Systems, devices, and methods for reducing and resisting deformation in metallic bodies.

Abstract

To provide systems, devices, and methods for reducing and resisting deformation in metallic bodies. [Solution] A metal body having a lithium layer and a metal substrate is provided. The metal body can exhibit increased resistance to radiation-induced deformation such as blistering. Methods for transitioning the metal body to a more blister-resistant configuration are provided, along with the inventors' methods for reducing or eliminating previously formed blisters. Systems and methods for utilizing the metal body are also disclosed. The subject matter described herein generally relates to systems, devices, and methods for reducing the possibility of deformation formation and / or reducing the size of deformation in a metal body.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application is incorporated herein by reference in whole by "SYSTEMS, DEVICES, AND METHODS" for any purpose. The patent application claims priority to Russian Patent Application No. 2020124384, filed on July 23, 2020, and is titled "FOR DEFORMATION REDUCTION AND RESISTANCE IN METALLIC BODIES".

[0002] The subject matter described herein generally relates to systems, devices, and methods for reducing the possibility of deformation formation and / or reducing the size of deformation in a metallic body. [Background technology]

[0003] There are many applications in which metallic objects are placed in environments where they are exposed to relatively large amounts of charged particle radiation. Examples of these applications include medical treatment (e.g., cancer) and diagnosis, nuclear fusion, space technology, isotope production, hazardous substance detection, assay and imaging of precious metal minerals, and others.

[0004] Exposure to a sufficient amount of charged particle radiation can subject certain types of metal bodies to potentially degradation conditions where the radiation induces the occurrence of deformations within the body. These deformations often take the form of blisters, and the conditions that give rise to such are generally referred to as blistering. Blistering can be caused by the generation of molecular hydrogen gas within these metal bodies. Hydrogen gas can be formed when charged particle radiation such as proton radiation causes metal electrons to recombine and form molecular hydrogen gas. The gas can accumulate within pockets in the metal body (such as incipient bubbles). Continued exposure to radiation can generate additional hydrogen, which grows the gaseous pockets and potentially appears as blisters (such as cracks, protrusions, flakes, and / or other deformations) on or near the surface of the metal body. This form of blistering is generally more characteristic of metals that poorly decompose hydrogen (such as copper, aluminum, molybdenum, iron, silver, tungsten, platinum, and gold) than of metals that decompose hydrogen well (such as alkali, alkaline earth, titanium, tantalum, niobium, vanadium, nickel, and palladium). (See, for example, Badrutdinov et al., In Situ Observations of Blistering of a Metal Irradiated with 2-MeV Protons, Metals 2017, 7, 558.)

[0005] The material deformations caused by such blisters can be significant and, depending on the type of application, can lead to problems. Thus, blistering is generally regarded as an undesirable effect of charged particle radiation exposure.

[0006] Therefore, there is a need for systems, devices, and methods with anti-deformation characteristics such as those that resist blister formation, reduce the likelihood of blister formation, and / or decrease the size of blisters already formed in metal bodies exposed to charged particle radiation. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0007] The present disclosure provides exemplary embodiments of systems and devices that exhibit anti-deformation properties when exposed to charged particle radiation, and methods for imparting those properties to systems and devices. These anti-deformation properties can include an increased resistance to deformation formation or a reduced likelihood of deformation formation when exposed to radiation. These methods also include embodiments that can reduce the size of deformations already formed from radiation exposure and reduce the number of deformations already formed. Methods for manufacturing systems and devices that exhibit these improved anti-deformation properties are also provided, along with the inventors' methods for conditioning manufactured systems and devices so that they exhibit these improved properties. Examples of deformations can include, but are not limited to, blisters induced by the formation of hydrogen gas. Examples of benefits from the foregoing embodiments can include prevention of deformation formation, reduction of the effects of already formed deformations (e.g., recovery or relaxation), extension of the operating life of systems and devices exposed to charged particle radiation, and others.

