Ion beam target assembly for neutron generation

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 Jun. 6, 2018, which is hereby incorporated 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 generate 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 strikes the target. In certain embodiments, the target backing comprises a high-hydrogen diffusion metal (e.g., palladium) and has open spaces dispersed throughout for a reduced proton or deuteron diffusion distance and has a shape and thickness such that all or substantially all of the protons or deuterons passing through the HEIB target are stopped. Also provided herein are systems, devices, and methods for changing a target within an ion beam accelerator system.

Background Art

[0003] (Background) Known methods for producing neutrons are to collide high-energy (>2 MeV) protons with a beryllium (Be) target. Beryllium needs to be cooled to prevent melting and / or thermal deformation. A typical shape is a Be disk brazed to a water-cooled block or a Be block sealed in a holder and directly cooled on the back side (away from the beam) by water or other fluid. A consistent problem with this method is that the material into which the protons are embedded is embrittled and expanded by the embedded protons. Ultimately, this results in direct physical degradation (sputtering) of the target. A typical limit of the embedded dose before visible target damage is about 10 18 protons / cm2 In a high-power density system, visible damage can occur with exposures of minutes.

[0004] One way to mitigate this problem is to make the Be target thinner than the proton stopping distance so that relatively fewer protons are deposited in the Be. The depth to which protons penetrate a material depends on the proton energy and the material in which the protons are deposited. In the case of a directly 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. The target lifetime can be probabilistic and failure can result in a catastrophic flood 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 sputtering damage. However, by selecting a substrate material that can absorb a relatively large amount of hydrogen, the target lifetime can be increased. For example, tantalum can hold about 100 to 1000 times the amount of hydrogen as Be before damage. In a high-power system, this can result in a target lifetime measured in over 100 hours, but is still finite. In such cases, the material is activated by the creation of a high neutron flux. What is needed is a design that can be optimized to reduce the production of long-lived radioisotopes. This allows for easier and safer operation and maintenance of the target, as well as higher uptime for the device in which the target is utilized.

Summary of the Invention

Means for Solving the Problems

[0005] (Overview) Provided herein are systems, devices, products, and methods for generating neutrons that 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 generate an ion beam target assembly). In certain embodiments, the HEIB target has a thickness that is less than the penetration depth of protons in the high energy ion beam that strikes 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) and has open spaces dispersed throughout for a reduced proton or deuteron diffusion distance, and has a shape and thickness such that all or substantially all of the protons or deuterons passing through the HEIB target are stopped. In some embodiments, the high energy ion beam comprises hydrogen ions or deuterium ions. Also provided herein are systems, devices, and methods for changing a target within an ion beam accelerator system.

[0006] In some embodiments, provided herein is a system, the system comprising: a) a high energy ion beam target (HEIB target) having a top surface and a bottom surface, the HEIB target generating 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 diffusion metal (HHDM), the target backing having open spaces dispersed throughout such that the proton diffusion distance or the deuteron diffusion distance is reduced across the target backing compared to when the target backing was a solid piece without open spaces, the target backing being 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 an ion beam target assembly, the ion target beam assembly comprising: a) a high energy ion beam target (HEIB target) having a top surface and a bottom surface, the HEIB target generating 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, the high energy ion beam target; and b) a target backing comprising a high hydrogen diffusion metal (HHDM), the target backing having open spaces dispersed throughout such that the proton or deuteron diffusion distance is reduced throughout the target backing as compared to when the target backing was a solid piece without open spaces, the target backing being 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 is a method of generating neutrons, the method comprising: a) inserting both the HEIB target and the target backing (in contact with each other), or the ion beam target assembly, into the target chamber of an ion beam accelerator system as described herein; and b) generating a high energy ion beam using an ion accelerator system such that the high energy ion beam impinges on 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 carried out 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 carried out continuously for at least 14 days without destruction of the HEIB target.

