system of claim 1, wherein at least one point of said one or more cooling channels is offset from said opening by less than 15.0 mm.

10. The beam accelerator system of claim 1 , wherein the one or more cooling channels have a diameter of at least 0.5 mm and at most 5.0 mm.

11. 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; Equipped with the plasma window comprising a plurality of plates, each plate having an opening aligned with an opening in one or more adjacent plates to form a plasma channel; one or more of the plurality of plates includes a first cooling channel and a second cooling channel extending through each layer thickness of the one or more plates, the first cooling channel and the second cooling channel fitting into the one or more plates at a first side of the one or more plates and extending out of the one or more plates at a second side of the one or more plates; the first cooling channel enters the one or more plates at the first edge of the one or more plates, extends adjacent a first side of the opening, turns in a first direction to extend adjacent a second side of the opening, turns in a second direction and extends to exit the one or more plates at a second edge of the one or more plates; the second cooling channel penetrates the one or more plates at a first side of the one or more plates, extends to a third side of the opening, turns in the first direction to extend adjacent to the third side of the opening, turns in the second direction to extend adjacent to a fourth side of the opening, and extends from the second side of the one or more plates.

12. The beam accelerator system of claim 11 , wherein a longitudinal axis of the first cooling channel is positioned along a centerline that bisects a cross section of the opening.

13. 12. The beam accelerator system of claim 11, wherein said plurality of plates are formed from a thermally conductive metal selected from the group consisting of copper, silver, aluminum, and tungsten.

14. The beam accelerator system of claim 11 , wherein the inner wall of the opening is formed from a refractory metal.

15. The beam accelerator system of claim 11, wherein the opening has a diameter of between 1.0 mm and 10.0 mm.

16. 12. The beam accelerator system of claim 11, wherein at least one point of the first cooling channel or the second cooling channel is offset from the opening by less than 15.0 mm.

17. 12. The beam accelerator system of claim 11, wherein a diameter of at least one of the first cooling channel and the second cooling channel is equal to or greater than 0.5 mm and equal to or less than 5.0 mm.

18. 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; Equipped with the plasma window comprising a plurality of plates, each plate having an opening aligned with an opening in one or more adjacent plates to form a plasma channel; one or more plates of the plurality of plates include a first cooling channel, a second cooling channel, and a third cooling channel extending within respective thicknesses of the one or more plates; the first cooling channel fits into the one or more plates at a first edge of the one or more plates, extends to a first side of the opening, and branches into the second cooling channel and the third cooling channel; the second cooling channel extends in a first direction adjacent the first side of the opening to a second side of the opening, turns in a second direction, extends adjacent the second side of the opening, and extends from the one or more plates at a second edge of the one or more plates; the third cooling channel extends in a third direction adjacent the first side of the opening to a third side of the opening, turns in the second direction, extends adjacent the third side of the opening, and extends from the one or more plates at the second side of the one or more plates.

19. 20. The beam accelerator system of claim 18, wherein the first direction and the third direction are substantially perpendicular to the first cooling channel.

20. 20. The beam accelerator system of claim 18, wherein the second direction is substantially parallel to the first direction.

Images