[0008] Other systems, devices, methods, features, and advantages of the subject matter described herein will be apparent to those skilled in the art upon examination of the following figures and detailed description, or will become apparent to them. All such additional systems, methods, features, and advantages are intended to be included within this description, are within the scope of the subject matter described herein, and are protected by the accompanying claims. Even if a specific listing of these features is not present in the claims, in no way should the features of the exemplary embodiments be construed as limiting the appended claims. The present invention provides, for example, the following. (Item 1) A method of operating a beam system having a target comprising a lithium layer and a metal substrate, the method comprising: (a) exposing the target to charged particle radiation such that the target emits neutrons and a plurality of blisters are formed in the target; (b) Exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced in quantity and / or size. Methods that include... (Item 2) The method according to item 1, wherein the charged particle radiation is a proton beam. (Item 3) (b) The step of exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced in quantity and / or size is performed per square centimeter (cm -2 ) at least 0.5 × 10 19 The method according to item 1, comprising the step of exposing the target to the proton energy fluence. (Item 4) (b) The method of item 1, wherein the step of exposing the target to further charged particle radiation includes exposing the target to further charged particle radiation until the amount of blister is reduced by an order of magnitude. (Item 5) Neutrons are at least 1 × 10⁻¹⁶ per second in steps (a) and (b). 12 The method according to item 1, wherein a neutron is emitted at a first rate. (Item 6) (a) The method of item 1, wherein the step of exposing the target to charged particle radiation such that the target emits neutrons and a plurality of blisters are formed in the target further comprises the step of applying the emitted neutrons to a human patient. (Item 7) (b) The method of item 1, wherein the step of exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced in quantity and / or size further comprises the step of applying the emitted neutrons to a human patient. (Item 8) The emitted neutrons react with p+ 7 Li→n+ 7 The method according to item 1, which is produced by the lithium layer according to Be. (Item 9) The method according to item 1, further comprising the step of performing (a) and (b) as part of a boron neutron capture therapy (BNCT) procedure. (Item 10) The method according to item 1, wherein the charged particle radiation is in the form of a beam, and the target is exposed to the charged particle radiation in steps (a) and (b) while the beam is moved across the surface of the target in a direction transverse to the direction of propagation of the beam. (Item 11) (b) The method of item 1, further comprising the step of exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced in quantity and size. (Item 12) (b) The method of item 1, further comprising the step of exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced only in size. (Item 13) The method according to item 1, wherein the metal substrate is copper. (Item 14) The lithium layer is in contact with the copper substrate, as described in item 13. (Item 15) The lithium layer is formed directly on the copper bulk substrate, as described in item 13. (Item 16) The lithium layer has a thickness in the range of 1 micron to 300 microns, according to the method of item 1. (Item 17) The charged particle radiation is the method described in item 1, having an energy in the range of 1.9 MeV to 3.0 MeV. (Item 18) A method for operating a beam system having a target comprising a lithium layer and a metal substrate, wherein the method is (a) Exposing the target to charged particle radiation such that the target emits neutrons and a plurality of blisters are formed in the target, (b) exposing the target to further charged particle radiation such that the target emits neutrons and the lithium compound layer is formed to a size sufficient to reduce the plurality of blisters in quantity and / or size between the lithium layer and the metal substrate; A method comprising. (Item 19) The method according to item 18, wherein the charged particle radiation is a proton beam. (Item 20) (b) The step of exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced in quantity and / or size comprises exposing the target to a proton energy fluence of at least 0.5×10 -2 per square centimeter (cm 19 ). The method according to item 18. (Item 21) (b) The step of exposing the target to further charged particle radiation comprises exposing the target to further charged particle radiation until the quantity of the blisters is reduced by one order of magnitude. The method according to item 18. (Item 22) The neutrons are emitted at a first rate of at least 1×10 12 neutrons per second in steps (a) and (b). The method according to item 18. (Item 23) (a) The step of exposing the target to charged particle radiation such that the target emits neutrons and a plurality of blisters are formed in the target further comprises applying the emitted neutrons to a human patient. The method according to item 18. (Item 24) (b) The step of exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced in quantity and / or size further comprises applying the emitted neutrons to a human patient. The method according to item 18. (Item 25) The emitted neutrons are from the reaction p+ 7 Li→n+7 The method according to item 18, which is produced by the lithium layer according to Be. (Item 26) The method according to item 18, further comprising the step of performing (a) and (b) as part of a boron neutron capture therapy (BNCT) procedure. (Item 27) The method according to item 18, wherein the charged particle radiation is in the form of a beam, and the target is exposed to the charged particle radiation in steps (a) and (b) while moving the beam across the surface of the target in a direction transverse to the direction of propagation of the beam. (Item 28) (b) The method of item 18, further comprising the step of exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced in quantity and size. (Item 29) (b) The method of item 18, further comprising the step of exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced only in size. (Item 30) The method according to item 18, wherein the metal substrate is copper and the lithium compound layer is a lithium copper compound. (Item 31) The lithium layer having a thickness in the range of 1 micron to 300 microns, according to the method of item 18. (Item 32) The charged particle radiation is the method described in item 18, having an energy in the range of 1.9 MeV to 3.0 MeV. (Item 33) A method for operating a beam system having a target comprising a lithium layer and a metal substrate, wherein the method is (a) Exposing the target to charged particle radiation such that the target emits neutrons and a plurality of blisters are formed in the target, (b) Exposing the target to further charged particle radiation such that the target emits neutrons and the metal substrate transitions from a crystalline state to an amorphous state sufficient to reduce the plurality of blisters in quantity and / or size. Methods that include... (Item 34) The method according to item 33, wherein the charged particle radiation is a proton beam. (Item 35) (b) The step of exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced in quantity and / or size is performed per square centimeter (cm -2 ) at least 0.5 × 10 19 The method according to item 33, comprising the step of exposing the target to the proton energy fluence. (Item 36) (b) The method of item 33, wherein the step of exposing the target to further charged particle radiation includes exposing the target to further charged particle radiation until the amount of blister is reduced by an order of magnitude. (Item 37) Neutrons are at least 1 × 10⁻¹⁶ per second in steps (a) and (b). 12 The method according to item 33, wherein a neutron is emitted at a first rate. (Item 38) (a) The method of item 33, wherein the step of exposing the target to charged particle radiation such that the target emits neutrons and a plurality of blisters are formed in the target further comprises the step of applying the emitted neutrons to a human patient. (Item 39) (b) The method of item 33, wherein the step of exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced in quantity and / or size further comprises the step of applying the emitted neutrons to a human patient. (Item 40) The emitted neutrons react with p+ 7 Li→n+ 7The method according to item 33, which is produced by the lithium layer according to Be. (Item 41) The method of item 33, further comprising the step of performing (a) and (b) as part of a boron neutron capture therapy (BNCT) procedure. (Item 42) The method according to item 33, wherein the charged particle radiation is in the form of a beam, and the target is exposed to the charged particle radiation in steps (a) and (b) while the beam is moved across the surface of the target in a direction transverse to the direction of propagation of the beam. (Item 43) (b) The method of item 33, further comprising the step of exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced in quantity and size. (Item 44) (b) further, the target emits neutrons and the multiple blisters are only of size The method according to item 33, comprising the step of exposing the target to further charged particle radiation so that it is reduced. (Item 45) (b) The method of item 33, wherein the step of exposing the target to further charged particle radiation further includes exposing the target to further charged particle radiation such that a lithium compound layer is formed between the lithium layer and the metal substrate. (Item 46) The method according to item 45, wherein the metal substrate is copper and the lithium compound layer is a lithium copper compound. (Item 47) (b) The method of item 45, wherein the step of exposing the target to further charged particle radiation further includes exposing the target to further charged particle radiation such that a lithium compound layer is formed between the lithium layer and the metal substrate to a depth that reaches or is adjacent to the plurality of blisters. (Item 48) The lithium layer having a thickness in the range of 1 micron to 300 microns, according to the method of item 33. (Item 49) The charged particle radiation is the method described in item 33, having an energy in the range of 1.9 MeV to 3.0 MeV. (Item 50) It is a method, (a) A step of exposing a region of a metal structure to charged particle radiation such that multiple deformations are formed within the region of the metal structure, wherein the metal structure comprises a lithium layer, (b) Exposing the region of the metal structure to further charged particle radiation such that the plurality of deformations are reduced in quantity and / or size. Methods that include... (Item 51) The method according to item 50, wherein the charged particle radiation is a proton beam. (Item 52) (b) The method of item 50, wherein the step of exposing the region of the metallic structure to further charged particle radiation includes exposing the region to further charged particle radiation until the amount of deformation is reduced by an order of magnitude. (Item 53) The method according to item 50, wherein the charged particle radiation is in the form of a beam, and the region is exposed to the charged particle radiation in steps (a) and (b) while moving the beam across the surface of the region in a direction transverse to the direction of propagation of the beam. (Item 54) The method according to item 50, wherein the metal substrate is copper. (Item 55) The lithium layer is in contact with the copper substrate, as described in item 50. (Item 56) The method according to item 50, wherein the metal structure is part of a plasma fusion reactor, and the charged particle radiation is emitted from the fusion reaction. (Item 57) The lithium layer having a thickness in the range of 1 micron to 300 microns, according to the method of item 50. (Item 58) The aforementioned modification is a blister, as described in item 50. (Item 59) (b) The method of item 58, wherein the step of exposing the region of the metallic structure to further charged particle radiation further includes the step of exposing the region to further charged particle radiation such that convection and / or capillary forces reduce the plurality of deformations in amount and / or size. (Item 60) It is a method, (a) A step of exposing a region of a metal structure to charged particle radiation such that multiple deformations are formed within the region of the metal structure, wherein the metal structure comprises a lithium layer, (b) Exposing a region of the metal structure to further charged particle radiation such that a lithium compound layer is formed between the lithium layer and the metal substrate to a size sufficient to reduce the plurality of deformations in quantity and / or size. Methods that include... (Item 61) The method according to item 60, wherein the charged particle radiation is a proton beam. (Item 62) (b) The method of item 60, wherein the step of exposing the area to further charged particle radiation includes exposing the area to further charged particle radiation until the amount of blister is reduced by an order of magnitude. (Item 63) The method according to item 60, wherein the charged particle radiation is in the form of a beam, and the region is exposed to the charged particle radiation in steps (a) and (b) while moving the beam across the surface of the region in a direction transverse to the direction of propagation of the beam. (Item 64) The method according to item 60, wherein the metal substrate is copper and the lithium compound layer is a lithium copper compound. (Item 65) The lithium layer having a thickness in the range of 1 micron to 300 microns, according to the method of item 60. (Item 66) The aforementioned modification is a blister, as described in item 60. (Item 67) It is a method, (a) A step of exposing a region of a metal structure to charged particle radiation such that multiple deformations are formed within the region of the metal structure, wherein the metal structure comprises a lithium layer, (b) Exposing regions of the metallic structure to further charged particle radiation such that the metallic substrate transitions from a crystalline state to an amorphous state sufficient to reduce the plurality of deformations in quantity and / or size. Methods that include... (Item 68) The method according to item 67, wherein the charged particle radiation is a proton beam. (Item 69) (b) The method of item 67, wherein the step of exposing the area to further charged particle radiation includes exposing the area to further charged particle radiation until the amount of blister is reduced by an order of magnitude. (Item 70) The charged particle radiation is in the form of a beam, and the region moves the beam across the surface of the region in a direction that transverses the direction of beam propagation, step by step. The method according to item 67, wherein the person is exposed to the charged particle radiation in (a) and (b). (Item 71) The method according to item 67, wherein the metal substrate is copper and the lithium compound layer is a lithium copper compound. (Item 72) The lithium layer having a thickness in the range of 1 micron to 300 microns, according to the method of item 67. (Item 73) The aforementioned modification is a blister, as described in item 67. (Item 74) (b) The method of item 67, wherein the step of exposing the region to further charged particle radiation further includes exposing the region to further charged particle radiation such that a lithium compound layer is formed between the lithium layer and the metal substrate. (Item 75) The method according to item 74, wherein the metal substrate is copper and the lithium compound layer is a lithium copper compound. (Item 76) (b) The method of item 74, wherein the step of exposing the region to further charged particle radiation further includes exposing the target to further charged particle radiation such that a lithium compound layer is formed between the lithium layer and the metal substrate to a depth that reaches or is adjacent to the plurality of deformations. (Item 77) (b) The method of item 67, wherein the step of exposing the region of the metallic structure to further charged particle radiation further includes the step of exposing the region to further charged particle radiation such that convection and / or capillary forces reduce the plurality of deformations in amount and / or size. (Item 78) It is a metallic body, A metal substrate and A layer containing lithium bonded to the aforementioned metal substrate Equipped with, The aforementioned metal body has at least 6.3 ± 0.6 × 10 20 protons per square centimeter (p / cm) -2 A metallic body exposed to the charged particle fluence of ) (Item 79) The metal body according to item 78, wherein the metal body exhibits a second resistance to blister formation that exceeds a first resistance to blister formation exhibited prior to the exposure. (Item 80) The aforementioned metal substrate is a metal body as described in item 78, containing copper. (Item 81) The metal body according to item 78, further comprising a lithium compound layer between the lithium-containing layer and the metal substrate. (Item 82) The lithium-containing layer is a metallic body according to item 81, comprising at least 90% lithium-7 isotopes. (Item 83) The lithium-containing layer is a metallic body according to item 81, comprising at least 98% lithium-7 isotopes. (Item 84) The first portion of the metal substrate is in an amorphous state, as described in item 78. (Item 85) The metal body according to item 84, wherein the second portion of the metal substrate is in a crystalline state, and the first portion is relatively closer to the lithium-containing layer than the second portion. (Item 86) A metallic body as described in item 78, configured for use in a plasma fusion reactor. (Item 87) A metallic body as described in item 78, configured for use as a neutron generating target. (Item 88) It is a metallic body, A metal substrate and The lithium-containing layer on the metal substrate and Equipped with, The metal body is a metal body in which one or more blisters are first formed in the metal body by charged particle radiation, and then the one or more blisters are exposed to the charged particle radiation so that they are reduced in size by the charged particle radiation. (Item 89) The metal body according to item 88, wherein the metal body exhibits a second resistance to blister formation that exceeds a first resistance to blister formation exhibited prior to the exposure. (Item 90) The aforementioned metal substrate is a metal body as described in item 88, containing copper. (Item 91) The metal body according to item 88, further comprising a lithium compound layer between the lithium-containing layer and the metal substrate. (Item 92) The lithium-containing layer is a metallic body according to item 91, comprising at least 90% lithium-7 isotopes. (Item 93) The lithium-containing layer is a metallic body according to item 91, comprising at least 98% lithium-7 isotopes. (Item 94) The first portion of the metal substrate is in an amorphous state, as described in item 88. (Item 95) The metal body according to item 94, wherein the second portion of the metal substrate is in a crystalline state, and the first portion is relatively closer to the lithium-containing layer than the second portion. (Item 96) A metallic body as described in item 88, configured for use in a plasma fusion reactor or as a neutron generation target. (Item 97) A target for use in boron neutron capture therapy (BNCT), Copper substrate and The lithium-containing layer on the copper substrate and Equipped with, The target is a target in which one or more blisters are first formed in the target by charged particle radiation, and then the one or more blisters are exposed to the charged particle radiation so that they are reduced in size by the charged particle radiation. (Item 98) The target according to item 97, wherein the target exhibits a second resistance to blister formation that exceeds a first resistance to blister formation exhibited prior to the exposure. (Item 99) The lithium is in solid form, as described in item 97. (Item 100) The lithium is in liquid form, as described in item 97. (Item 101) The aforementioned target is per square centimeter (cm -2 ) at least 0.5 × 10 19 The target according to item 97, configured to generate neutrons without substantial blister formation in the copper substrate when exposed to proton radiation having an average energy of 1.9 to 3.0 megaelectron volts (MeV) and a current in the range of 1 to 20 milliamperes (mA) until a proton fluence occurs. (Item 102) Reaction p+ 7 Li→n+ 7A target as described in item 101, configured to generate neutrons according to Be. (Item 103) A target for use in boron neutron capture therapy (BNCT), A first layer containing lithium, Copper substrate and A second layer containing a lithium copper compound is located between the first layer and the copper substrate. Equipped with, The aforementioned target is configured to generate neutrons when exposed to proton radiation. (Item 104) The target according to item 103, wherein the target is configured to generate neutrons when exposed to proton radiation without substantial blister formation in the copper substrate. (Item 105) The target according to item 103, wherein the target is configured to generate neutrons without substantial blister formation in the copper substrate when exposed to proton radiation having an average energy of 1.9 MeV to 3.0 MeV and a current in the range of 1 to 20 mA. (Item 106) Reaction p+ 7 Li→n+ 7 A target as described in item 103, configured to generate neutrons according to Be. (Item 107) The lithium layer is the target according to item 103, having a thickness in the range of 1 to 300 microns. (Item 108) A target for use in boron neutron capture therapy (BNCT), A first layer containing lithium, A copper substrate having a first portion in an amorphous state and Equipped with, The aforementioned target is configured to generate neutrons when exposed to proton radiation. (Item 109) The target according to item 108, wherein the target is configured to generate neutrons when exposed to proton radiation without substantial blister formation in the copper substrate. (Item 110) The target according to item 108, wherein the target is configured to generate neutrons without substantial blister formation in the copper substrate when exposed to proton radiation having an average energy of 1.9 MeV to 3.0 MeV and a current in the range of 1 to 20 mA. (Item 111) Reaction p+ 7 Li→n+ 7 A target as described in item 108, configured to generate neutrons according to Be. (Item 112) The first layer is a target as described in item 108, having a thickness in the range of 1 to 300 microns. (Item 113) The target according to item 108, wherein the second portion of the copper substrate is in a crystalline state, and the first portion is relatively closer to the first layer containing lithium than the second portion. (Item 114) The target according to item 108, further comprising a lithium copper compound layer between the first layer and the copper substrate. [Brief explanation of the drawing]

