Patent Application
20250168962
The present disclosure generally relates to plasma window systems, particularly plasma window systems used in a beam accelerator system, such as, for example, a gaseous target neutron generation system.
Beam accelerator systems may be used to generate neutrons via fusion for a variety of purposes, such as medical-grade radioactive isotope production, nuclear waste transmutation, fusion energy generation, and for use as a fusion-prototypic neutron source (FPNS). Generally speaking, beam accelerator systems include an ion accelerator that generates a high-energy ion beam that is directed to a target chamber. For instance, in gaseous target neutron generation systems, a high-energy ion beam is directed to a gaseous target.
According to one embodiment, a beam accelerator system comprises a beamline comprising a low-pressure chamber and an ion accelerator configured to generate an ion beam; a target chamber; and a plasma window assembly interposed between and fluidly connecting the beamline and the target chamber. The plasma window assembly comprises an anode and a plurality of cooling plates, each cooling plate comprising an aperture having an aperture axis that is aligned with an aperture axis of an aperture in one or more adjacent cooling plates to form a plasma channel, wherein one or more cooling plates of the plurality of cooling plates is a cathode plate comprising at least one cathode.
According to another embodiment, a beam accelerator system comprises a plurality of beamlines each comprising a low-pressure chamber and an ion accelerator configured to generate an ion beam; a target chamber coupled to each of the plurality of beamlines such that the plurality of beamlines direct the ion beams into the target chamber; and a plurality of plasma window assemblies, each plasma window assembly interposed between and fluidly connecting a respective beamline of the plurality of beamlines and the target chamber. Each plasma window assembly comprises an anode and a plurality of cooling plates, each cooling plate comprising an aperture having an aperture axis that is aligned with an aperture axis of an aperture in one or more adjacent cooling plates to form a plasma channel, wherein one or more cooling plates of the plurality of cooling plates is a cathode plate comprising at least one cathode.
According to another embodiment, a method comprises generating a plasma in a plasma channel of a plasma window assembly interposed between and fluidly connecting a beamline and a target chamber, wherein the beamline comprises a low pressure chamber and an ion accelerator that generates an ion beam; and directing the ion beam through the plasma and into the target chamber. The plasma window assembly comprises an anode and a plurality of cooling plates, each cooling plate comprising an aperture having an aperture axis that is aligned with an aperture axis of an aperture in one or more adjacent cooling plates to form the plasma channel. One or more cooling plates of the plurality of cooling plates is a cathode plate comprising at least one cathode.
Additional features and advantages of the systems and methods disclosed herein will be set forth in the detailed description that follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description that follows, the claims, as well as the appended drawings.
It is to 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 the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.
Reference will now be made in detail to embodiments of beam accelerator systems that include plasma windows, embodiments of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts.
Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that specific orientations be required with any apparatus. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.
Directional terms as used herein—for example up, down, right, left, front, back, top, bottom—are made only with reference to the figures as drawn and the coordinate axis provided therewith and are not intended to imply absolute orientation.
References herein to the positions of elements (e.g., “top,” “bottom,” “above,” “below”) are merely used to describe the orientation of various elements in the figures. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.
As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.
As utilized herein, the terms “approximately,” “about,” “substantially,” and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. Indeed, such terms refer to the subsequently listed property or measurement within normal manufacturing tolerances and imperfections in the relevant field. It should be understood by those of skill in the art that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical values or idealized geometric forms provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the disclosure as recited in the appended claims.
The term “coupled” and variations thereof, as used herein, means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members coupled directly to each other, with the two members coupled to each other using a separate intervening member and any additional intermediate members coupled with one another, or with the two members coupled to each other using an intervening member that is integrally formed as a single unitary body with one of the two members. If “coupled” or variations thereof are modified by an additional term (e.g., directly coupled), the generic definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means the joining of two members without any separate intervening member), resulting in a narrower definition than the generic definition of “coupled” provided above. Such coupling may be mechanical, electrical, or fluidic.
