Ion-beam target assembly for generating neutron

Abstract

To provide a system, a device, a product, and a method for generating newtons with a high-energy ion-beam target (HEIB target) and a target backing configured to come into contact with a bottom face of the HEIB target to form, for example an ion-beam target assembly.SOLUTION: In a specific embodiment, a high energy ion beam (HEIB) target has a thickness smaller than a penetration depth of protons or deuterons in a high-energy ion beam to strike the target. In a specific embodiment, the target backing contains a hydrogen high-diffusion metal (e.g., palladium), has open spaces which are diffused throughout the target backing for reducing a proton diffusion length, and has a shape and a thickness such that all or substantially all protons or deuterons passing through the HEIB target are blocked. The present invention further provides a system, a device, and a method for changing the target in an ion-beam acceleration system.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 681,432, filed June 6, 2018, which is incorporated herein by reference in its entirety.

[0002] (Field) Provided herein are systems, devices, products, and methods for generating neutrons using a high-energy ion beam target (HEIB target) and a target backing configured to contact the bottom surface of the HEIB target (e.g., to create an ion beam target assembly). In certain embodiments, the HEIB target has a thickness less than the penetration depth of protons in the high-energy ion beam striking the target. In certain embodiments, the target backing comprises a high-hydrogen diffusion metal (e.g., palladium), has open spaces distributed throughout for reduced proton or deuteron diffusion distances, and has a shape and thickness such that all or virtually all protons or deuterons passing through the HEIB target are stopped. Also provided herein are systems, devices, and methods for modifying targets in ion beam accelerator systems. [Background technology]

[0003] (background) A known method for producing neutrons is to bombard a beryllium (Be) target with high-energy (>2 MeV) protons. The beryllium needs to be cooled to prevent melting and / or thermal deformation. Typical configurations are a Be disk brazed to a water-cooled block, or a Be block sealed in a holder and cooled directly on the backside (away from the beam) by water or other fluid. A consistent problem with this method is that the embedded protons embrittle and expand the material in which they are embedded. Ultimately, this results in direct physical degradation (spalling) of the target. A typical embedded dose limit before visible target damage occurs is about 10 18 protons / cm2 In high power density systems, visible damage can occur within minutes of exposure.

[0004] One approach to alleviating this problem is to make the Be target thinner than the stopping distance of the protons, so that relatively few protons are deposited in the Be. The depth to which the protons penetrate the material depends on the proton energy and the material being deposited. In the case of a direct fluid-cooled Be target, the protons are deposited into the cooling fluid, and no expansion occurs. However, the Be target is a vacuum barrier and is susceptible to damage from the proton beam. Target lifetime can be stochastic, and destruction would result in catastrophic flooding of the vacuum system, requiring a conservative replacement schedule. In the case of a Be target mounted on a fluid-cooled substrate, the protons are deposited into the substrate, which is susceptible to the same blister and sparring damage. However, target lifetime can be increased by selecting a substrate material that can absorb relatively large amounts of hydrogen. For example, tantalum can retain approximately 100 to 1,000 times the amount of hydrogen as Be before damage. In high-power systems, this can result in target lifetimes measured in excess of 100 hours, but still be finite. In such cases, the creation of a high neutron plume activates the material. What is needed is a design that can be optimized to reduce the production of long-lived radioisotopes. This would allow for easier and safer operation and maintenance of the target, as well as higher uptime for devices in which the target is utilized. Summary of the Invention [Means for solving the problem]

[0005] (overview) Provided herein are systems, devices, products, and methods for generating neutrons using a high-energy ion beam target (HEIB target) and a target backing configured to contact the bottom surface of the HEIB target (e.g., to create an ion beam target assembly). In certain embodiments, the HEIB target has a thickness less than the penetration depth of protons in the high-energy ion beam that strike the target. In some embodiments, the HEIB target comprises a metal selected from beryllium, uranium, lithium, lithium compounds, tungsten, and tantalum. In certain embodiments, the high-energy ion beam comprises protons and / or deuterons. In certain embodiments, the target backing comprises a high-hydrogen diffusion metal (e.g., palladium), has open spaces distributed throughout for reduced proton or deuteron diffusion distances, and has a shape and thickness such that all or virtually all protons or deuterons passing through the HEIB target are stopped. In some embodiments, the high-energy ion beam comprises hydrogen ions or deuterium ions. Provided herein are systems, devices, and methods for modifying targets within an ion beam accelerator system.