[0009] In some embodiments, the open space within the target backing is 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 system and product 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 the metal used in the first layer and 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, it is adopted to use a plurality of layers within the target to decelerate the ion beam when the ion beam traverses the target, which decelerates the ion beam from its original energy to a lower energy (largely due to electron interactions). In some embodiments, using different materials at different lengths (energies) along the beam path enables 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 the target backing are generally disk-shaped, square, octagonal, elliptical, rectangular, and have the same diameter. The HEIB target is designed such that the high-energy ion beam hits the target at an incident angle of 90 degrees or an incident angle other than 90 degrees (e.g., 45 degrees... 60 degrees... 30 degrees, etc.), which has the effect of increasing the range where the beam hits the target and thus reducing the power density of the beam by a geometric amount. In some embodiments, such a target has an elliptical, rectangular, or other elongated shape in the direction of the target's inclination.

[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 ortho - 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 composed of 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 certain embodiments, the target backing is composed of a solid vanadium core coated with a thin film of palladium.

[0014] In additional embodiments, the system and product further comprise a target chamber. In certain embodiments, the 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 positioned within the target chamber. In other embodiments, the system and product 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 produce 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 that includes 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 breach of the vacuum in the accelerator.

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

[0016] In additional embodiments, provided herein is a system, the 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, the 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) enable the radioactive target to be removed from the target chamber using at least one long-handled tool, the long-handled tool preventing the user of the long-handled tool from being irradiated.

[0017] In certain embodiments, provided herein is a method, the method 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 the ion beam strikes the first target, thereby generating neutrons and turning the first target into 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 the ion beam strikes the second target, thereby generating neutrons and turning the second target into a second radioactive target; f) identifying that the first radioactive target has cooled over time to become substantially or completely non-radioactive so as to produce a cooled first target, and inserting the cooled first target into the ion beam accelerator; and g) operating the ion beam accelerator for a length of time such that the ion beam strikes the cooled first target, thereby generating neutrons and turning the first cooled target back into 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 after each of the second target, the third target, the fourth target, and the fifth target has been cooled. In additional embodiments, the at least two targets are at least ten targets.

[0019] In some embodiments, provided herein is a system, the 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; c) a target chamber configured to receive the accelerated ion beam; and d) a target changer, the target changer comprising: i) holding a plurality of targets, each target being configured to generate neutrons when the accelerated ion beam is applied thereto within the target chamber; ii) holding one of the plurality of targets at a first position inside the target chamber and within the path of the accelerated ion beam, and holding the remaining targets outside the target chamber; and iii) being configured to move the target at the first position to a position outside the target chamber and move one of the remaining targets to the first position inside the target chamber. In a further embodiment, at least one of the plurality of targets is located at a position outside the chamber that allows any accumulated radiation to dissipate substantially or completely when not in the first position. In other embodiments, at least one of the plurality of targets can be removed from the system without stopping or interfering with the operation of the accelerated ion beam when not in the first position. In certain embodiments, the target changer comprises a carousel, turret, or magazine (which allows the target to be moved without human intervention or without human intervention other than activating the target changer). In certain embodiments, at least one of the plurality of targets is automatically deposited into a radiation container when not in the first position. In additional embodiments, the target changer is further configured to allow one or more additional targets to be added and held by the target changer without stopping or interfering with the operation of the accelerated ion beam.

[0020] In certain embodiments, provided herein is a device comprising 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 target generating neutrons when bombarded with an accelerated ion beam within the target chamber; b) hold one of the plurality of targets at a first position inside the target chamber and within the 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 the first position inside the target chamber.