[0009] Details of the subject matter described herein, both in terms of its structure and operation, can be made clear by a close examination of the accompanying diagrams, where similar reference numbers refer to similar parts. Components in the diagrams are not necessarily to scale, but rather the emphasis is on illustrating the principles of the subject matter. Furthermore, all diagrams are intended to convey concepts, and relative sizes, shapes, and other detailed attributes may be illustrated graphically rather than literally or precisely.

[0010] [Figure 1A] Figures 1A, 1B, 1C, and 1D are perspective views illustrating exemplary embodiments of a metal body. [Figure 1B]Figures 1A, 1B, 1C, and 1D are perspective views illustrating exemplary embodiments of a metal body. [Figure 1C] Figures 1A, 1B, 1C, and 1D are perspective views illustrating exemplary embodiments of a metal body. [Figure 1D] Figures 1A, 1B, 1C, and 1D are perspective views illustrating exemplary embodiments of a metal body.

[0011] [Figure 1E] Figure 1E is a cross-sectional view illustrating an exemplary embodiment of a metal body, obtained along the cross-section of line 1E-1E in Figure 1D.

[0012] [Figure 2A] Figure 2A is a perspective view depicting an exemplary embodiment of a metal body during exposure to charged particle radiation in a first time period.

[0013] [Figure 2B] Figure 2B is a cross-sectional view depicting an exemplary embodiment, obtained by crossing the line 2B-2B in Figure 2A.

[0014] [Figure 2C] Figure 2C is a perspective view depicting an exemplary embodiment of a metal body during exposure to charged particle radiation at a second time point.

[0015] [Figure 2D] Figure 2D is a cross-sectional view depicting an exemplary embodiment, obtained by crossing line 2D-2D in Figure 2C.

[0016] [Figure 2E] Figure 2E is a perspective view depicting an exemplary embodiment of a metal body during exposure to charged particle radiation in a third time period.

[0017] [Figure 2F] Figure 2F is a cross-sectional view depicting an exemplary embodiment, obtained by crossing the line 2F-2F in Figure 2E.

[0018] [Figure 2G] Figures 2G and 2H are images depicting examples of blister formation on a crude copper surface before and after ion beam cutting, respectively. [Figure 2H] Figures 2G and 2H are images depicting examples of blister formation on a crude copper surface before and after ion beam cutting, respectively.

[0019] [Figure 3] Figure 3 is a flowchart illustrating an exemplary embodiment of a method for reducing blistering in a metal body.

[0020] [Figure 4A] Figure 4A is a perspective view depicting an exemplary embodiment of a metal body during exposure to charged particle radiation in a first time period.

[0021] [Figure 4B] Figure 4B is a cross-sectional view depicting an exemplary embodiment, obtained by crossing the line 4B-4B in Figure 4A.

[0022] [Figure 4C] Figure 4C is a perspective view depicting an exemplary embodiment of a metal body during exposure to charged particle radiation at a second time point.

[0023] [Figure 4D] Figure 4D is a cross-sectional view depicting an exemplary embodiment, obtained by crossing the line 4D-4D in Figure 4C.

[0024] [Figure 4E] Figure 4E is a cross-sectional view illustrating an exemplary embodiment with a partially formed compound layer.

[0025] [Figure 4F] Figure 4F is a perspective view depicting an exemplary embodiment of a metal body during exposure to charged particle radiation in a third time period.

[0026] [Figure 4G] Figure 4G is a cross-sectional view depicting an exemplary embodiment, obtained by crossing the line 4G-4G in Figure 4F.

[0027] [Figure 5] Figure 5 is a flowchart illustrating an exemplary embodiment of a method for reducing blistering in a metal body.

[0028] [Figure 6A] Figure 6A is a cross-sectional view illustrating an exemplary embodiment with partially formed amorphous regions and blisters.

[0029] [Figure 6B] Figure 6B is a cross-sectional view illustrating an exemplary embodiment of a metallic body with substantially formed amorphous regions and little to no blistering.

[0030] [Figure 7] Figure 7 is a flowchart illustrating an exemplary embodiment of a method for reducing blistering in a metal body.

[0031] [Figure 8A] Figure 8A is a schematic diagram illustrating an exemplary embodiment of an accelerator-based neutron beam system.

[0032] [Figure 8B] Figure 8B is a perspective view depicting an exemplary embodiment of a target configured to generate neutrons.

[0033] [Figure 8C] Figure 8C is a cross-sectional view of an embodiment obtained along the line 8C-8C in Figure 8B.

[0034] [Figure 8D] Figure 8D is another cross-sectional view of the embodiment having a lithium compound layer.

[0035] [Figure 8E] Figure 8E is another cross-sectional view of the embodiment, which has an amorphous region.

[0036] [Figure 8F] Figures 8F and 8G are front views of exemplary embodiments of a target, showing a stepped pattern and a helical pattern of beam movement, respectively. [Figure 8G] Figures 8F and 8G are front views of exemplary embodiments of a target, showing a stepped pattern and a helical pattern of beam movement, respectively.

[0037] [Figure 9A] Figures 9A, 9B, and 9C are flowcharts illustrating exemplary embodiments of a method for generating a neutron beam using a target with deformation-preventing benefits. [Figure 9B] Figures 9A, 9B, and 9C are flowcharts illustrating exemplary embodiments of a method for generating a neutron beam using a target with deformation-preventing benefits. [Figure 9C] Figures 9A, 9B, and 9C are flowcharts illustrating exemplary embodiments of a method for generating a neutron beam using a target with deformation-preventing benefits.

[0038] [Figure 10A] Figures 10A, 10B, and 10C are graphs illustrating the data collected during the experimental verification of the embodiments described herein. [Figure 10B] Figures 10A, 10B, and 10C are graphs illustrating the data collected during the experimental verification of the embodiments described herein. [Figure 10C] Figures 10A, 10B, and 10C are graphs illustrating the data collected during the experimental verification of the embodiments described herein.

[0039] [Figure 11A]Figures 11A, 11B, and 11C are images of the target region after exposure to the proton beam. [Figure 11B] Figures 11A, 11B, and 11C are images of the target region after exposure to the proton beam. [Figure 11C] Figures 11A, 11B, and 11C are images of the target region after exposure to the proton beam. [Modes for carrying out the invention]

[0040] Detailed explanation Before the subject matter is described in detail, it should be understood that this disclosure is not limited to the specific embodiments described and is therefore naturally subject to change. Furthermore, it should be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this disclosure, as it will be limited only by the appended claims.

[0041] The metal bodies that are the subject of the embodiments disclosed herein can be used in any of a wide range of applications (e.g., industrial, commercial, research, or other) and therefore can have any of a wide range of shapes, sizes, or configurations suitable for the needs of those applications. The metal bodies disclosed herein comprise at least a lithium layer and a metal The material includes a substrate. The metal substrate may consist primarily of one metallic element (e.g., a copper substrate with high purity), an alloy of two or more metallic elements, a compound of one or more metallic elements and one or more nonmetallic elements, or the like. Examples of metals for the substrate 104 include, but are not limited to, copper, aluminum, molybdenum, iron, silver, palladium, tantalum, carbon (e.g., graphite and diamond phases), tungsten, platinum, or gold. The lithium layer may similarly consist primarily of lithium, may be a lithium alloy or compound, or the like. The lithium layer may be in solid or liquid form. In the embodiments described herein, the lithium layer may consist of one or more lithium isotopes. For example, in embodiments described herein, the lithium layer may consist of at least 90% lithium-7 (7Li), at least 92% lithium-7, at least 95% lithium-7, at least 98% lithium-7, at least 99% lithium-7, at least 99.9% lithium-7, and equivalents. The remainder may be lithium-6 isotopes (6Li), other lithium isotopes, impurities, or other elements (for example, as in lithium compounds).

[0042] Figures 1A-1C are perspective views depicting exemplary embodiments of a metal body 102 having a lithium layer 103 and a metal substrate 104. The lithium layer 103 is shown as having an exposed surface (e.g., at the top of these figures), but the lithium layer 103 can also be embedded within the metal body 102 such that it does not form the outermost surface of the body 102. Similarly, the substrate 104 is shown as a bulk substrate with an exposed surface (e.g., at the bottom), but the substrate 104 can also be embedded within the body 102 such that it does not form the outermost surface (e.g., by inclusion of other structures or materials within the body 102).