[0006] In some embodiments, provided herein is a system comprising: a) a high-energy ion beam target (HEIB target) having a top surface and a bottom surface, the HEIB target producing neutrons when exposed to a high-energy ion beam, the HEIB target having a thickness between the top surface and the bottom surface that is less than the penetration depth of protons in the high-energy ion beam; and b) a target backing comprising a high-hydrogen-diffusive metal (HHDM), the target backing having open spaces distributed throughout such that the proton diffusion distance or deuteron diffusion distance is reduced throughout the target backing compared to if the target backing were a solid piece without the open spaces, the target backing configured to be positioned in contact with the bottom surface of the HEIB target, the target backing having a shape and thickness such that when positioned in contact with the HEIB target, all or substantially all of the protons or deuterons in the high-energy ion beam passing through the HEIB target are stopped by the target backing. In certain embodiments, the ion beam comprises protons. In other embodiments, the ion beam comprises deuterons. In some embodiments, the HEIB target comprises a metal selected from beryllium, uranium, lithium, lithium compounds, tungsten, and tantalum.

[0007] In certain embodiments, provided herein is a product comprising: a) an ion beam target assembly, the ion beam assembly comprising: i) a high-energy ion beam target (HEIB target) having a top surface and a bottom surface, the HEIB target producing neutrons when exposed to a high-energy ion beam, the HEIB target having a thickness between the top surface and the bottom surface that is less than the penetration depth of protons in the high-energy ion beam; and ii) a target backing comprising a high-hydrogen-diffusive metal (HHDM), the target backing having open spaces distributed throughout such that the proton or deuteron diffusion distance is reduced throughout the target backing compared to if the target backing were a solid piece without the open spaces, the target backing attached to the bottom surface of the HEIB target, the target backing having a shape and thickness such that all or substantially all of the protons or deuterons in the high-energy ion beam passing through the HEIB target are stopped by the target backing. In some embodiments, the HEIB target comprises a metal selected from beryllium, uranium, lithium, lithium compounds, tungsten, and tantalum.

[0008] In certain embodiments, provided herein are methods for generating neutrons, the method comprising: a) inserting both a HEIB target and a target backing (which are in contact with each other), or an ion beam target assembly, into a target chamber of an ion beam accelerator system as described herein; and b) generating a high-energy ion beam using the ion accelerator system, such that the high-energy ion beam strikes the HEIB target, thereby generating neutrons. In certain embodiments, the method further comprises c) collecting at least some of the neutrons. In other embodiments, step b) is performed continuously for at least 2 days (e.g., 2...5...20...45...100...1000 days) without destruction of the HEIB target. In further embodiments, step b) is performed continuously for at least 14 days without destruction of the HEIB target.

[0009] In some embodiments, the open spaces in the target backing are selected from pores, grooves, holes, corrugations, channels, open cells, honeycomb cells, dimples, irregular openings, or any combination thereof. In certain embodiments, the target backing is attached or configured to be attached to the bottom surface of the HEIB target by brazing, welding, diffusion bonding, or any other method that results in low temperature resistance.

[0010] In certain embodiments, the systems and articles of manufacture further comprise a cooled substrate. In some embodiments, the target backing is attached or configured to be attached to the cooled substrate. In further embodiments, the cooled substrate comprises a water-cooled substrate or a glycol-cooled substrate. In other embodiments, the cooled substrate comprises copper and / or aluminum.

[0011] In some embodiments, the HEIB target comprises i) a first layer comprising a metal (e.g., beryllium, uranium, lithium, tungsten, and tantalum) and ii) a second layer comprising a metal different from that used in the first layer, selected from the group consisting of beryllium, uranium, lithium, tungsten, and tantalum. In certain embodiments, the HEIB target comprises a first layer composed of beryllium and a second layer composed of uranium. In certain embodiments, the use of multiple layers within the target is employed to decelerate the ion beam as it traverses the target, which slows the ion beam from its original energy to a lower energy (mostly due to electron interactions). In some embodiments, using different materials at different lengths (energies) along the beam path allows for better optimization of neutron yield, energy, and angular distribution.

[0012] In some embodiments, the HEIB target has a thickness between 1 mm and 15 mm (e.g., 1 mm...3 mm...10 mm...12 mm...and 15 mm) and a diameter between 20 mm and 100 mm (e.g., 20 mm...45 mm...65 mm...and 100 mm). In certain embodiments, the thickness of the target backing is between 2 mm and 10 mm (e.g., 2 mm...5 mm...7.5 mm...and 10 mm). In some embodiments, the HEIB target and target backing are generally disk-shaped, square, octagonal, oval, or rectangular, and have the same diameter. HEIB targets are designed so that the high-energy ion beam strikes the target at a 90-degree or non-90-degree angle of incidence (e.g., 45 degrees...60 degrees...30 degrees, etc.), which has the effect of increasing the range over which the beam strikes the target and therefore reducing the power density of the beam by a geometrical quantity. In some embodiments, such targets have an oval, rectangular, or other elongated shape in the direction of the target tilt.