As used herein, “sample volume” refers to the volume of space available to place samples to be irradiated. The sample volume may be a space located outside of the target chamber. In some embodiments, the sample volume is a single, continuous volume and in other embodiments, the sample volume is comprised of multiple, separate volumes that collectively add up to the total sample volume size.
With reference now to
The beam accelerator systems 100 may be operative to produce neutrons via fusion reaction. These neutrons may be used, for example, to perform neutron radiography, to generate medical isotopes, to perform transmutation of radioisotopes, such as waste radioisotopes generated during the operation of a nuclear fission power plant, and to generate fusion power.
In some embodiments, the beam accelerator system 100 operates by first extracting a beam of deuterium from the ion accelerator 110, which may comprise an electron cyclotron resonance (ECR) based ion source. The deuterium beam is accelerated via stepped electrostatic potentials such that a desired deuterium-tritium fusion cross-section is achieved when the deuterium beam enters the gaseous tritium target, located in the target chamber 160, generating neutrons via a fusion reaction. In some embodiments, the deuterium beam is focused through a gas-flow-restricting aperture that separates the beam acceleration region (e.g., the low-pressure chamber 120) from the target chamber 160.
One key to generating neutrons over a small enough area to be useful is the ability to generate and maintain a large pressure gradient from the beam acceleration region (e.g., the low-pressure chamber 120) to the gaseous target chamber 160, which may be filled with tritium, particularly when generating neutrons for neutron radiography, medical isotope production, radioisotope transmutation, and fusion power generation. The beam acceleration region (e.g., the low-pressure chamber 120) operates under high vacuum conditions. In contrast, the gas target chamber 160, where neutrons may be generated, may operate at pressures over multiple powers of ten higher, for example, over a million times higher, to stop the ion beam over a short distance, e.g., approximately one meter. Current beam accelerator systems accomplish this pressure differential through a series of differentially pumped stages in which each stage is separated by a gas-flow-restricting aperture that will allow the ion beam to pass but restricts gas flow from higher to lower-pressure regions. The exhaust from each pumping stage is returned to the adjacent, higher-pressure stage.
Traditionally, such differentially pumped stages require large and expensive pumping infrastructure to maintain the low pressure required for the ions to be accelerated from the ion accelerator 110 while maximizing the pressure in the target chamber 160. Larger ion beam sizes and higher current ion beams require more pumping due to the conductance of the ion beam through a channel and into the target chamber 160. Therefore, the beam size and thus total yield of a system is limited by the diameter of the channel leading to the target chamber 160. Moreover, if the aperture were widened to allow more beam to pass, the gas flow from the high-pressure region to the low-pressure region would necessarily increase. This increase in gas flow would then reduce the pressure differential across the adjacent stages. Alternatively, if the diameter of the aperture were reduced, an increased pressure differential would be seen, though this reduction of aperture diameter would also require a reduction in beam current to make it possible to focus said beam through the now smaller cross-sectional area of the aperture.
With reference to
The plasma window 140 operates as a vacuum barrier to separate the low-pressure beam acceleration region (i.e., the low-pressure chamber 120 of the beamline 102) and the target chamber 160. The plasma window 140 allows for a greater pressure reduction factor relative to traditional channels, which allows the plasma channel 141, through which the ion beam 111 travels to reach the target chamber 160, to be widened. The widening of the plasma channel 141 enables larger and higher current ion beams 111 to pass into the target chamber 160, thereby enabling increased neutron generation and flux. Moreover, the gains from pressure reduction also reduce the total pumping cost due to the decrease in conductance and pumping hardware required to maintain the pressure differential. This change alone enables a significant reduction in length of the target chamber 160 and thus, a significant increase in neutron flux.