[0021] In certain embodiments, the targets, target holding mechanisms, target chambers, brazing and / or welding materials, fixtures, and all other components are selected to minimize the production of long-lived (e.g., 120-day half-life) radioisotopes resulting from neutron capture and other neutron reactions. The use of these materials enables easier and safer target handling and maintenance, as well as higher uptime for the devices in which they are used. Additionally, the reduction in target activity enables easier licensing 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) A system, the system comprising: a) A high-energy ion beam target (HEIB target) comprising a metal and having a top surface and a bottom surface, wherein the metal is selected from the group consisting of beryllium, uranium, lithium, tungsten, and tantalum, the high-energy ion beam comprising protons and / or deuterons, the HEIB target generating neutrons when exposed to the high-energy ion beam, The HEIB target is a high-energy ion beam target having a thickness between the top surface and the bottom surface that is smaller than the penetration depth of protons or heavy protons in the high-energy ion beam, b) a target backing comprising a high hydrogen diffusion metal (HHDM), The target backing has open spaces dispersed throughout, whereby the proton or heavy proton diffusion distance is reduced throughout the target backing compared to the case where the target backing is 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 heavy protons in the high-energy ion beam passing through the HEIB target are stopped by the target backing, A system comprising. (Item 2) The open space is selected from pores, grooves, holes, corrugations, channels, open cells, honeycomb cells, irregular openings, or any combination thereof, for the system according to item 1. (Item 3) 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, for the system according to item 1. (Item 4) c) The system according to item 1, further comprising a cooled substrate. (Item 5) The target backing is attached or configured to be attached to the cooled substrate, for the system according to item 4. (Item 6) The HEIB target of the system according to item 1 comprises: i) a first layer comprising the metal; and ii) a second layer comprising a metal different from that used in the first layer and selected from the group consisting of beryllium, uranium, lithium, tungsten, and tantalum. (Item 7) The cooled substrate of the system according to item 4 comprises copper and / or aluminum. (Item 8) The HEIB target of the system according to item 1 has a thickness between 2 mm and 25 mm and a diameter between 25 mm and 150 mm. (Item 9) The thickness of the target backing of the system according to item 1 is between 2 mm and 10 mm. (Item 10) The target backing of the system according to item 1 comprises a solid vanadium core coated with a thin film of palladium. (Item 11) At least 94% of the HEIB target of the system according to item 1 is the metal. (Item 12) The high hydrogen diffusion metal (HHDM) of the system according to item 1 comprises palladium. (Item 13) The high hydrogen diffusion metal (HHDM) of the system according to item 1 is selected from the group consisting of palladium, titanium, vanadium, niobium, zirconium, and any combination thereof. (Item 14) At least 94% of the target backing of the system according to item 1 is the high hydrogen diffusion metal (HHDM). (Item 15) The system according to item 1 further comprises a target chamber. (Item 16) The target backing is positioned on or attached to the bottom surface of the HEIB target, thereby generating an ion beam target assembly, and the ion beam target assembly is located within the target chamber, of the system according to item 15. (Item 17) c) an ion source configured to generate 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 generate the high-energy ion beam, the system according to item 1. (Item 18) The target backing is attached to the bottom surface of the HEIB target, thereby generating an ion beam target assembly, and the system further comprises e) a target chamber including the ion beam target assembly, the system according to item 17. (Item 19) 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, the system according to item 18. (Item 20) The protons or deuterons in the high-energy ion beam are protons or deuterons greater than 2 MeV, the system according to item 1. (Item 21) 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 positioned without contacting the backing component, the system according to item 1. (Item 22) 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 positioned without contacting the backing component, the system according to item 1. (Item 23) A product, the product 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, wherein