[0043] In Figure 1A, the metal body 102 has a planar or flat form. In Figure 1B, the metal body 102 has a concave form exhibiting curvature in the YZ plane, and in Figure 1C, the metal body 102 has a convex form exhibiting curvature in the YZ plane. The concave and convex forms are represented from the reader's perspective. Figures 1A-1C depict several basic embodiments of the shape and surface contours that characterize the metal body 102. The metal body 102 may have more complex shapes and surface contours, including combinations of two or more of the shapes and surface contours depicted in Figures 1A-1C, or different and / or more complex ones. The body 102 shown in Figures 1A-1C may represent the entire physical extent of the body 102, or it may represent a larger part or segment of the metal body. The list of exemplary three-dimensional shapes relating to the body 102 includes, but is not limited to, plates or platings, disks, pillars, cubes or parts thereof, rectangular prisms or parts thereof, cylinders or parts thereof, prisms or parts thereof, cones or parts thereof, pyramids or parts thereof, spheres or parts thereof, rings or parts thereof, hollow chambers or parts thereof, any combination of two or more of the above, and others.

[0044] Figures 2A-2F depict exemplary embodiments of a metal body 102 having a lithium layer 103 on or adjacent to a metal substrate 104 during various stages of exposure to charged particle radiation. The body 102 is depicted here as planar (flat), but the mechanisms described in relation to these figures are equally applicable to all shape and size configurations of the body 102 discussed or included herein.

[0045] Figure 2A is a perspective view depicting a metallic body 102 with a region 201 of surface 204 during exposure to charged particle radiation in a first time period. Figure 2B is a cross-sectional view depicting the body 102, obtained by crossing line 2B-2B in Figure 2A. The incident direction of the charged particle radiation is indicated in this embodiment by a vector 203 which is normal to surface 204. In this embodiment, the fluence (a bundle integrated over time, where the bundle is the area of ​​a unit area at a given moment) is The number of particles per region is constant across region 201 (for example, the entire surface region 201 is simultaneously exposed to a uniform distribution of charged particle radiation, or a beam of charged particle radiation having a smaller cross-sectional area than that of region 201 is moved across region 201 in a uniform manner as will be described herein). In the first time period shown in Figures 2A and 2B, no blistering occurs in the metal body 102.

[0046] Figure 2C is another perspective view depicting the body 102, and Figure 2D is a cross-sectional view depicting the body 102, obtained by crossing line 2D-2D in Figure 2C. Additional long-term exposure of region 201 to charged particle radiation resulted in the formation of deformation 208, which is a blister in this embodiment. The visual appearance and mechanism of blister formation 208 can vary. In this embodiment, the formation of gaseous pockets 209 within the substrate 104 deformed the surrounding material and appeared as a visible blister (e.g., deviation of surface contour, raised surface formation, protrusions, cracks, etc.) in region 201 of the surface 204.

[0047] The blistering threshold (e.g., the dose at which blistering begins) depends on various factors such as the type of metal substrate, the sample temperature during irradiation, the type of radiation (e.g., ions, protons), the energy of the radiation, and others. (Badrutdinov et al.) Previous studies, such as "In Situ Observations of Blistering of a Metal Irradiated with 2-MeV Protons" (Metals 2017, 7, 558), describe that the blistering threshold of copper surfaces depends on copper purity, with higher thresholds for purer copper. Batrutdinov states that for a proton energy of 2 megaelectron volts (MeV), the maximum threshold for copper is 3 × 10⁻¹⁶. 19 cm -2It is stated that the minimum value can be as low as 7 times. Furthermore, the size of the blister on the copper surface depends on the copper purity; the purer the copper, the larger the blister. Copper blister sizes resulting from 2 MeV proton radiation can range from 40 ± 20 microns to 160 ± 50 microns. Figures 2G and 2H are images depicting examples of blisters on the surface of 99.99996% crude copper before and after being cut by an ion beam. A gaseous pocket is visible inside the cut blister in Figure 2H.

[0048] Figure 2E is another perspective view depicting the metal body 102, and Figure 2F is a cross-sectional view depicting the body 102 obtained by crossing the line 2F-2F in Figure 2E. Further exposure of region 201 to charged particle radiation after the formation of the blister 208 reduced or diminished the size of the blister 208. Figure 2F shows that the volume of the gaseous pocket 209 was reduced compared to Figure 2D, which in turn reduced the height of the blister 208 (Figure 2F compared to Figure 2D) and the surface area of ​​the raised portion of the blister 208 (Figure 2E compared to Figure 2C).

[0049] The application of charged particle radiation in this embodiment, at least up to the point where blister reduction begins, results in a metal body 102 with enhanced resistance to blister formation. As radiation is applied beyond this point, the blisters 208 continue to decrease, and the resistance to blister formation is further increased. Thus, the metal body 102 exposed to the process described with respect to Figures 2A-2F undergoes a form of material modification that enhances its resistance to further blister formation.

[0050] Figure 3 is a flowchart illustrating an exemplary embodiment of Method 300 by the process described with respect to Figures 2A-2F. In step 302, charged particle radiation is applied to a region of the metal body 102 (for example, having lithium as described with respect to Figures 2A-2B). In step 304, additional charged particle radiation is applied so that one or more blisters (for example, as described with respect to Figures 2C-2D) are formed and grow in size within the region. In step 306, further Charged particle radiation is applied so that one or more blisters are reduced in size. Depending on the application, step 306 may continue until blister size reduction substantially stops, until some or all blisters are eliminated, or continuously after blister elimination. In some embodiments, the interval between steps 304 and 306 may include a stage where blister formation in the region stops or substantially stops (or blister size growth in the region stops or substantially stops), but blister size reduction has not yet occurred. Charged particle radiation is further applied.

[0051] The lithium layer 103 can be in direct contact with the metal substrate 104, as depicted in Figures 1A-1C. In some embodiments described herein, a compound can be formed or located between the lithium layer 103 and the metal substrate 104. Figure 1D is a perspective view depicting a planar metal body 102 with a lithium layer 103, a metal substrate 104, and a lithium-metal compound layer 105 located between 103 and 104. The compound may include lithium (from layer 103) and one or more metals of the metal substrate 104. For example, when the substrate 104 is copper, layer 104 may be a lithium-copper compound (e.g., LiCu). The formation of this compound layer 104 may be induced by the interaction between the body 102 and the charged particle radiation itself, by the heat generated from the charged particle radiation (or by radiation-induced nuclear reactions), or by other mechanisms. In embodiments where the metal substrate 104 itself has a layered structure, the lithium compound layer 105 can be formed between the lithium layer 103 and the nearest adjacent layer of the metal substrate 104.

[0052] Figure 1E is a cross-sectional view depicting this exemplary embodiment, obtained along the cross-section of line 1E-1E in Figure 1D. As labeled in Figure 1E, the lithium layer 103 has a thickness of 110, the lithium compound layer 105 has a thickness of 112, and the substrate 104 has a thickness of 114. The relative thicknesses here are merely illustrative. The substrate 104 will generally be the thickest layer in most embodiments, but such a thing is not required. The transition 120 between the lithium layer 103 and the lithium compound layer 105 can be immediate or gradual, as can the transition 130 between the lithium compound layer 105 and the substrate 104.

[0053] Figures 4A–4G depict another exemplary embodiment of the metal body 102 at various stages of charged particle radiation exposure. As in the embodiment of Figure 2A–2F, the body 102 is depicted here as planar (flat), but the subject matter described in relation to these figures is equally applicable to all shape and size configurations of the body 102 discussed or included herein. The lithium compound layer 105 is formed during the sequence of operations depicted in Figure 4A–4G. In these embodiments (as well as those in Figures 5 and 9B, etc.), the mechanism by which blister size reduction and elimination occurs is the formation of the lithium compound layer; however, the embodiments described herein are not limited to such examples (as demonstrated by the embodiments in Figures 3, 7, 9A, and 9C, for example), and the scope of the subject matter described herein also covers other mechanisms.

[0054] Figure 4A is a perspective view depicting a metal body 102 in which a region 201 of the surface 204 is exposed to charged particle radiation in a first time period. Figure 4B is a cross-sectional view depicting the body 102 obtained by crossing the line 4B-4B in Figure 4A. Figures 4A and 4B are analogous to Figures 2A and 2B, respectively. The direction of incidence of the charged particle radiation is indicated in this embodiment by a vector 203 which is normal to the surface 204. In this embodiment, the fluence is constant across region 201 (for example, the entire surface region 201 is simultaneously exposed to a uniform distribution of charged particle radiation, or a beam of charged particle radiation having a smaller cross-sectional area than that of region 201 is moved across region 201 in a uniform manner as will be described herein). In this first time period in Figures 4A and 4B, no blistering occurs in the metal body 102.

[0055] Figure 4C is another perspective view depicting the metal body 102, and Figure 4D is a cross-sectional view depicting the metal body 102 obtained by crossing the line 4D-4D in Figure 4C. Additional long-term exposure of region 201 to charged particle radiation resulted in the formation of a blister 208. The visual appearance and mechanism of the blister 208 formation can vary. In this embodiment, the formation of gaseous pockets 209 within the substrate 104 deformed the surrounding material and appeared as visible deformation (e.g., deviation of the surface contour, formation of raised surfaces, protrusions, cracks, etc.) in region 201 of the surface 204. At the stages depicted in Figures 4A-4D, no lithium compound layer has yet formed, or any lithium compound layer that has formed is either not thick enough to prevent blister formation, or is not thick enough to prevent blister formation, as depicted in Figure 4E.

[0056] Figure 4F is another perspective view depicting the metal body 102, and Figure 4G is a cross-sectional view depicting the body 102 obtained across the line 4G-4G in Figure 4F. Here, further exposure of region 201 to charged particle radiation after the formation of the blister 208 resulted in the formation of a lithium compound layer 105 of sufficient size (e.g., depth 402 in Figure 4G) within region 201 to reduce or decrease the size of the blister 208. In some implementations, it is desirable to form the compound layer 105 such that it is of sufficient size and exists uniformly across the relevant portion of the body 102 (e.g., across the entire region 201). Figure 4G shows that in this embodiment, the depth of the lithium compound layer 105 reaches or is close to the gaseous pocket 209, allowing the gas in the pocket 209 to diffuse out of the body 102 through layers 105 and 103. The lithium-copper compound layer 105 has increased diffusivity to hydrogen gas compared to copper alone, thus allowing hydrogen gas within the volume of pocket 209 to diffuse outward and escape. As a result, the size of pocket 209 is reduced compared to Figure 4D, which in turn reduces the height of the raised portion of blister 208 (Figure 4G compared to Figure 4D) and the surface area of ​​the raised portion of blister 208 (Figure 4F compared to Figure 4C).