With reference to
As mentioned above, one or more cooling plates of the plurality of cooling plates 142 is a cathode plate 150 containing at least one cathode 151. In embodiments, the cathode plate 150 is positioned near the center of the plurality of cooling plates 142. In other embodiments, the cathode plate 150 may be positioned closer to one end of the plurality of cooling plates 142, which may result in the cathodes thereof functioning similarly to those of a traditional configuration. The aperture 143 of the cathode plate 150, herein referred to as the cathode plate aperture 153, may be fluidly coupled to the target chamber 160 and thereby contain some of the target gas housed in the target chamber 160. The target chamber 160 and the cathode plate aperture 153 may be pressurized by a pumping system, a gas bottle, or the like. Each cathode of the at least one cathode 151 may extend from the cathode plate 150 into the cathode plate aperture 153 and may apply a voltage (e.g., a voltage in a range of from 150 V to 5000 V) in the cathode plate aperture 153 to initiate and/or maintain the heating and ionization of a portion of the target gas, thereby forming a plasma 105, which may be a viscous plasma. The plasma 105 may comprise a wall-stabilized DC vacuum arc plasma formed within the plasma channel 141. Without intending to be limited by theory, the vacuum arc originates from the cathodes 151, which may comprise materials with low work function known to those skilled in the art, e.g., pure tungsten, thoriated tungsten, lanthanated tungsten, ceriated tungsten, zirconiated tungsten, lanthanum hexaboride, etc. The integration of a small amount of alloying elements such as thorium into tungsten allows it to maintain the refractory material properties of tungsten while reducing the work function of the material to generate much stronger thermionic emission than pure tungsten, thereby increasing the lifetime and thermal efficiency of the cathodes 151. In other words, the material used for the cathodes 151 affects the lifetime and the maximum discharge current of the cathodes 151.
While the cathodes 151, in some embodiments, may apply a voltage to both initiate and maintain the formation of the plasma 105, other methods of initiating formation of the plasma 105 are contemplated, such as using one or more initiation coils, such as tesla coils, to apply the initial voltage. Such initiation coils, while not depicted, may be mounted on one or more of the cooling plates 142 of the plasma window assembly 140. Attaching the initiation coils to the cooling plate closest to the cathode cooling plate 150 will generate ions and electrons within the vacuum system, initiating the arc discharge from the cathodes 151 to the anode 130, thereby forming the plasma 105. However, in embodiments, the initiation coils are attached at other locations, e.g., at one or more cooling plates spaced apart from the cathode cooling plate by at least one cooling plate. Moreover, in embodiments comprising initiation coils, the cathodes 151 may still apply a voltage to maintain the plasma 105.
As mentioned above, each cooling plate 142 comprises an aperture 143 having an aperture axis A that is aligned with an aperture axis A of an aperture 143 in one or more adjacent cooling plates 142 to form the plasma channel 141. In embodiments, the aperture 143 of each cooling plate 142 is circular and at or near the geometrical center of the cooling plate 142. However, the position of the aperture 143 in each cooling plate need not be centered provided sufficient cooling is maintained. When the plurality of plates 142 are aligned and connected, the coaxial apertures 143 in the cooling plates 142 form the plasma channel 141 through which the high-energy ion beam 111 will travel from the beamline 102 to the target chamber 160. It should be appreciated that in embodiments the apertures 143 in the cooling plates 142 need not be perfectly circular and may be any shape that can accommodate the transmission of the high-energy ion beam 111. Moreover, while the cooling plates 142 are depicted herein as generally square shaped, any suitable shape for the cooling plates 142 may be used. For example, in embodiments, the cooling plates 142 may be circular shaped, a hexagonal shaped, or octagonal shaped.
The cooling plates 142 of the plasma window assembly 140 are, in embodiments, electrically floating and cooled with a fluid, such as water, which will be discussed in more detail below. The cooling plates 142 may implement any suitable cooling channel design, such as those described in U.S. patent application Ser. No. 17/951,975 entitled “Cooling Plate Assembly for Plasma Windows Positioned in a Beam Accelerator System” or U.S. patent application Ser. No. 18/116,036, entitled “Jet Impingement Cooling Assembly For Plasma Windows Positioned In A Beam Accelerator System,” each of which is incorporated herein by reference in its entirety.