the metal is selected from the group consisting of beryllium, uranium, lithium, tungsten, and tantalum, wherein the high-energy ion beam comprises protons and / or deuterons, wherein the HEIB target generates neutrons when exposed to the high-energy ion beam, wherein the HEIB target has a thickness between the top surface and the bottom surface, and the thickness between the top surface and the bottom surface is smaller than the penetration depth of the protons or deuterons in the high-energy ion beam, a high-energy ion beam target, ii) A target backing comprising a high-hydrogen diffusion metal (HHDM), wherein the target backing has open spaces dispersed throughout, whereby the proton or deuteron diffusion distance is reduced throughout the target backing compared to when the target backing was a solid piece without the open spaces, wherein the target backing is attached to the bottom surface of the HEIB target, wherein 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 target backing Comprising a product. (Item 24) The system according to item 23, wherein the open space is selected from pores, grooves, holes, corrugations, channels, open cells, honeycomb cells, irregular openings, or any combination thereof. (Item 25) The system according to item 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 according to item 23, further comprising a cooled substrate. (Item 27) The HEIB target of the system according to item 23 comprises: i) a first layer comprising the metal; and ii) a second layer comprising a metal different from that used in the first layer and selected from the group consisting of beryllium, uranium, lithium, tungsten, and tantalum. (Item 28) The cooled substrate of the system according to item 26 comprises copper and / or aluminum. (Item 29) The HEIB target of the system according to item 23 has a thickness between 2 mm and 25 mm and a diameter between 25 mm and 150 mm. (Item 30) The thickness of the target backing of the system according to item 23 is between 2 mm and 10 mm. (Item 31) The target backing of the system according to item 23 comprises a core of solid vanadium coated with a thin film of palladium. (Item 32) At least 95% of the HEIB target of the system according to item 23 is the metal. (Item 33) The high hydrogen diffusion metal (HHDM) of the system according to item 23 comprises palladium. (Item 34) The high hydrogen diffusion metal (HHDM) of the system according to item 23 is selected from the group consisting of palladium, titanium, vanadium, niobium, zirconium, and any combination thereof. (Item 35) At least 95% of the target backing of the system according to item 23 is the high hydrogen diffusion metal (HHDM). (Item 36) b) The system according to item 23, further comprising a target chamber. (Item 37) The ion beam target assembly of the system according to item 36 is located within the target chamber. (Item 38) b) an ion source configured to generate an ion beam; and c) an accelerator operably coupled to the ion source, configured to receive the ion beam and accelerate the ion beam to generate the high-energy ion beam, the system according to item 23. (Item 39) e) the system according to item 38, further comprising a target chamber including the ion beam target assembly. (Item 40) 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 breach of vacuum in the accelerator, the system according to item 39. (Item 41) The protons or deuterons in the high-energy ion beam are protons or deuterons greater than 2 MeV, the system according to item 23. (Item 42) 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, the system according to item 23. (Item 43) 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, the system according to item 23. (Item 44) A method of generating neutrons, the method comprising: a) inserting either both the HEIB target and 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) generating a high-energy ion beam using the ion accelerator system, such that the high-energy ion beam hits the HEIB target, thereby generating neutrons A method comprising the steps of: (Item 45) The method according to item 44, further comprising c) collecting at least some of the neutrons (Item 46) 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) The method according to item 44, wherein step b) is carried out 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, configured to receive the ion beam and accelerate the ion beam to produce an accelerated ion beam c) a target chamber comprising a target holding mechanism, the target holding mechanism being configured to i) hold a target that generates neutrons when irradiated with the accelerated ion beam and becomes a radioactive target over time ii) enable the radioactive target to be removed from the target chamber using a long-handled tool, the long-handled