[0013] In certain embodiments, at least 94% (e.g., 95%, 98%, 99%, or 100%) of the HEIB target is a metal selected from beryllium, uranium, lithium, lithium compounds, tungsten, and tantalum. In further embodiments, the high hydrogen diffusion metal (HHDM) comprises palladium. In other embodiments, the high hydrogen diffusion metal (HHDM) is selected from the group consisting of palladium, titanium, vanadium, niobium, zirconium, and any combination thereof (e.g., a combination of vanadium and palladium). In certain embodiments, the HHDM is comprised of a combination of these elements, particularly a less expensive material (e.g., vanadium) coated with a thin layer of a more expensive material (e.g., palladium) known to have excellent hydrogen surface diffusion properties. In some embodiments, at least 94% (e.g., 95%, 97.5%, 99%, or 100%) of the target backing is a high hydrogen diffusion metal (HHDM). In a particular embodiment, the target backing consists of a solid vanadium core coated with a thin film of palladium.

[0014] In additional embodiments, the systems and articles of manufacture further comprise a target chamber. In certain embodiments, a target backing is positioned (e.g., attached) to the bottom surface of the HEIB target, thereby creating an ion beam target assembly, and the ion beam target assembly is located within the target chamber. In other embodiments, the systems and articles of manufacture further comprise an ion source configured to produce an ion beam (e.g., a proton beam or a deuteron beam), and an accelerator operably coupled to the ion source and configured to receive the ion beam and accelerate the ion beam to create a high-energy ion beam. In further embodiments, the target backing is attached to the bottom surface of the HEIB target, thereby creating an ion beam target assembly, and the system further comprises a target chamber containing the ion beam target assembly. In further embodiments, the ion beam target assembly is sized and positioned inside the target chamber such that destruction of the HEIB target does not result in a vacuum breach in the accelerator.

[0015] In some embodiments, the protons or deuterons in the high-energy ion beam are greater than 2 MeV. In further embodiments, when a backing component is positioned in contact with the bottom surface of the HEIB target, the HEIB target can be exposed to the high-energy ion beam for a total of at least 24 hours (e.g., 24...50...100...or 1000 hours) longer before destruction than when the HEIB target is not positioned in contact with the backing component. In further embodiments, when a backing component is positioned in contact with the bottom surface of the HEIB target, the HEIB target can be exposed to the high-energy ion beam for a total of at least 7 days (e.g., 7...25...100...or 1000 days longer) before destruction than when the HEIB target is not positioned in contact with the backing component.

[0016] In an additional embodiment, provided herein is a system comprising: a) an ion source configured to produce an ion beam; b) an accelerator operably coupled to the ion source and configured to receive the ion beam and accelerate the ion beam to produce an accelerated ion beam; and c) a target chamber comprising a target holding mechanism configured to: i) hold a target that generates neutrons when struck by the accelerated ion beam and becomes a radioactive target over time; and ii) allow the radioactive target to be removed from the target chamber with at least one long-handled tool, wherein the long-handled tool prevents a user of the long-handled tool from being irradiated.

[0017] In certain embodiments, provided herein are methods comprising: a) inserting a first target of a set of at least two targets into an ion beam accelerator; b) operating the ion beam accelerator for a length of time such that an ion beam strikes the first target, thereby generating neutrons and causing the first target to become a first radioactive target; c) removing the first radioactive target from the ion beam accelerator; d) inserting a second target of the set of at least two targets into the ion beam accelerator; and e) operating the ion beam accelerator for a length of time such that an ion beam strikes the first target, thereby generating neutrons and causing the first target to become a first radioactive target. f) identifying that the first radioactive target has cooled over time to become substantially or completely non-radioactive to produce a cooled first target, and inserting the cooled first target into an ion beam accelerator; and g) operating the ion beam accelerator for a length of time to cause the ion beam to strike the cooled first target, thereby generating neutrons and making the first cooled target again a radioactive first target.

[0018] In certain embodiments, the at least two targets are at least five targets, including a first target and a second target, and a third target, a fourth target, and a fifth target, and steps a) and b) are repeated with the third target, then the fourth target, then the fifth target. In other embodiments, steps f) and g) are repeated with the second target, the third target, the fourth target, and the fifth target after each has cooled. In additional embodiments, the at least two targets are at least 10 targets.