In one or more embodiments, separators may be positioned between portions of adjacent plates 142. The separators may provide electrical insulation and maintain a vacuum seal between the plates while also being able to withstand high temperatures and particles of plasma discharge. In embodiments, the separators may comprise a central spacer 144, e.g., a boron nitride, aluminum nitride, or alumina spacer, most proximate to the plasma channel 141, an O-ring 146, e.g., a Viton O-ring, surrounding the central spacer 144, and an outer spacer 148, e.g., a PVC or PEEK spacer, surrounding the O-ring 146. In order to provide longer lifetimes in high neutron environments brazed or diffusion bonded metal-to-ceramic seals may also be used as alternatives to O-rings.
The beam accelerator systems 100 disclosed herein may be used in methods comprising generating the plasma 105 in the plasma channel 141 of the plasma window assembly 140 interposed between and fluidly connecting the beamline 102 and the target chamber 160, and directing the ion beam 111 from the ion accelerator through the plasma 105 and into the target chamber 160. Generating the plasma 105 in the plasma channel 141 may comprise applying an input voltage to a target gas in the plasma channel 141, thereby heating and ionizing a portion of the target gas to form the plasma 105. As previously discussed, the target chamber 160 may house a target gas and the ion beam 111 may interact with the target gas to produce neutrons via a fusion reaction. The methods disclosed herein may further comprise impinging a sample volume with neutrons generated via a fusion reaction.
Therefore, a need exists for beam accelerator systems with plasma windows having reduced form factors that may also address the above-mentioned issues. The beam accelerator systems of the present disclosure include plasma window systems having reduced form factors wherein the size of the plasma window may be reduced in terms of the plasma window length, width, and height. In particular, the plasma window systems of the present disclosure offer improved cathode designs that are compatible with limited space requirements in the target area of beam accelerator systems, such as, for example, neutron generator systems. The cathode designs of the present disclosure involve embedding cathodes directly in one or more cooling plates of the plasma window system, i.e., so as to form the cathode plate discussed herein. By positioning the cathode plate such that it is central among the plurality of cooling plates, additional space may be made available near the target chamber, which may reduce design constraints that might otherwise be present. Moreover, the plasma window systems of the present disclosure provide several additional benefits, including: the avoidance of brazed joints exposed to vacuum or arc heating, self-biasing electron suppression, modular capabilities in that the position and number of cathode plates may be adjusted, simplified system fabrication, and improved ease of maintenance. These and other benefits will be readily apparent from the description and embodiments described herein.
An embodiment of the cathode plate 150 of the present disclosure will now be described in more detail with reference to
In the embodiment shown in
The direction in which the cooling fluid flows through each of the first cooing channel 162 and the second cooling channel 164 may be the same or opposite. In embodiments, the first and second cooling channels 162 and 164 may have a circular cross section with diameters sized according to the amount of cooling fluid throughput that is desired. In embodiments, the first and second cooling channels 162 and 164 may have a cross-section that is elliptical, square, rectangular, pentagonal, hexagonal, or octagonal. Of course, the cross-sectional dimensions, such as the diameter, of the first and second cooling channels 162 and 164 is limited by the thickness t of the cathode plate 150. The first and second cooling channels 162 and 164 may be spaced from the cathode axis CA by a separation distance LC, the size of which may be dictated by the size of the cathode plate aperture 153. In embodiments, the first and second cooling channels 162 and 164 are placed as close as possible to the cathodes 151 and the cathode aperture wall 154 while maintaining a small buffer to maintain vacuum integrity in case of material erosion or melting. In embodiments, the separation distance LC is equal to at least 0.5 times the diameter of the cooling channels, at least 1.0 times the diameter of the cooling channels, at least 1.5 times the diameter of the cooling channels, or at least 2.0 times the diameter of the cooling channels.