[0057] Since the visual appearance and mechanism of blister formation 208 can vary, the manner in which blisters are reduced can also vary. Embodiments of blister reduction in size include reduction in the exposed surface area of ​​the blister 208 on surface 204, reduction in the height of the blister 208 (such as measured relative to the height of an adjacent non-blister surface or the height of a surface preceding blistering), reduction in the height or volume of the gaseous pocket 209, reduction in the size (width or length) of a crack within surface 204, reduction in the height of a flake of material deflected from surface 204, and others. Blisters 208 in the form of raised protrusions (e.g., Figures 2C-2D and 4C-4D) can also be substantially eliminated such that blister reduction results in a reduction in the overall count of blisters 208 in a particular area of ​​body 102.

[0058] The application of charged particle radiation in the embodiments of Figures 4A-4G up to the point where a lithium compound layer 105 of sufficient size to enable blister reduction is generated results in a metal body 102 with enhanced resistance to blister formation. As radiation is applied beyond this point, the blisters 208 continue to decrease, and the resistance to blister formation is further increased. Thus, a metal body 102 exposed to the process described with respect to Figures 4A-4G undergoes a form of material modification that enhances its resistance to blister formation.

[0059] Blisters generally form in the bulk of the material where the incident particle stops. For particles of the same energy, the range of propagation will generally follow a probability distribution (e.g., Gaussian) and will increase with energy. The projected range depends mainly on the material as well as the energy and type of the incident particle. For example, the range of propagation of a 2 MeV energy particle incident on different materials will vary. The protons present will have the approximate projected range shown in Table 1. [Table 1]

[0060] Adding a lithium layer 103 above the non-lithium bulk substrate would slightly decelerate the incident particles and reduce the stopping distance shown in Table 1. Table 1 is useful in demonstrating the relative thickness differences that occur in the bulk material when blisters are formed and suggests the degree of relative thickness that the compound layer 105 should be in order to reach the particle projection range.

[0061] Figure 5 is a flowchart illustrating an exemplary embodiment of Method 500 by the process described with respect to Figures 4A–4G. In step 502, charged particle radiation is applied to a region of the metal body 102 (for example, as described with respect to Figures 4A–4B). In step 504, additional charged particle radiation is applied (for example, as described with respect to Figures 4C–4D) to form and grow in size within the region. In step 506, further charged particle radiation is applied to form a lithium compound layer having sufficient size (e.g., thickness) to reach or be adjacent to (nearly reach) one or more blisters. Reaching or nearly reaching one or more blisters can allow one or more blisters to be reduced in size or eliminated using further radiation. Step 506 may continue, depending on the application, until blister size reduction substantially ceases, until all blisters are eliminated, until a lithium compound layer of the desired size or thickness is formed, or even longer. In some embodiments, the interval between steps 504 and 506 may include a stage where blister formation in the region has stopped or substantially stopped (or blister size growth in the region has stopped or substantially stopped), but blister size reduction has not yet occurred.

[0062] In some embodiments, charged particle radiation can induce a partial or complete transition of the substrate material from a crystalline (including crystalline and polycrystalline) state to an amorphous state by disrupting crystalline bonds. Figures 6A–6B are cross-sectional views similar to those in Figures 4E–4G, depicting the formation of amorphous bulk material. In these embodiments, the transition to amorphous material occurs during and after the formation of lithium compounds, but the formation of amorphous material occurs independently of compound formation. This can occur. In Figure 6A, charged particle radiation 203 results in the formation of a blister 208 with a gaseous pocket 209. The formation of the lithium compound layer occurs in the direction of arrow 602. The transition of the substrate material (e.g., copper) from a crystalline state to an amorphous state can occur partially, as shown by pattern 604. Continued exposure to radiation 203 causes the compound layer 105 to thicken away from the surface 204, resulting in an additional material transition to the amorphous state 604 in both the compound layer 105 and the substrate region 104, particularly in the blister shell region between the gaseous pocket 209 and the lithium layer 103. The transition to the amorphous state in these regions can be complete or partial (e.g., greater than 50%, greater than 75%, or greater than 90%). In some embodiments, this transition to the amorphous state can be one or the primary cause of blister reduction or elimination. The amorphous transition can work in conjunction with the formation of the compound layer 105 to cause blister reduction. Other mechanisms can contribute in a similar manner.

[0063] Figure 7 is a flowchart illustrating an exemplary embodiment of Method 700 by the process described with respect to Figures 6A–6B. In step 702, charged particle radiation is applied to a region of the metal body 102 (for example, as in Figures 4A–4B). In step 704, additional charged particle radiation is applied so that one or more blisters are formed and grow in size (for example, as described with respect to Figure 6A), and the substrate region of the metal body 102 is partially transitioned from a crystalline state to an amorphous state. This may involve the growth of a lithium compound layer and a partial transition of that compound from a crystalline state to an amorphous state. In step 706, further charged particle radiation is applied so that the transition from crystalline to amorphous states continues to a sufficient extent (e.g., 50%, 75%, 90%, or more of the transition to an amorphous state) to reduce the blisters 208. This transition can occur throughout the entire metal body 102, but for the purpose of blister reduction, the transition occurs at least in the region of the substrate (and compound, if present) between the blister and the top surface 204 (the lithium layer does not need to transition). In some embodiments, blister reduction may also be conditional on the expansion of the compound layer to a depth that reaches or is adjacent to (nearly reaches) one or more blisters. Depending on the application, step 706 may continue until blister size reduction substantially stops, until all blisters are eliminated, until a lithium compound layer of the desired size or thickness is formed, or longer. In some embodiments, the interval between steps 704 and 706 may include a stage where blister formation in the region stops or substantially stops (or blister size growth in the region stops or substantially stops), but blister size reduction has not yet occurred.

[0064] Embodiments of the metal body 102 described herein can undergo method 300, 500, or 700 during the operation of a device in which the body 102 is a component or element, and thus can undergo blister resistance adjustment during the operation itself. Alternatively (or in addition), embodiments of the metal body 102 can undergo method 300, 500, or 700 prior to operation as a method of manufacture or adjustment, and the adjusted material can then be assembled or installed as part of a larger system or device, or otherwise, first be operated in a desired application with increased blister resistance.

[0065] In the embodiments described herein and other embodiments, charged particle radiation can be applied continuously or intermittently to achieve blister reduction and / or resistance. For example, during a radiation application procedure, radiation can be applied continuously or in a pulsed manner (e.g., intermittently at a constant or variable frequency) (e.g., by a beam or reaction). This radiation application procedure may be performed over a substantial time period (e.g., when the system is powered off or otherwise taken offline for system maintenance or other reasons). It can be stopped (for example, when it is stopped) and then restarted, and the benefits of blister prevention can still be achieved, even with this intermittent cycle of the entire system.

[0066] (With respect to Figure 2A-7 above and other embodiments thereafter) The metal body 102 operating in or tuned in the processes described herein can be used in a number of applications. For example, the metal body 102 can be used in plasma fusion devices such as plasma-facing walls for the confinement chamber of a fusion reactor. The metal body 102 can also be used in particle accelerators, ion implantation devices, satellites and spacecraft, devices for isotope production, devices for hazardous substance detection, devices for precious metal mineral assays, imaging devices, and others.

[0067] One notable exemplary application is boron neutron capture therapy (BNCT), in which the metal body 102 can be configured for use as a target device for generating neutrons in a neutron beam system. An example of the neutron beam system 800 is described in more detail with reference to Figure 8A of this specification.

[0068] BNCT is a form of radiotherapy for cancer treatment. In BNCT, the patient is administered a drug containing boron, which has the property of selectively absorbing boron by cancer cells in any tumor site within the patient's body. The patient is then exposed to neutron radiation, particularly epithermal neutrons with energies in the range of 1 kiloelectron volt (keV) to 10 keV, and in some cases as high as 30 keV. These epithermal neutrons interact with boron through nuclear reactions, which produce alpha particles with very short ranges, for example, about the thickness of a single cell. Thus, exposure of boron-containing cancer cells to epithermal neutrons generates alpha radiation at a dose sufficient to kill the tumor cells without serious side effects on surrounding tissues.

[0069] To generate a sufficient beam of epithermal neutrons, a charged particle beam such as a proton (or positive hydrogen ion (H+)) beam is used. 7 Li is targeted, followed by a nuclear reaction p+ 7 Li→n+ 7 Be generates a neutron beam. 7 Li is generally considered an optimal neutron-generating target material for two reasons. Firstly, it offers one of the highest proton-to-neutron conversion ratios. Secondly, p+ 7 Li is an endothermic reaction, requiring the proton energy to exceed a certain threshold of approximately 1.9 MeV for neutron generation to occur. Neutrons generated at or above this threshold (e.g., 1.9 MeV to approximately 3.0 MeV) generally have neutron energies below 1 MeV and can be relatively easily slowed down to the extrathermal range of approximately 1 keV to 30 keV.

[0070] Neutrons can be slowed using a decelerator. Deceleration via the decelerator nucleus occurs due to elastic and inelastic scattering, which has stochastic properties because neutron motion is similar to Brownian particle motion. As a result, the neutron energy spectrum becomes narrower as the primary neutron energy decreases. In this context, this is characterized by the rapid growth of the cross-section near the neutron generation threshold. 7 Li(p,n) 7 The Be reaction is considered ideal because the amount of neutrons produced in the soft (e.g., <1 keV) and hard (>30 keV) energy ranges can be minimized. Clinicians generally desire that the amount of soft and hard neutrons be minimized because they result in higher patient toxicity and more serious side effects. Therefore, 7 Neutron beam systems operating within this range, above the energy threshold of Li reactions, can be configured to strike an optimal balance between neutron yield and the quality of the resulting neutron energy spectrum.