tool preventing the user of the long-handled tool from being irradiated A target chamber configured to perform the above steps A system comprising the above components (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 period of time such that the ion beam hits the first target, thereby generating neutrons and making the first target a first radioactive target c) removing the first radioactive target from the ion beam accelerator d) inserting a second target of the at least two sets of targets into the ion beam accelerator; e) operating the ion beam accelerator for a period of time such that an ion beam hits the second target, thereby generating neutrons and converting the second target into a second radioactive target; f) identifying that the first radioactive target has cooled over time to become substantially or completely non-radioactive so as 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 period of time such that an ion beam hits the cooled first target, thereby generating neutrons and converting the cooled first target back into a radioactive first target A method comprising the above. (Item 50) 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 steps a) and b) are repeated using the third target, then the fourth target, then the fifth target, the method according to item 49. (Item 51) Steps f) and g) are repeated after each of the second target, the third target, the fourth target, and the fifth target has been cooled, the method according to item 49. (Item 52) The at least two targets are at least ten targets, the method according to item 49. (Item 53) a) an ion source configured to generate an ion beam; b) an accelerator operably coupled to the ion source, configured to receive the ion beam and accelerate the ion beam to generate an accelerated ion beam; c) a target chamber configured to receive the accelerated ion beam; d) A target changing mechanism, wherein the target changing mechanism is i) to hold a plurality of targets, each target generating neutrons when irradiated with the accelerated ion beam within the target chamber; ii) to hold one of the plurality of targets at a first position inside the target chamber and within the path of the accelerated ion beam, and to hold the remaining targets outside the target chamber; iii) to move the target at the first position to a position outside the target chamber and to move one of the remaining targets to the first position inside the target chamber; A target changing mechanism configured to perform the above; A system comprising the above. (Item 54) The system according to item 53, wherein at least one of the plurality of targets is located at a position outside the chamber that allows any accumulated radiation to dissipate substantially or completely when not in the first position. (Item 55) The system according to item 53, wherein at least one of the plurality of targets can be removed from the system without stopping or interfering with the operation of the accelerated ion beam when not in the first position. (Item 56) The system according to item 53, wherein the target changing mechanism comprises a carousel, turret or magazine. (Item 57) The system according to item 53, wherein at least one of the plurality of targets is automatically deposited into a radiation container when not in the first position. (Item 58) The system according to 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 interfering with the operation of the accelerated ion beam. (Item 59) A device comprising a target changing mechanism for an ion beam accelerator having a target chamber, wherein the target changing mechanism is a) to hold a plurality of targets, each target generating neutrons when irradiated with an accelerated ion beam within the target chamber; b) to hold one of the plurality of targets at a first position inside the target chamber and in the path of the accelerated ion beam, and to hold the remaining targets outside the target chamber; c) to move the target at the first position to a position outside the target chamber and to move one of the remaining targets to the first position inside the target chamber. A device configured to perform the above. (Item 60) 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. The device according to item 59. (Item 61) Any one of the devices, systems, or methods according to items 1 to 59, wherein any one of the target, the target holding mechanism, or the target chamber comprises or further comprises aluminum, vanadium, aluminum bronze, aluminum-based brazing, or any combination thereof. (Item 62) Any one of the devices, systems, or methods according to items 1 to 60, further comprising a brazing material, a welding material, and / or at least one fixture composed of aluminum, vanadium, aluminum bronze, aluminum-based brazing, or any combination thereof.