In embodiments, the first and second cooling channels 162 and 164 may, upon approaching the cathode plate aperture 153, deviate around the cathode plate aperture 153 before becoming substantially parallel again with the cathode axis CA. For example, the first cooling channel 162 may, upon approaching the cathode plate aperture 153, turn in an upward direction relative to
In embodiments, the cathode plate aperture 153 has a diameter DCP that is from 1.0 mm to 50.0 mm, such as from 1.0 mm to 40.0 mm, from 1.0 mm to 30.0 mm, from 1.0 mm to 25.0 mm, from 1.0 mm to 20.0 mm, from 1.0 mm to 15.0 mm, from 2.0 mm to 15.0 mm, from 5.0 mm to 50.0 mm, from 10.0 mm to 50.0 mm, from 10.0 mm to 45.0 mm, from 15.0 mm to 45.0 mm, from 15.0 mm to 40.0 mm, from 20.0 mm to 40.0 mm, from 20.0 mm to 35.0 mm, or from 25.0 mm to 35.0 mm. However, it should be understood that the diameter DCP is related to the maximum pressure differential that can be achieved with a given set of vacuum pumps as well as the power of the arc discharge. Accordingly, diameters DCP falling outside of the above ranges may be implemented for some applications of the beam accelerator system 100. Moreover, the diameter DCP of the cathode plate aperture 153 may be the same or different than the diameter DA of the aperture 143 of the cooling plates 142, as shown in
Each cathode 151 may comprise a cathode tip 152 that, in embodiments, protrudes radially inwards from the cathode aperture wall 154 of the cathode plate aperture 153 of the cathode plate 150. In embodiments, the cathodes 151 may be oriented such that the cathode axes CA are perpendicular to the beam axis A. In other embodiments, the cathodes 151 may be oriented such that the cathode axes CA form an angle with the beam axis A that is less or greater than 90 degrees.
In embodiments, the cathode tip 152 may protrude radially inwards from the cathode aperture wall to a protruding distance LP from the cathode aperture wall 154 of at least 1.0 mm, at least 2.0 mm, at least 3.0 mm, at least 4.0 mm, at least 5.0 mm, at least 6.0 mm, at least 7.0 mm, or at least 8.0 mm. In embodiments, the protruding distance LP of the cathode tip 152 may be greater than 8.0 mm. In embodiments, the protruding distance LP may be less than or equal to 8.0 mm, less than or equal to 7.00 mm, less than or equal to 6.00 mm, less than or equal to 5.00 mm, less than or equal to 4.00 mm, less than or equal to 3.00 mm, less than or equal to 2.00 mm, or less than or equal to 1.00 mm. In embodiments, the protruding distance LP of the cathode tip 152 may be between 0.01 times DCP and 0.5 times DCP, between 0.01 times DCP and 0.45 times DCP, between 0.05 times DCP and 0.45 times DCP, between 0.05 times DCP and 0.40 times DCP, between 0.10 times DCP and 0.40 times DCP, between 0.10 times DCP and 0.35 times DCP, between 0.15 times DCP and 0.35 times DCP, between 0.15 times DCP and 0.30 times DCP, or between 0.20 times DCP and 0.30 times DCP. In embodiments, the protruding distance LP of the cathode tip 152 may be less than or equal to 0.25 times DCP. In embodiments, the cathode tip 152 does not protrude from the cathode aperture wall 154.
In embodiments, the cathode tips 152 of the first cathode 151a and the second cathode 151b are spaced from each other in the cathode plate aperture 153 by a cathode tip spacing LT of between 0.01 times DCP and 0.95 times DCP, between 0.05 times DCP and 0.95 times DCP, between 0.05 times DCP and 0.90 times DCP, between 0.10 times DCP and 0.90 times DCP, between 0.10 times DCP and 0.80 times DCP, between 0.10 times DCP and 0.70 times DCP, between 0.10 times DCP and 0.60 times DCP, between 0.10 times DCP and 0.50 times DCP, between 0.15 times DCP and 0.50 times DCP, between 0.15 times DCP and 0.45 times DCP, between 0.20 times DCP and 0.45 times DCP, between 0.20 times DCP and 0.40 times DCP, between 0.25 times DCP and 0.40 times DCP, between 0.25 times DCP and 0.35 times DCP, or between 0.30 times DCP and 0.35 times DCP. In embodiments, the cathode tip spacing LT is greater than or equal to 1.0 times DCP. In embodiments wherein the cathode tips 152 extend to the beam axis A, the cathode tip spacing LT is zero.