[0071] Since the neutron generation reaction is endothermic, a significant amount of heat is generated. 7 Li targets (many) In the case of lithium targets (simply referred to as lithium targets), this needs to be taken into consideration. Previous solutions involved placing a lithium layer on a metal substrate with high thermal conductivity (e.g., copper) in combination with water cooling to maintain a sufficiently low temperature for the target or target assembly so that the lithium does not evaporate (e.g., does not form radioactive contamination within the beamline). However, these previous solutions are susceptible to blistering as a result of the application of high-energy proton beams, and much effort has been spent to prevent blister formation in lithium targets.

[0072] Blister prevention techniques often involve the placement of blistering prevention material between the lithium and the underlying copper substrate. Materials with high hydrogen diffusion coefficients (e.g., tantalum, niobium, vanadium, and palladium) are used; however, these materials tend to have much lower thermal conductivity than copper, which can make cooling the target more difficult.

[0073] Generally, lithium is characterized by high chemical activity, a low melting point (e.g., 182°C), and low thermal conductivity (e.g., 71 W / (m K) in the solid state and 43 W / (m K) in the liquid state), making the design of lithium neutron generation targets a challenging technical task. Other considerations should also be taken into account. For example, in addition to generating heat, neutron generation is accompanied by a gamma-ray flux. To significantly reduce the gamma-ray flux and temperature on the lithium surface, the lithium layer should be thin enough so that protons are slowed down to the neutron generation threshold within it. It is also desirable to use lithium of relatively high purity to maximize the neutron yield. For example, relatively pure lithium provides a neutron yield approximately 1.43 times higher than lithium hydride, approximately 2 times higher than lithium oxide, and approximately 3.3 times higher than lithium fluoride. To prevent lithium evaporation, which can contaminate beam systems and equipment with radioactive Be7 (trapped inside the lithium), the target should be intensively cooled. A thin underlayer substrate should be used to allow the neutron moderator of the beam shaping assembly to be positioned as close as possible to the lithium layer. In some cases, it is desirable that the target have an overall thickness less than the total projection range of protons. Furthermore, it is desirable that the substrate be resistant to radiation damage, easy to manufacture, and easy to remove from the system to facilitate disposal.

[0074] Figure 8A is a schematic diagram depicting an exemplary embodiment of an accelerator-based neutron beam system 800. While the configuration of the neutron beam system varies, in this embodiment, system 800 includes a low-energy beamline 820 that serves as an ion beam injector, a high-voltage (HV) tandem accelerator 840 coupled to the ion beam injector 820, and a high-energy beamline 850 extending from the tandem accelerator 840 to a lithium target assembly 801 that can house a lithium target 802 (see Figure 8B). The ion beam injector 820 may include an ion source 822, an ion source vacuum box 824 extending from the ion source 822, a pre-accelerator tube 826 coupled to the ion source vacuum box 824, and a pressure chamber (e.g., with an integrated Faraday cup) 828 coupled between the pre-accelerator tube 826 and the tandem accelerator 840. The ion source 822 serves as a source of charged particles (in exemplary embodiments, negative hydrogen ions), which can be accelerated, conditioned, and ultimately delivered to the lithium target 802 to generate neutrons.

[0075] Two types of negative ion sources 822, differing in their mechanisms of negative ion generation, are surface type and volume type. The surface type requires the presence of cesium (Cs) on a specific internal surface. A discussion of the surface type negative ion source is provided in the published PCT application WO2014039579A2 (which is incorporated herein by reference in its entirety for all purposes). The volume type requires the generation of negative ions within the volume of a high-current discharge plasma. It relies on ON formation. Both types of ion sources can deliver a sufficient negative ion current.

[0076] The ion source vacuum box 824, the pre-accelerator tube 826, and the pressurized chamber 828 are configured to transfer the ion beam from the ion source 822 to the input of the tandem accelerator 840. The low-energy beamline 820 may have one or more magnetic elements to focus and steer the beam and align the beam with the beamline axis and the receiving angle of the tandem accelerator 840.

[0077] The pre-accelerator tube 826 provides acceleration for the negative ion beam injected from the ion source 822. The pre-accelerator tube 826 plays a crucial role in beam focusing to achieve overall focusing to match the aperture area at the entrance of the high-voltage tandem accelerator 840.

[0078] A tandem accelerator 840, coupled to it and powered by a high-voltage power source 842, can generate a proton beam with an energy equal to twice the voltage applied to the accelerating electrodes located within the tandem accelerator 840. The energy level of the proton beam is achieved by accelerating a beam of negative hydrogen ions from the input of the tandem accelerator 840 to the innermost high-potential electrode, removing two electrons from each ion, and then accelerating the resulting protons (H+ ions) downstream by the same applied voltage.

[0079] The high-energy beamline 850 transports a proton beam from the output of the tandem accelerator 840 to a target 802 in a target assembly 801, which is located at the end of a beamline branch 870 that extends into a patient treatment room. In the exemplary embodiment shown in Figure 8A, the high-energy beamline 850 includes three branches 870, 880, and 890 for extending into three different patient treatment rooms. The high-energy beamline 850 may include a pump chamber 851, quadrupole magnets 852 and 872 for preventing beam out-focusing, dipole or bending magnets 856 and 858 for steering the beam into the treatment room, a beam corrector 853, diagnostics such as current monitors 854 and 876, a high-speed beam position monitor 855 section, and a scanning magnet 874.

[0080] The design of the high-energy beamline 850 depends on the configuration of the treatment facility. The configuration in Figure 8A relates to a two-story treatment facility. One of the treatment rooms, closer to the target assembly 801, is located on the lower floor. The beam is delivered to the target assembly 801 using a bending magnet 856. A quadrupole magnet 872 then focuses the beam to a certain size on the target 802. The beam can be moved across the surface of the target 802 by a magnet 874 (e.g., raster, scanning, or oscillation). Beam movement can help achieve a smooth and uniform time-averaged distribution of the proton beam on the lithium target 802, prevent overheating, and make neutron generation more uniform within the lithium layer of the target 802.

[0081] After traversing the scanning magnet 874, the beam is delivered into the current monitor 876, which measures the beam current and can act as a safety interlock. The target assembly 801 can be physically separated from the high-energy beamline volume using a gate valve 877. The function of the gate valve is to separate the beamline vacuum volume from the target during target replacement / loading. The horizontal orientation of the beamline (for a second and possibly third treatment room away from branches 880 and 890) is also shown (partially) in Figure 8A. In this case, the beam is not bent 90 degrees by the bending magnet 856, but rather travels in a straight line to the right, and then passes through the quadrupole magnet 852, which is located within the horizontal beamline. The beam can then be bent to the required angle, depending on the room configuration, by another bending magnet 858. Otherwise, the bending magnet 858 is replaced with a Y-shaped magnet to split the beamline in two directions for two different treatment rooms located on the same floor. The beam impact on target 802 generates a neutron beam, which can then be shaped and modified by a neutron beam shaping assembly (not shown), which can then direct the neutron beam directly to the patient.

[0082] Figure 9A is a flowchart depicting an exemplary embodiment of a method 900 for generating a neutron beam, similar to the process described with respect to Figure 3. In step 902, a proton beam is applied to a region of target 802 (for example, as described with respect to Figures 2A-2B). The proton beam preferably has an energy in the range of 1.9 MeV to 3.0 MeV, but is not limited to such an energy. The proton beam can be applied in a continuous or pulsed manner, can be held in a static position, or can be moved across the surface of target 802 in any desired pattern (see Figures 8E and 8F, showing stepwise and helical patterns, respectively). In step 904, the proton beam is applied so that one or more blisters are formed and grow in size within the region (for example, as described with respect to Figures 2C-2D). This can be done without a significant decrease in neutron yield, as will be described with respect to Figures 10B-10C. In step 906, the proton beam is further applied so that one or more blisters are reduced in size. Step 906 may be continued until blister size reduction substantially stops, until all blisters are eliminated, or thereafter to continue neutron production for BNCT. Again, proton irradiation may be continued without a significant decrease in neutron yield, for example, as long as the lithium layer does not become excessively thin. In some embodiments, the interval between steps 904 and 906 may include a stage where blister formation in a region stops or substantially stops (or blister size growth in a region stops or substantially stops), but blister size reduction has not yet occurred.

[0083] Figure 9B is a flowchart depicting an exemplary embodiment of method 950 for generating a neutron beam, similar to the process described with respect to Figure 5. In step 952, a proton beam is applied to a region of target 802 (for example, as described with respect to Figures 4A-4B). As in the embodiments described above, the proton beam preferably has an energy in the range of 1.9 MeV to 3.0 MeV, but is not limited to such an energy. The proton beam can again be applied in a continuous or pulsed manner, held in a static position, or moved across the surface of target 802 in any desired pattern. In step 954, the proton beam is applied so that one or more blisters are formed and grow in size within the region (for example, as described with respect to Figures 4C-4D). This can be done without a significant decrease in neutron yield, as will be described with respect to Figures 10B-10C. In step 956, the proton beam is further applied so that the lithium compound layer is formed to a size (e.g., thickness) sufficient to reach or be adjacent to (nearly reach) one or more blisters, and so that one or more blisters can be reduced in size using further radiation. Step 956 may be continued until blister size reduction substantially stops, until all blisters are eliminated, until a lithium compound layer of the desired size or thickness is formed, or thereafter to continue neutron generation for BNCT. Again, proton irradiation may be continued without a significant decrease in neutron yield, for example, as long as the lithium layer does not become excessively thin through the formation of the compound layer. In some embodiments, the interval between steps 954 and 956 may include a stage where blister formation in a region stops or substantially stops (or blister size growth in a region stops or substantially stops), but blister size reduction has not yet occurred.