Brief Description of the Drawings

[0022]

Figure 1A

Figure 1B

DETAILED DESCRIPTION OF THE INVENTION

[0023] (Detailed Description) Provided herein are systems, devices, products, 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 generate 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 applied to 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) and has open spaces dispersed throughout for a reduced proton or deuteron diffusion distance, and has a shape and thickness such that all or substantially all of the protons or deuterons passing through the HEIB target are stopped. Also provided herein are systems, devices, and methods for changing a target in an ion beam accelerator system. Individual or collective ion beam target assemblies (and their components) can be applied, for example, to any non-reactive source of high energy neutrons. Embodiments of this technology can be employed in high energy ion beam generator systems such as those described in U.S. Patent Publications Nos. 2011 / 0096887, 2012 / 0300890, U.S. Patent Application No. 15 / 873,664, and 2016 / 0163495, and U.S. Patents Nos. 8,837,662 and 9,024,261, all of which are hereby incorporated by reference in their entirety.

[0024] Non-limiting embodiments of articles, devices, and systems include the following. A beryllium (or uranium, lithium, lithium compound, tungsten, or tantalum) target is joined to a thin, corrugated palladium target backing (e.g., a sheet) that is joined 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 to stop all of the protons or deuterons. The target backing is grooved, for example, in any pattern such that most of the palladium metal is at a relatively short distance from the surface. The diffusion and solubility of hydrogen in palladium are very high. Excess hydrogen (protons) implanted in the palladium can diffuse into the neighboring grooves and leave the system before damage occurs to the palladium. The lifetime is very long and is limited only by small damage events to the Be. The thickness of the palladium and the relative amount of grooving 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 having a relatively high hydrogen diffusivity can be used in place of palladium. Suitable performance can be achieved using significantly less expensive materials such as titanium, vanadium, niobium, zirconium, etc. In addition to grooving, any mechanism that reduces the diffusion distance of hydrogen can also be used. For example, a proton open-cell type palladium (or other material) created from powder metallurgy or other techniques can also be used.

Claims

1. Inserting a first target of at least two sets of targets into an ion beam accelerator; Operating the ion beam accelerator for a length of time such that an ion beam hits the first target, thereby generating neutrons and making the first target a first radioactive target; Removing the first radioactive target from the ion beam accelerator; Inserting a second target of the at least two sets of targets into the ion beam accelerator; Operating the ion beam accelerator for a length of time such that an ion beam hits the second target, thereby generating neutrons and making the second target a second radioactive target; Identifying that the first radioactive target has cooled over time to become substantially or completely non-radioactive so as to produce a cooled first target, and inserting the cooled first target into the ion beam accelerator; Operating the ion beam accelerator for a length of time such that an ion beam hits the cooled first target, thereby generating neutrons and making the first cooled target a radioactive first target again; including, the first target includes a metal, and the metal is selected from the group consisting of beryllium, uranium, lithium, tungsten, and tantalum; the first target further includes a backing bonded to the metal, and the backing has a plurality of open spaces, a method.

2. The method further includes identifying that the second radioactive target has cooled over time to become substantially or completely non-radioactive so as to produce a cooled second target, and inserting the cooled second target into the ion beam accelerator, according to the method of claim 1.

3. The at least two targets include the first target, the second target, and a third target, and the method further includes inserting the third target into the ion beam accelerator and operating the ion beam accelerator for a length of time such that an ion beam hits the third target, thereby generating neutrons and making the third target a third radioactive target, according to the method of claim 1.

4. The at least two targets are at least five targets, according to the method of claim 3.

5. The method according to claim 4, wherein the at least two targets are at least 10 targets. **Claim 6** The method according to claim 1, wherein operating the ion beam accelerator for a length of time such that the ion beam hits the first target is carried out continuously for at least 2 days. **Claim 7** The method according to claim 6, wherein operating the ion beam accelerator for a length of time such that the ion beam hits the first target is carried out continuously for at least 14 days. **Claim 8** The method according to claim 1, 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. **Claim 9** The method according to claim 1, wherein the plurality of open spaces are filled with gas or vacuum. **Claim 10** The method according to claim 9, wherein the plurality of open spaces are selected from pores, grooves, holes, waveforms, channels, open cells, honeycomb cells, irregular openings, or any combination thereof. **Claim 11** The method according to claim 9, wherein the backing is selected from the group consisting of palladium, titanium, vanadium, niobium, and zirconium. **Claim 12** The method according to claim 1, wherein the thickness of the backing is in the range of 2 mm to 10 mm. **Claim 13** The method according to claim 1, wherein the backing comprises a core of vanadium coated with a thin film of palladium. **Claim 14** The method according to claim 1, wherein the first target further comprises a substrate bonded to the backing, and the backing is positioned between the metal and the substrate. **Claim 15** The method according to claim 14, further comprising cooling the substrate of the first target with a liquid when the ion beam hits the first target. **Claim 16** The method according to claim 14, wherein the substrate comprises copper and / or aluminum. **Claim 17** The method according to claim 1, wherein the ion beam comprises protons or deuterons having an energy of 2 MeV or more. **Claim 18** The method according to claim 1, wherein inserting the first target, removing the first target, and inserting the second target are carried out by a target changing mechanism.

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