In the embodiment shown in
With reference now to
In embodiments, the cathode plate 150 comprises a plurality of cathodes 151 radially arranged about the aperture axis A of the cathode plate 150. The radially spacing between cathodes 151 about the aperture axis A of the cathode plate 150 may be uniform or non-uniform.
With reference to
The first cooling channel 262 may enter the cathode plate 150 proximate the first cathode 251a, extend toward the cathode plate aperture 153 in a first direction DIR-1 (i.e., in the +x direction) parallel to the first cathode axis CA-1, turn in a second direction DIR-2 (i.e., in the +y direction) parallel to the second cathode axis CA-2, and exit the cathode plate 150 proximate the second cathode 251b. The second cooling channel 264 may enter the cathode plate 150 proximate the second cathode 251b, extend toward the cathode plate aperture 153 in a third direction DIR-3 (i.e., in the −y direction) opposite the second direction DIR-2, turn in the first direction DIR-1, and exit the cathode plate 150 proximate the third cathode 251c. The third cooling channel 266 may enter the cathode plate 150 proximate the third cathode 251c, extend toward the cathode plate aperture 153 in a fourth direction DIR-4 (i.e., in the −x direction) opposite the first direction DIR-1, turn in the third direction DIR-3, and exit the cathode plate 150 proximate the fourth cathode 251d. The fourth cooling channel 268 may enter the cathode plate 150 proximate the fourth cathode 251d, extend toward the cathode plate aperture 153 in the second direction DIR-2, turn in the fourth direction DIR-4, and exit the cathode plate 150 proximate the first cathode 251a.
Cooling fluid may flow through the first cooling channel 262 by entering the first cooling channel 262 proximate the first cathode 251a and exiting the first cooling channel 262 proximate the second cathode 251b, or vice versa. Cooling fluid may flow through the second cooling channel 264 by entering the second cooling channel 264 proximate the second cathode 251b and exiting the second cooling channel 264 proximate the third cathode 251c, or vice versa. Cooling fluid may flow through the third cooling channel 266 by entering the third cooling channel 266 proximate the third cathode 251c and exiting the third cooling channel 266 proximate the fourth cathode 251d, or vice versa. Cooling fluid may flow through the fourth cooling channel 268 by entering the fourth cooling channel 268 proximate the fourth cathode 251d and exiting the fourth cooling channel 268 proximate the first cathode 251a, or vice versa. Moreover, as discussed above with respect to the embodiment shown in
It should be understood that the cooling channel arrangement schematically depicted in
With reference now to
With reference now to
Additionally, the cooling plates on the high-pressure side of the cathode plate, e.g., more proximate to the target chamber, may self-bias and have electron suppression functionality without the need of an additional power supply. As such, the cooling plates on the high-pressure side of the cathode plate may avoid the need for electron suppression meshes or girds adjacent to the target chamber 160. However, in embodiments, an external power supply can apply a voltage to one or more of cooling plates 142b between cathode plate 150 and target chamber 160 (voltage negative with respect to the cathode voltage) to prevent unwanted electrons being driven into electrically grounded target chamber 160. Moreover, an electron suppression ring may be coupled to the cooling plate 142 most proximate to the target chamber to further suppress electron movement towards the target chamber 160.