[0019] In some embodiments, provided herein is a system comprising: (a) an ion source configured to produce an ion beam; (b) an accelerator operatively coupled to the ion source and configured to receive the ion beam and accelerate the ion beam to produce an accelerated ion beam; (c) a target chamber configured to receive the accelerated ion beam; and (d) a target alteration mechanism configured to: (i) hold a plurality of targets, each target producing neutrons when struck by the accelerated ion beam within the target chamber; (ii) hold one of the plurality of targets at a first position within the target chamber and in a path of the accelerated ion beam, and hold the remaining targets outside the target chamber; and (iii) move the target at the first position to a position outside the target chamber and move one of the remaining targets to a first position within the target chamber. In further embodiments, when not at the first position, at least one of the plurality of targets is at a position outside the chamber that allows any accumulated radiation to substantially or completely dissipate. In other embodiments, at least one of the plurality of targets can be removed from the system when not at the first position without stopping or disrupting operation of the accelerated ion beam. In certain embodiments, the target changing mechanism comprises a carousel, turret, or magazine (which allows targets to be moved without human intervention or without human intervention other than actuating the target changing mechanism). In certain embodiments, at least one of the plurality of targets is automatically deposited into the radiation container when not at the first position. In additional embodiments, the target changing mechanism is further configured to allow one or more additional targets to be added and held by the target changing mechanism without stopping or disrupting operation of the accelerated ion beam.

[0020] In certain embodiments, provided herein is a device including a target changing mechanism in an ion beam accelerator having a target chamber, the target changing mechanism being configured to: a) hold a plurality of targets, each of which produces neutrons when struck by an accelerated ion beam in the target chamber; b) hold one of the plurality of targets at a first position inside the target chamber and in a path of the accelerated ion beam, and hold the remaining targets outside the target chamber; and c) move the target at the first position to a position outside the target chamber and move one of the remaining targets to a first position inside the target chamber.