[0084] Figure 9C is a flowchart depicting an exemplary embodiment of method 980 for generating a neutron beam, similar to the process described with respect to Figure 7. In step 982, a proton beam is applied to a region of target 802. The proton beam preferably has an energy in the range of 1.9 MeV to 3.0 MeV, but is not limited to such an energy. The proton beam can again be applied in a continuous or pulsed manner, held in a static position, or moved across the surface of target 802 in any desired pattern. In step 984, the proton beam is applied so that one or more blisters (as described, for example, with respect to Figure 6A) are formed and grow in size, and the substrate region of target 802 partially transitions from a crystalline state to an amorphous state. This may involve the growth of a lithium compound layer and the partial transition of that compound from a crystalline state to an amorphous state. This can be done without a significant decrease in neutron yield, as will be described with respect to Figures 10B-10C. In step 986, further charged particle radiation is applied so as to continue until the transition to the amorphous state is sufficient to allow blistering to be reduced (e.g., 50%, 75%, 90%, or more of the transition to the amorphous state). This transition may occur throughout the entire target 802, but for the purpose of blister reduction, the transition occurs at least in the region of the target 802 between the blister and the top surface 204 (the lithium layer does not need to transition). Step 986 may continue until blister size reduction substantially stops, until all blisters are eliminated, until a lithium compound layer of the desired size or thickness is formed, or thereafter to continue neutron generation for BNCT. In some embodiments, blister reduction may also be conditional on the expansion of the compound layer to a depth where one or more blisters are reached or adjacent to (nearly reached). Step 986 may be continued, depending on the application, until blister size reduction substantially ceases, until all blisters are eliminated, until a lithium compound layer of the desired size or thickness is formed, or longer.Again, proton irradiation can be continued without a significant decrease in neutron yield, for example, as long as the lithium layer does not become excessively thin through the formation of a compound layer. In some embodiments, the interval between steps 984 and 986 may include a stage in which blister formation in the region stops or substantially stops (or blister size growth in the region stops or substantially stops), but blister size reduction has not yet occurred.

[0085] Embodiments of target 802 described herein may undergo methods 900, 950, or 980 during the operation of the neutron beam system 800. This system operation may be for the purpose of tuning target 802 to enhance its blister resistance when used on a patient. Alternatively, this system operation may be such that, while the patient is being treated, blisters are formed during one or more procedures that directly apply neutrons to the patient for therapeutic purposes and are reduced in size. Implementation of methods 900, 950, or 980 can also be carried out by the operation of system 800 during a combination of non-patient and patient use. In another embodiment, methods 900, 950, and / or 980 may be implemented during the fabrication of target 802 (e.g., prior to the distribution of target 802 to a BNCT patient center) using radiation generated by a charged particle radiation system other than one designed for use on human patients.

[0086] Referring again to Figure 8B, this figure is a perspective view depicting an exemplary embodiment of target 802 prior to exposure to sufficient particle radiation to induce blistering. In this embodiment, target 802 is disk-shaped and is analogous to metal body 102 in that it comprises a lithium layer 103 and a metal substrate 104. Although copper is shown to be particularly advantageous as a material for substrate 104, embodiments herein are not limited to such materials. Figure 8C is a cross-sectional view of target 802 obtained along line 8C-8C in Figure 8B. Figure 8C depicts the presence of a cooling channel 804 on the back side of the substrate 104. The channel 804 can be used to circulate a coolant across the back side of the substrate 104 during the operation of the system 800 to dissipate the heat generated by the endothermic neutron generation reaction. Figure 8D is a cross-sectional view of the target 802 after exposure to sufficient particle radiation to form a lithium compound layer 105. In embodiments where the substrate 104 is copper, the lithium compound layer 105 is a lithium copper compound. Figure 8E is a cross-sectional view of the target 802 after exposure to sufficient particle radiation to form an amorphous region 604 within the substrate 104.

[0087] Figures 8F and 8G are front views of the target 802 showing a stepped pattern 860 and a helical pattern 862 of beam movement, respectively. The beam can be continuously moved back and forth along these patterns in both directions (one direction is shown in the figure). Depending on the beam spot size, the patterns may or may not result in a uniform fluence delivered across the entire surface of the target 802. The deformation-preventing benefits described herein can be realized with both uniform and non-uniform fluences across the surface of the target 802 depicted herein. In these embodiments, the lithium layer is present across the entire surface shown herein; however, in other embodiments of the target 802, the lithium layer may be limited only to the inner region of the surface shown herein.

[0088] The lithium layer 103 may be in either a solid or liquid form. If in a liquid form, the lithium layer 103 can be laid across the substrate 104 in solid form so that the solid substrate can be oriented at a desired angle (e.g., 0–90 degrees) with respect to the incident beam axis. The liquid lithium should be formed across the substrate in a manner that does not allow a significant amount of lithium to evaporate (and thereby potentially contaminate the system or equipment). The liquid lithium layer enables the utilization of substantially higher power densities of the proton beam, which in turn allows for the use of relatively smaller target diameters or widths.

[0089] The lithium layer 103 can preferably have a thickness sufficient to allow the growth of the lithium compound layer while maintaining a constant neutron yield, since the diffusion of lithium into the substrate will thin the lithium layer 103. Table 2 lists exemplary lithium properties for different proton energies in naturally abundant lithium (e.g., 7Li containing about 10% 6Li). The projected range in lithium is the range over which a proton ceases motion at each energy. The depth to threshold is the depth in lithium to which the proton reaches about 1.88 MeV, the threshold at which it stops producing neutrons. For pure 7Li, the depth to threshold is slightly higher (e.g., 17.7 microns for 2.00 MeV and 92.5 microns for 2.50 MeV). [Table 2]

[0090] The lithium layer used in a neutron generation target preferably has a thickness of at least the depth to the threshold, and therefore the desired thickness of the lithium layer depends on the expected energy of the incident proton. Generally, the lithium layer thickness for BNCT applications can be in the range of 1 to 300 microns to accommodate proton energies in the range of 1.88 to 3.0 MeV.

[0091] Figures 10A–10C are graphs illustrating data collected during the experimental verification of the embodiments described herein. These experimental data reflect results collected after exposing an embodiment of target 802 to proton radiation in the form of a beam generated by an embodiment of neutron beam system 800 similar to that described with respect to Figures 8A–8C. The target under study contained a substrate 104 of 99.996% fine-grained copper with a lithium layer 103 having a thickness of 84 μm (microns) evaporated onto the substrate 104. The target was irradiated with a proton beam having a diameter of approximately 10 mm and a current of 500 ± 10 μA for 11 days over 15 days (4 hours (h) per day). The integral of the current on the sample was 21.08 mAh. The target was primarily irradiated while the beam had a proton energy of 1.8 MeV, below the neutron generation threshold, and then irradiated for short periods at higher energies of 1.92–2.04 MeV to determine the neutron yield (see Figures 10B–10C).

[0092] Figure 10A is a graph depicting the relative number of blisters (y-axis) (relative number at the beam center) versus the irradiation time (x-axis), which is the time the beam was applied to target 602. Throughout the entire irradiation time, the surface of the sample being studied is captured using a KX InfiniMax with a Basler Ace acA4112-30uc CMOS camera and a Hikvision video camera. TMThe surface was monitored by a long-range microscope, and video signals were recorded. The appearance and disappearance of blisters were clearly observed in different parts of the target surface. Figure 11A is a macroscopic image of the lithium surface, and Figures 11B-11C are images taken by the long-range microscope on day 6 of irradiation. Figure 11A shows a dark band 1102 with a bandwidth of approximately 1 mm and an inner diameter of approximately 13 mm, coinciding with the position of the main power of the proton beam. Region 1104 corresponds to the center of target 802. Region 1106 corresponds to the peripheral region outside the main beam area 1102 that was further exposed to proton radiation. Region 1108 shows the target surface not irradiated by protons. Figure 11B is a close-up view showing region 1102 of the lithium target surface corresponding to the incidence by the center of the proton beam, and Figure 11C shows a close-up view of region 1106 of the lithium target surface on the periphery of the beam. The lithium surface was homogeneous at the center of the proton beam, and blisters However, while the blister is absent, it is clear that it is present around the beam.

[0093] Lithium surface modification by blistering was quantitatively determined as high-brightness regions in selected parts of the image. Computer processing was performed every 720 frames of the video signal file (approximately every 30 seconds). The processing distinguished the high-brightness regions corresponding to the blisters and determined the area of ​​these regions in two parts of the image, namely within the center of the beam and on its periphery. The results of processing the microscope video signal are shown in Figure 10A, where curve 1001 corresponds to the area of ​​the target surface impacted by the center of the beam, and curve 1002 corresponds to the area of ​​the target surface impacted by the periphery of the beam. Here, the Y axis is the relative amount of high-brightness area in selected parts of the image (within the center and on the periphery of the beam), and the X axis shows the sequence of processed image frames grouped by irradiation days over 11 different days out of 15 days. Most of the portion of curve 1001 showing the rise of blistering from time zero to peak value 1010 is omitted. To visualize the results, vertical lines separating one irradiation day from another are drawn on the plot. Since the beam output did not fluctuate during operation, the x-axis also generally corresponds to the proton fluence relative to target 802. The total time indicated by 1020 is approximately 42 hours.

[0094] Blister count data 1001 demonstrates that at time 1003, blister formation occurred at target 802, reaching a peak level of 1010. From time 1003 to time 1004, the blister count at target 802 decreased rapidly. As described with respect to the embodiment in Figure 4A-5, at time 1003, the lithium compound layer formed between the lithium layer 103 and the substrate 104 may have reached a sufficient depth to allow hydrogen to diffuse from the blister out of the body 102. Alternatively, as described with respect to the embodiment in Figure 6A-7, a transition from a crystalline structure to an amorphous structure may have occurred in the blister-forming material, such as the blister shell, and this shell, along with the penetrating lithium, may have been removed as a whole into the substrate. Alternatively, a combination of both may have occurred.

[0095] The following embodiments describe further mechanisms that may have contributed, in whole or in part, to the reduction of blister size and / or quantity. For example, proton beam exposure may induce convective forces to reduce blistering, such as by converting lithium from a solid to a localized liquid form (e.g., a hot spot), which allows hydrogen to escape and / or removes the blister shell into the substrate. In another embodiment, proton beam exposure may induce a capillary system of capillary forces to reduce blistering, such as by penetrating lithium into cracks, fissures, or other deformations in the substrate material, which allows hydrogen to escape and / or removes the blister shell into the substrate. A combination of convection and capillary action may also be a mechanism.