The first plurality of cooling plates 142a may be adjacent and fluidly connected to the low-pressure chamber 120 of the beamline 102. The second plurality of cooling plates 142b may be adjacent and fluidly connected to the target chamber 160. Moreover, in addition to the cathode plate 150, embodiments of the plasma window assembly 140 may further comprise a second cathode plate 170, a third cathode plate (not shown), a fourth cathode plate (not shown), or even more than four cathode plates. The second, third, and fourth cathode plates may have any of the characteristics discussed above for the cathode plate 150, individually or in combination. As shown for the plasma window assembly 140 shown in
In embodiments, the cathode plate 150 may comprise a first cathode 151a and a second cathode 151b, wherein the first cathode 151a is positioned radially opposite the second cathode 151b with respect to the aperture axis A of the cathode plate 150. The first cathode 151a and the second cathode 151b in
With reference now to
Without wishing to be bound by theory, it is believed that the smaller physical size of the plasma window assemblies of the present disclosure may be important for high neutron flux applications (especially those involving multiple beamlines) due to increases in the volume available to the irradiation cavity. Moreover, some of the benefits of the reduced form factor plasma window assemblies of the present disclosure become clear in view of the beam accelerator system 200 shown in
Additionally, the incorporation of the cathodes of the plasma window within the stack of cooling plates rather than adjacent to the target region may beneficially free up space adjacent to the target region. For instance, in neutron generation systems, the peak neutron production volume can be directly adjacent to the plasma channel of the plasma window. As such, the absence of a cathode arrangement in this region, as shown in
With reference now to
Referring now to
Referring now to
While the embodiments shown in
According to a first aspect of the present disclosure, a beam accelerator system comprises a beamline comprising a low-pressure chamber and an ion accelerator configured to generate an ion beam; a target chamber; and a plasma window assembly interposed between and fluidly connecting the beamline and the target chamber. The plasma window assembly comprises an anode and a plurality of cooling plates, each cooling plate comprising an aperture having an aperture axis that is aligned with an aperture axis of an aperture in one or more adjacent cooling plates to form a plasma channel, wherein one or more cooling plates of the plurality of cooling plates is a cathode plate comprising at least one cathode.
A second aspect includes the first aspect, wherein the at least one cathode comprises a plurality of cathodes radially arranged about the aperture axis of the cathode plate.
A third aspect includes the second aspect, wherein the at least one cathode comprises a first cathode and a second cathode, the first cathode positioned radially opposite the second cathode with respect to the aperture axis of the cathode plate.
A fourth aspect includes the third aspect, wherein the first cathode and the second cathode define a cathode axis, and wherein the cathode plate further comprises one or more cooling channels extending through the cathode plate in a direction substantially parallel to the cathode axis.
A fifth aspect includes the second aspect, wherein the at least one cathode comprises four cathodes that are radially separated from adjacent cathodes of the four cathodes by 90°.
A sixth aspect includes the fifth aspect, wherein the four cathodes comprise a first cathode, a second cathode, a third cathode, and a fourth cathode, wherein the first cathode and the third cathode are radially opposite and define a first cathode axis, and wherein the second cathode and the fourth cathode are radially opposite and define a second cathode axis substantially perpendicular to the first cathode axis. The cathode plate further comprises a first cooling channel, a second cooling channel, a third cooling channel, and a fourth cooling channel that run through a thickness of the cathode plate, wherein: the first cooling channel enters the cathode plate proximate the first cathode, extends toward the aperture in a first direction parallel to the first cathode axis, turns in a second direction parallel to the second cathode axis, and exits the cathode plate proximate the second cathode; the second cooling channel enters the cathode plate proximate the second cathode, extends toward the aperture in a third direction opposite the second direction, turns in the first direction, and exits the cathode plate proximate the third cathode; the third cooling channel enters the cathode plate proximate the third cathode, extends toward the aperture in a fourth direction opposite the first direction, turns in the third direction, and exits the cathode plate proximate the fourth cathode; and the fourth cooling channel enters the cathode plate proximate the fourth cathode, extends toward the aperture in the second direction, turns in the fourth direction, and exits the cathode plate proximate the first cathode.
A seventh aspect includes any one of the first through sixth aspects, wherein each cathode of the at least one cathode comprises a cathode tip that protrudes radially inwards from an inner wall of the aperture of the cathode plate.
An eighth aspect includes the seventh aspect, wherein the cathode tip protrudes radially inwards to a distance from the inner wall that is less than or equal to 0.25 times DCP, where DCP is a diameter of the aperture.
A ninth aspect includes any one of the first through eighth aspects, wherein each cathode of the at least one cathode is electrically isolated from a remainder of the cathode plate.