[0021] In certain embodiments, the target, target retention mechanism, target chamber, brazing and / or welding materials, fixtures, and all other components are selected to minimize the production of long-lived (e.g., 120-day half-lives) radioisotopes resulting from neutron capture and other neutron reactions. Utilizing these materials allows for easier and safer target operation and maintenance, as well as higher uptime for devices in which these materials are utilized. Furthermore, reduced target activity allows for easier certification and disposal. Exemplary materials include aluminum, vanadium, aluminum bronze, and aluminum-based brazes (e.g., 1100 and 4043). The present invention provides, for example, the following items. (Item 1) 1. A system comprising: a) a high energy ion beam target (HEIB target) comprising a metal and having a top surface and a bottom surface; the metal is selected from the group consisting of beryllium, uranium, lithium, tungsten, and tantalum; the high-energy ion beam comprises protons and / or deuterons; the HEIB target produces neutrons when exposed to a high-energy ion beam; the HEIB target having a thickness between the top and bottom surfaces that is less than a penetration depth of protons or deuterons in the high-energy ion beam; b) a target backing comprising a high hydrogen diffusivity metal (HHDM), the target backing has open spaces distributed throughout, whereby proton or deuteron diffusion distances are reduced throughout the target backing compared to if the target backing were a solid piece without the open spaces; the target backing is configured to be positioned in contact with the bottom surface of the HEIB target; the target backing has a shape and thickness such that when the target backing is positioned in contact with the HEIB target, all or substantially all of the protons and / or deuterons in the high-energy ion beam passing through the HEIB target are stopped by the target backing. A system comprising: (Item 2) The system of claim 1, wherein the open spaces are selected from pores, grooves, holes, corrugations, channels, open cells, honeycomb cells, irregular openings, or any combination thereof. Item 10. The system of item 1, wherein the target backing is attached or configured to be attached to the bottom surface of the HEIB target by brazing, welding, soldering, diffusion, or bonding. (Item 4) c) The system of item 1, further comprising a cooled substrate. (Item 5) Item 5. The system of item 4, wherein the target backing is attached to or configured to be attached to the cooled substrate. (Item 6) Item 1. The system of item 1, wherein the HEIB target comprises: i) a first layer comprising the metal; and ii) a second layer comprising a metal different from that used in the first layer, the metal being selected from the group consisting of beryllium, uranium, lithium, tungsten, and tantalum. (Item 7) Item 5. The system of item 4, wherein the cooled substrate comprises copper and / or aluminum. (Item 8) Item 1. The system of item 1, wherein the HEIB target has a thickness between 2 mm and 25 mm and a diameter between 25 mm and 150 mm. (Item 9) Item 10. The system of item 1, wherein the thickness of the target backing is between 2 mm and 10 mm. (Item 10) Item 10. The system of item 1, wherein the target backing comprises a core of solid vanadium coated with a thin film of palladium. (Item 11) Item 12. The system of item 1, wherein at least 94% of the HEIB targets are the metal. Item 13. The system of item 1, wherein the high hydrogen diffusivity metal (HHDM) comprises palladium. Item 10. The system of item 1, wherein the high hydrogen diffusivity metal (HHDM) is selected from the group consisting of palladium, titanium, vanadium, niobium, zirconium, and any combination thereof. (Item 14) Item 10. The system of item 1, wherein at least 94% of the target backing is the high hydrogen diffusivity metal (HHDM). (Item 15) c) The system of item 1, further comprising a target chamber. (Item 16) Item 16. The system of item 15, wherein the target backing is positioned on or attached to the bottom surface of the HEIB target, thereby creating an ion beam target assembly, and the ion beam target assembly is located within the target chamber. (Item 17) Item 1, further comprising: c) an ion source configured to produce an ion beam; and d) an accelerator operably coupled to the ion source and configured to receive the ion beam and accelerate the ion beam to produce the high-energy ion beam. (Item 18) Item 18. The system of item 17, wherein the target backing is attached to the bottom surface of the HEIB target, thereby creating an ion beam target assembly, and the system further comprises: e) a target chamber containing the ion beam target assembly. (Item 19) 20. The system of claim 18, wherein the ion beam target assembly is sized and positioned inside the target chamber such that destruction of the HEIB target does not result in a vacuum breach in the accelerator. (Item 20) Item 2. The system of item 1, wherein the protons or deuterons in the high-energy ion beam are protons or deuterons greater than 2 MeV. (Item 21) 2. The system of claim 1, wherein the HEIB target can be exposed to the high-energy ion beam for at least a total of 24 hours longer before destruction when the backing component is positioned in contact with the bottom surface of the HEIB target compared to when the HEIB target is not positioned in contact with the backing component. (Item 22) 2. The system of claim 1, wherein the HEIB target can be exposed to the high-energy ion beam for at least a total of 7 days longer before destruction when the backing component is positioned in contact with the bottom surface of the HEIB target compared to when the HEIB target is not positioned in contact with the backing component. (Item 23) 1. An article of manufacture comprising: a) an ion beam target assembly, the ion target beam assembly comprising: i) a high energy ion beam target (HEIB target) comprising a metal and having a top surface and a bottom surface; the metal is selected from the group consisting of beryllium, uranium, lithium, tungsten, and tantalum; the high-energy ion beam comprises protons and / or deuterons; the HEIB target produces neutrons when exposed to a high-energy ion beam; a high-energy ion beam target, the HEIB target having a thickness between the top surface and the bottom surface, the thickness between the top surface and the bottom surface being less than a penetration depth of protons or deuterons in the high-energy ion beam; ii) a target backing comprising a high hydrogen diffusivity metal (HHDM), the target backing has open spaces distributed throughout, thereby reducing the proton or deuteron diffusion distance throughout the target backing compared to if the target backing were a solid piece without the open spaces; the target backing is attached to the bottom surface of the HEIB target; the target backing has a shape and thickness such that all or substantially all of the protons or deuterons in the high energy ion beam passing through the HEIB target are stopped by the target backing; A product comprising: (Item 24) 24. The system of claim 23, wherein the open spaces are selected from pores, grooves, holes, corrugations, channels, open cells, honeycomb cells, irregular openings, or any combination thereof. (Item 25) 24. The system of claim 23, wherein the target backing is attached to the bottom surface of the HEIB target by brazing, soldering, welding, or diffusion bonding. (Item 26) b) The system of item 23, further comprising a cooled substrate. (Item 27) Item 24. The system of item 23, wherein the HEIB target comprises: i) a first layer comprising the metal; and ii) a second layer comprising a metal different from that used in the first layer, the metal being selected from the group consisting of beryllium, uranium, lithium, tungsten, and tantalum. (Item 28) 27. The system of claim 26, wherein the cooled substrate comprises copper and / or aluminum. (Item 29) 24. The system of claim 23, wherein the HEIB target has a thickness between 2 mm and 25 mm and a diameter between 25 mm and 150 mm. (Item 30) 24. The system of claim 23, wherein the thickness of the target backing is between 2 mm and 10 mm. (Item 31) 24. The system of claim 23, wherein the target backing comprises a core of solid vanadium coated with a thin film of palladium. (Item 32) 24. The system of claim 23, wherein at least 95% of the HEIB targets are the metal. (Item 33) 24. The system of claim 23, wherein the high hydrogen diffusivity metal (HHDM) comprises palladium. (Item 34) 24. The system of claim 23, wherein the high hydrogen