A tenth aspect includes any one of the first through eighth aspects, wherein each cathode of the at least one cathode is not electrically isolated from a remainder of the cathode plate.
An eleventh aspect includes any one of the first through tenth aspects, wherein an inner wall of the aperture of the cathode plate is formed from a refractory metal.
A twelfth aspect includes any one of the first through eleventh aspects, wherein the plurality of cooling plates comprises a first plurality of cooling plates and a second plurality of cooling plates, and wherein the cathode plate is interposed between the first plurality of cooling plates and the second plurality of cooling plates.
A thirteenth aspect includes any one of the first through twelfth aspects, wherein the plurality of cooling plates comprises a second cathode plate comprising at least one cathode.
A fourteenth aspect includes the thirteenth aspect, wherein the second cathode plate is adjacent to the cathode plate, and wherein: the at least one cathode of the cathode plate comprises a first cathode and a second cathode, wherein the first cathode is positioned radially opposite the second cathode with respect to the aperture axis of the cathode plate, and wherein the first cathode and the second cathode define a first cathode axis; the at least one cathode of the second cathode plate comprises a third cathode and a fourth cathode, wherein the third cathode is positioned radially opposite the fourth cathode with respect to the aperture axis of the second cathode plate, and wherein the third cathode and the fourth cathode define a second cathode axis, and wherein the second cathode axis is perpendicular to the first cathode axis.
According to a fifteenth aspect of the present disclosure, a beam accelerator system comprises a plurality of beamlines each comprising a low-pressure chamber and an ion accelerator configured to generate an ion beam; a target chamber coupled to each of the plurality of beamlines such that the plurality of beamlines direct the ion beams into the target chamber; and a plurality of plasma window assemblies, each plasma window assembly interposed between and fluidly connecting a respective beamline of the plurality of beamlines and the target chamber. Each plasma window assembly comprises an anode and a plurality of cooling plates, each cooling plate comprising an aperture having an aperture axis that is aligned with an aperture axis of an aperture in one or more adjacent cooling plates to form a plasma channel, wherein one or more cooling plates of the plurality of cooling plates is a cathode plate comprising at least one cathode.
A sixteenth aspect includes the fifteenth aspect, wherein the at least one cathode comprises a plurality of cathodes radially arranged about the aperture axis of the cathode plate.
According to a seventeenth aspect of the present disclosure, a method comprises generating a plasma in a plasma channel of a plasma window assembly interposed between and fluidly connecting a beamline and a target chamber, wherein the beamline comprises a low pressure chamber and an ion accelerator that generates an ion beam; and directing the ion beam through the plasma and into the target chamber. The plasma window assembly comprises an anode and a plurality of cooling plates, each cooling plate comprising an aperture having an aperture axis that is aligned with an aperture axis of an aperture in one or more adjacent cooling plates to form the plasma channel. One or more cooling plates of the plurality of cooling plates is a cathode plate comprising at least one cathode
An eighteenth aspect includes the seventeenth aspect, wherein generating the plasma in the plasma channel comprises applying an input voltage to a target gas in the plasma channel, thereby heating and ionizing a portion of the target gas to form the plasma.
A nineteenth aspect includes any one of the seventeenth or eighteenth aspects, wherein the target chamber houses a target gas and the ion beam interacts with the target gas to produce neutrons via a fusion reaction.
A twentieth aspect includes any one of the seventeenth through nineteenth aspects, further comprising impinging a sample volume with neutrons generated via the fusion reaction.
While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications might be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. Thus, it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.
Although the figures and description may illustrate a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above. Such variation may depend, for example, on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations of the described methods could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps, and decision steps.
This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63/601,006, entitled “Reduced Form Factor Plasma Windows Positioned in a Beam Accelerator System,” filed Nov. 20, 2023, the details of which are incorporated by reference.
The present disclosure was developed with Government support under Contract No. DE-AR0001377 awarded by the United States Department of Energy. The Government has certain rights in the present disclosure.
| Number | Date | Country | |
|---|---|---|---|
| 63601006 | Nov 2023 | US |