diffusivity metal (HHDM) is selected from the group consisting of palladium, titanium, vanadium, niobium, zirconium, and any combination thereof. (Item 35) 24. The system of claim 23, wherein at least 95% of the target backing is the high hydrogen diffusivity metal (HHDM). (Item 36) b) The system of item 23, further comprising a target chamber. (Item 37) Item 37. The system of item 36, wherein the ion beam target assembly is located within the target chamber. (Item 38) 24. The system of claim 23, further comprising: b) an ion source configured to produce an ion beam; and c) an accelerator operably coupled to the ion source and configured to receive the ion beam and accelerate the ion beam to produce the high-energy ion beam. (Item 39) e) The system of claim 38, further comprising a target chamber containing the ion beam target assembly. (Item 40) 40. The system of claim 39, wherein the ion beam target assembly is sized and positioned inside the target chamber such that destruction of the HEIB target does not result in a vacuum breach in the accelerator. (Item 41) 24. The system of claim 23, wherein the protons or deuterons in the high-energy ion beam are protons or deuterons greater than 2 MeV. (Item 42) 24. The system of claim 23, wherein the HEIB target can be exposed to the high-energy ion beam for at least a total of 24 hours longer before destruction when the backing component is attached to the bottom surface of the HEIB target compared to when the HEIB target is not attached to the backing component. (Item 43) 24. The system of claim 23, wherein the HEIB target can be exposed to the high-energy ion beam for at least a total of 7 days longer before destruction when the backing component is attached to the bottom surface of the HEIB target compared to when the HEIB target is not attached to the backing component. (Item 44) 1. A method for generating neutrons, the method comprising: a) inserting both the HEIB target and the target backing according to any one of items 1 to 22, or the ion beam target assembly according to any one of items 23 to 43, into a target chamber of an ion beam accelerator system; b) using the ion accelerator system to generate a high-energy ion beam, whereby the high-energy ion beam strikes the HEIB target, thereby generating neutrons; A method comprising: (Item 45) c) collecting at least some of the neutrons. (Item 46) Item 45. The method according to item 44, wherein step b) is carried out continuously for at least 2 days without destruction of the HEIB target. (Item 47) Item 45. The method of item 44, wherein step b) is performed continuously for at least 14 days without destruction of the HEIB target. (Item 48) a) an ion source configured to produce an ion beam; b) an accelerator operably coupled to the ion source and configured to receive the ion beam and accelerate the ion beam to produce an accelerated ion beam; c) a target chamber comprising a target retention mechanism, said target retention mechanism comprising: i) holding a target that generates neutrons when struck by the accelerated ion beam and becomes a radioactive target over time; ii) allowing the radioactive target to be removed from the target chamber with a long-handled tool, the long-handled tool preventing a user of the long-handled tool from being irradiated; a target chamber configured to perform A system comprising: (Item 49) a) inserting a first target of a set of at least two targets into an ion beam accelerator; b) operating the ion beam accelerator for a length of time such that an ion beam strikes the first target, thereby generating neutrons and causing the first target to become a first radioactive target; c) removing the first radioactive target from the ion beam accelerator; d) inserting a second target of the set of at least two targets into the ion beam accelerator; e) operating the ion beam accelerator for a length of time such that an ion beam strikes the second target, thereby generating neutrons and causing the second target to become a second radioactive target; f) identifying that the radioactive first target has cooled over time to become substantially or completely non-radioactive to produce a cooled first target, and inserting the cooled first target into the ion beam accelerator; g) operating the ion beam accelerator for a length of time such that an ion beam strikes the cooled first target, thereby generating neutrons and causing the first cooled target to become a radioactive first target again; A method comprising: (Item 50) Item 49. The method of item 49, wherein the at least two targets are at least five targets including the first target and the second target, and a third target, a fourth target, and a fifth target, and step a) and step b) are repeated using the third target, then the fourth target, then the fifth target. (Item 51) Item 50. The method of item 49, wherein steps f) and g) are repeated with the second target, the third target, the fourth target, and the fifth target after each has cooled. (Item 52) 50. The method of claim 49, wherein the at least two targets are at least 10 targets. (Item 53) a) an ion source configured to produce an ion beam; b) an accelerator operably coupled to the ion source and configured to receive the ion beam and accelerate the ion beam to produce an accelerated ion beam; c) a target chamber configured to receive the accelerated ion beam; and d) a targeting mechanism, said targeting mechanism comprising: i) holding a plurality of targets, each target producing neutrons when struck by the accelerated ion beam within the target chamber; ii) holding one of the plurality of targets at a first position inside the target chamber and in a path of the accelerated ion beam, and holding the remaining targets outside the target chamber; iii) moving the target at the first location to a location outside the target chamber and moving one of the remaining targets to the first location inside the target chamber; a retargeting mechanism configured to: A system comprising: (Item 54) Item 54. The system of item 53, wherein at least one of the plurality of targets is at a location outside the chamber that allows any accumulated radiation to substantially or completely dissipate when not at the first location. (Item 55) Item 54. The system of item 53, wherein at least one of the plurality of targets, when not at the first position, can be removed from the system without stopping or disrupting operation of the accelerated ion beam. (Item 56) Item 54. The system of item 53, wherein the target changing mechanism comprises a carousel, a turret, or a magazine. (Item 57) Item 54. The system of item 53, wherein at least one of the plurality of targets is automatically deposited in the radiation container when not at the first location. (Item 58) Item 54. The system of item 53, wherein the target changing mechanism is further configured to allow one or more additional targets to be added and held by the target changing mechanism without stopping or interrupting the operation of the accelerated ion beam. (Item 59) 1. A device comprising a target changing mechanism for an ion beam accelerator having a target chamber, the target changing mechanism comprising: a) holding a plurality of targets, each target producing neutrons when struck by an accelerated ion beam within the target chamber; b) holding one of the plurality of targets at a first position inside the target chamber and in a path of the accelerated ion beam, and holding the remaining targets outside the target chamber; c) moving the target at the first location to a location outside the target chamber and moving one of the remaining targets to the first location inside the target chamber; A device configured to: (Item 60) Item 60. The device of item 59, wherein at least one of the targets comprises i) a first layer comprising a first metal and ii) a second layer comprising a second metal different from the metal used in the first layer, wherein the metals for the first layer and the second layer are selected from the group consisting of beryllium, uranium, lithium, tungsten, and tantalum. (Item 61) 60. The device, system, or method of any one of items 1-59, wherein any of the target, target retention mechanism, or target chamber comprises or further comprises aluminum, vanadium, aluminum bronze, aluminum-based braze, or any combination thereof. (Item 62) 61. The device, system, or method of any one of items 1-60, further comprising a brazing material, welding material, and / or at least one fastener comprised of aluminum, vanadium, aluminum bronze, aluminum-based braze, or any combination thereof. [Brief explanation of the drawings]

[0022] [Figure 1A]1A shows an exemplary schematic diagram of a cross section of an ion beam target assembly comprised of a high-energy ion beam target (e.g., comprised of beryllium) mounted on a high-hydrogen-diffusive metal target backing (e.g., comprised of palladium) with an open space. The ion beam target assembly is shown mounted on a cooled substrate (e.g., comprised of copper or aluminum). [Figure 1B] FIG. 1B shows a close-up cross section of the exemplary ion beam target assembly of FIG. 1A, showing a close-up detail of the open space in the target backing. DETAILED DESCRIPTION OF THE INVENTION

[0023] (Detailed explanation) Provided herein are systems, devices, articles, and methods for generating neutrons, which use a high-energy ion beam target (HEIB target) and a target backing configured to contact the bottom surface of the HEIB target (e.g., to create an ion beam target assembly). In certain embodiments, the HEIB target has a thickness less than the penetration depth of protons in a high-energy ion beam striking the target. In some embodiments, the HEIB target comprises a metal selected from beryllium, uranium, lithium, lithium compounds, tungsten, and tantalum. In certain embodiments, the ion beam comprises protons. In other embodiments, the ion beam comprises deuterons. In certain embodiments, the target backing comprises a high-hydrogen diffusion metal (e.g., palladium), has open spaces distributed throughout for reduced proton or deuteron diffusion distance, and has a shape and thickness such that all or virtually all protons or deuterons passing through the HEIB target are stopped. Also provided herein are systems, devices, and methods for modifying targets in ion beam accelerator systems. The individual or collective ion beam target assemblies (and their components) may be applied, for example, to any non-reactive source of high-energy neutrons. Embodiments of the present technology may be employed in high-energy ion beam generator systems such as those described in U.S. Patent Publication Nos. 2011 / 0096887, 2012 / 0300890, U.S. Patent Application Nos. 15 / 873,664, and 2016 / 0163495, and U.S. Patent Nos. 8,837,662 and 9,024,261, all of which are incorporated herein by reference in their entireties.

[0024] Non-limiting embodiments of articles, devices, and systems include the following: A beryllium (or uranium, lithium, lithium compounds, tungsten, or tantalum) target is bonded to a thin, corrugated palladium target backing (e.g., a sheet) that is bonded to a water-cooled substrate (e.g., copper or aluminum). The thickness of the beryllium is less than the penetration depth of the incident protons. The thickness of the target backing is sufficient so that all of the protons or deuterons are stopped by the target backing. The target backing may be grooved, for example, in an arbitrary pattern such that most of the palladium metal is a relatively short distance from the surface. The diffusion and solubility of hydrogen in palladium are very high. Excess hydrogen (protons) implanted in palladium can diffuse into nearby grooves and leave the system before damage occurs to the palladium. The lifetime is very long, limited only by small damage events to the Be. The thickness of the palladium and the relative amount of grooves are used to adjust the temperature of the palladium under irradiation to increase the diffusion rate. Target destruction may not result in a vacuum breach. Any material with relatively high hydrogen diffusivity may be used in place of palladium. Suitable performance may be obtained using significantly cheaper materials such as titanium, vanadium, niobium, and zirconium. Besides grooving, any mechanism that reduces the hydrogen diffusion distance may also be used. For example, proton open-cell palladium (or other materials) produced from powder metallurgy or other techniques may also be used.

Claims

1. A system comprising: an ion source configured to produce an ion beam; an accelerator operably coupled to the ion source and configured to receive the ion beam and accelerate the ion beam to produce an accelerated ion beam; a target chamber configured to receive the accelerated ion beam; a plurality of targets, each of the plurality of targets producing neutrons when struck by the accelerated ion beam in the target chamber; A targeting mechanism, the targeting mechanism comprising: i) holding said plurality of targets; ii) holding one of the plurality of targets at a first position inside the target chamber and in a path of the accelerated ion beam, while holding the remaining targets outside the target chamber; iii) moving the target at the first location to a location outside the target chamber and moving one of the remaining targets to the first location inside the target chamber; a targeting mechanism configured to: wherein at least one of the plurality of targets, when not in the first position, is at a location outside the chamber that allows any accumulated radiation to substantially or completely dissipate.

2. The system described in claim 1, wherein at least one of the plurality of targets can be removed from the system when not in the first position without stopping or interfering with the operation of the accelerated ion beam.

3. The system described in claim 1, wherein the target changing mechanism comprises a carousel, a turret, or a magazine.

4. The system described in claim 1, wherein at least one of the plurality of targets is automatically deposited in the radiation container when not in the first position.

5. The system described in claim 1, wherein the target changing mechanism is further configured to allow one or more additional targets to be added and held by the target changing mechanism without stopping or interfering with the operation of the accelerated ion beam.

6. The system described in claim 1, wherein the plurality of targets includes a first target, the first target including a metal, the metal being selected from the group consisting of beryllium, uranium, lithium, tungsten, and tantalum.

7. The system described in claim 6, wherein the metal has a thickness in the range of 2 mm to 25 mm and a diameter in the range of 25 mm to 150 mm.

8. The system described in claim 6, wherein the first target further includes a backing bonded to the metal, the backing having a plurality of open spaces.

9. The system described in claim 8, wherein the plurality of open spaces are gas or vacuum filled.

10. The system described in claim 8, wherein the plurality of open spaces are selected from pores, grooves, holes, corrugations, channels, open cells, honeycomb cells, irregular openings, or any combination thereof.

11. The system described in claim 8, wherein the backing is selected from the group consisting of palladium, titanium, vanadium, niobium, and zirconium.

12. The system described in claim 11, wherein the thickness of the backing is in the range of 2 mm to 10 mm.

13. The system of claim 8, wherein the backing comprises a vanadium core coated with a thin film of palladium.

14. The system described in claim 8, wherein the first target further includes a substrate bonded to the backing, the backing being positioned between the metal and the substrate.

15. The system of claim 14, wherein the substrate comprises copper, aluminum, or a combination thereof.

16. The system described in claim 1, wherein the ion beam includes protons or deuterons having an energy of 2 MeV or more.

17. The system of claim 1, wherein at least one of the plurality of targets, the target holding mechanism, or the target chamber comprises aluminum, vanadium, aluminum bronze, aluminum-based brazing, or any combination thereof.

18. The system of claim 1, wherein the target holding mechanism and the target chamber are constructed from aluminum, vanadium, aluminum bronze, aluminum-based brazing, or any combination thereof.

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