[0096] In the experiment, at time 1004, beam application was stopped for a time period and then immediately restarted. As a result of this stoppage, a short period of blister formation occurred from time 1004 to time 1005, at which point blister reduction began again, and the total number of blisters decreased to a level even lower than that present at time 1004. Similar cycles occurred at times 1006, 1007, 1008, and 1009. However, target 602 exhibited increased resistance to blister formation at the start of each cycle, so that the overall trend showed increased resistance to blister reduction and blister formation over time. The total number of blisters decreased to a count of nearly zero at the end of the experiment, which is a reduction of more than 99% from the peak. In other embodiments, the reduction may be slightly less, for example, more than 75%, more than 90%, or more than 95%.

[0097] Figures 10B and 10C are graphs plotting the neutron yield from target 602 on the y-axis versus the proton current integral Φ in milliampere-hours (mAh) on the x-axis. The data in Figure 10B are measured by a dosimeter and show the neutron dose rate D on the y-axis. The data in Figure 10C are measured by a neutron detector and show the count rate Y in units of per second on the y-axis. In these graphs, point 21 on the x-axis corresponds to 6.3 ± 0.6 × 10⁻⁶. 20 protons per square centimeter (p / cm) -2 ) corresponds to the proton fluence. Both graphs show that as the proton fluence increases, the neutron yield remains approximately constant, and that the neutron yield was generally in the range of 95–108 for the dosimeter in Figure 10B and 1,617–1,915 for the detector in Figure 10C. Point 21 also generally corresponds to point 1020 in Figure 10A. Thus, when blisters were formed, and when blisters were reduced and eliminated, the neutron yield remained approximately constant across their time periods. Thus, the neutron yield was generally unaffected by the presence of blisters. The lack of a decrease in neutron yield also indicates that hydrogen diffusing from the substrate 104 through the lithium layer 103 did not form hydrides or hydroxides with lithium or lithium copper (or formed only small or negligible amounts so as not to substantially reduce the neutron yield while blisters were forming and being eliminated). The proton fluence at point 21 can be expressed in terms of patient treatment. If this fluence is scaled to a target with an exposure area of ​​approximately 10 cm in diameter and used in conjunction with a proton beam having an energy of 2.3 MeV and a current of 10 milliamperes (mA), the fluence at point 21 would correspond to BNCT therapy for approximately 340 patients (assuming 40 minutes per patient).

[0098] In some of the embodiments described above, a technique is described in which the application of charged particle radiation to a metal body causes a first stage of blister formation in the body, followed by a second stage in which the blister is reduced in size or completely eliminated without requiring the formation of a lithium compound layer. Also described herein are embodiments in which there is a first stage of blister formation followed by a second stage of blister reduction or elimination using the formation of a lithium compound layer. Furthermore, embodiments described herein are in which there is a first stage of blister formation followed by a second stage of blister reduction or elimination using a transition of the substrate material from a crystalline state to a substantially amorphous state, either alone or in combination with a lithium compound layer. In addition to these embodiments described above, additional embodiments in which the lithium compound layer and / or amorphous material are typically formed prior to radiation exposure that would result in blister formation will be described here. These embodiments, with existing lithium compound layers and / or amorphous structures, have increased resistance to blister formation and, under certain conditions, completely prevent blister formation and thus avoid any residual, potentially undesirable structural deformation that may persist even after the blistering has been reduced and / or eliminated.

[0099] Embodiments of the metal body 102 described with respect to Figure 1D-1E can be processed prior to exposure to charged particle radiation such that a blister forms. For example, a lithium compound layer 105 can first be formed on or within the metal substrate 104, deposited on or bonded thereto, and then a lithium layer 103 can subsequently be formed on or within the lithium compound layer 105, deposited on or bonded thereto. Conversely, a lithium compound layer 105 can first be formed on or within the lithium layer 103, deposited on or bonded thereto, and then the metal substrate 104 can subsequently be formed on the lithium compound layer 105, deposited on or bonded thereto.

[0100] In another embodiment, the metal body 102 is first fabricated using a lithium layer 103 that is in direct contact with the substrate 104. The lithium of the layer 103 then contacts the substrate 104. The material can be exposed to one or more stimuli, such as heat, electricity, and / or pressure, over a specific period of time so that it diffuses into the material and forms a compound layer 105 in an area previously occupied only by the lithium layer, only by the metal substrate, or both. The conditions and duration for which one or more stimuli are applied can be used to determine the resulting thickness 112 of the compound layer 105.

[0101] The amorphous substrate 104 may have a lithium layer 103 on it, or it may be transitioned to an amorphous structure after the addition of the lithium layer 103. Similarly, the amorphous lithium compound layer 105 may also be provided according to the techniques described above, or it may be provided in a crystalline state and then transitioned to an amorphous state. The metal body 102 may then be used in the desired application with the existing amorphous structure.

[0102] The thickness 112 of the compound layer 105 and / or the amorphous portion of the body 102 may be selected to mitigate blister formation based on the expected conditions and nature of the radiation to which the body 102 will be exposed. For example, it may be desirable to form the compound layer 105 to a depth from the surface 204 that reaches the location where blister formation would otherwise occur under the expected radiation conditions. The depth of blister formation may depend on factors such as the type of radiation (e.g., protons, ions), the energy of the radiation, the purity of the substrate 104, the type of substrate metal, and others.

[0103] Embodiments of the metal body 102 with an existing lithium compound layer and / or an existing substantially amorphous structure can then be used in desired applications without blister formation or substantially without blister formation. For example, in a BNCT application where the lithium target 602 has an existing lithium compound layer (similar to Figure 8D) and / or an existing amorphous structure (similar to Figure 8E), a proton beam having an energy in the range of 1.9 MeV to 3.0 MeV (more preferably in the range of 2.3 MeV to 2.6 MeV) and a current in the range of 1 to 20 mA (more preferably in the range of 8 to 15 mA) can be applied to the target 602 over long time periods without blistering or substantially without blistering. Long time periods are, for example, at least 6.3 ± 0.6 × 10⁻⁶ 20 p / cm -2 This could be proton fluence.

[0104] While not limited to such embodiments, in many exemplary embodiments, the lithium layer may be 1 to 300 microns thick, and in some embodiments, 10 to 250 microns thick. While not limited to such embodiments, in many exemplary embodiments, if present, the lithium compound layer may be 1 to 500 microns thick, in some embodiments, 10 to 300 microns thick, and in some embodiments, 15 to 100 microns thick. While not limited to such embodiments, in many exemplary embodiments, if present, the amorphous portion of the substrate may be 1 to 500 microns thick, in some embodiments, 10 to 300 microns thick, and in some embodiments, 15 to 100 microns thick. While not limited to such embodiments, in many exemplary embodiments, the substrate may be at least 100 microns thick, and the maximum thickness depends on the application. In some embodiments, the substrate is 100 microns to 50 centimeters thick.

[0105] Various aspects of this subject matter are described below as a review of and / or complement to the embodiments described above, with the interrelationships and interchangeability of the following embodiments being emphasized here. In other words, it is emphasized that each feature of an embodiment can be combined with any other feature unless otherwise explicitly stated or logically impossible.

[0106] A first set of embodiments provides a method for operating a beam system having a target comprising a lithium layer and a metal substrate, the method comprising (a) exposing the target to charged particle radiation such that the target emits neutrons and a plurality of blisters are formed in the target, and (b) exposing the target to further charged particle radiation such that the target emits neutrons and the plurality of blisters are reduced in quantity and / or size.

[0107] In some embodiments, the charged particle radiation is a proton beam.

[0108] In some embodiments, (b) the step of exposing the target to further charged particle radiation such that the target emits neutrons and the number of blisters is reduced in quantity and / or size is performed per square centimeter (cm -2 ) at least 0.5 × 10 19 This includes a step of exposing the target to the proton energy fluence.

[0109] In some embodiments, the step of (b) exposing the target to further charged particle radiation includes exposing the target to further charged particle radiation until the amount of blistering is reduced by an order of magnitude.

[0110] In some embodiments, neutrons are at least 1 × 10⁻¹⁶ per second in steps (a) and (b). 12 It is emitted at the first rate of individual neutrons.

[0111] In some embodiments, the step of (a) exposing the target to charged particle radiation such that the target emits neutrons and a plurality of blisters are formed in the target further includes the step of applying the emitted neutrons to a human patient.

[0112] In some embodiments, the step of (b) exposing the target to further charged particle radiation such that the target emits neutrons and the number of blisters is reduced in quantity and / or size further includes the step of applying the emitted neutrons to a human patient.

[0113] In some embodiments, the emitted neutron reacts with p+ 7 Li→n+ 7 It is produced by the lithium layer according to Be.

[0114] In some embodiments, the method further includes the step of performing (a) and (b) as part of a boron neutron capture therapy (BNCT) procedure.

[0115] In some embodiments, the charged particle radiation is in the form of a beam, and the target is exposed to the charged particle radiation in steps (a) and (b) while the beam moves across the surface of the target in a direction transverse to the direction of beam propagation.

[0116] In some embodiments, (b) further includes the step of exposing the target to further charged particle radiation such that the target emits neutrons and the number of blisters is reduced in quantity and size.

[0117] In some embodiments, (b) further includes the step of exposing the target to further charged particle radiation such that the target emits neutrons and the number of blisters is reduced only in size.

[0118] In some embodiments, the metal substrate is copper. The lithium layer can be in contact with the copper substrate. The lithium layer can be formed directly on a copper bulk substrate.

[0119] In some embodiments, the lithium layer has a thickness ranging from 1 micron to 300 microns. It holds.

[0120] In some embodiments, the charged particle radiation has an energy in the range of 1.9 MeV to 3.0 MeV.

[0121] A second set of embodiments provides a method for operating a beam system having a target comprising a lithium layer and a metal substrate, the method comprising (a) exposing the target to charged particle radiation such that the target emits neutrons and a plurality of blisters are formed in the target, and (b) exposing the target to further charged particle radiation such that the target emits neutrons and the lithium compound layer is formed to a size sufficient to reduce the plurality of blisters between the lithium layer and the metal substrate in quantity and / or size.

[0122] In some embodiments, the charged particle radiation is a proton beam.

[0123] In some embodiments, (b) the step of exposing the target to further charged particle radiation such that the target emits neutrons and the number of blisters is reduced in quantity and / or size is performed per square centimeter (cm -2 ) at least 0.5 × 10 19 This includes a step of exposing the target to the proton energy fluence.

[0124] In some embodiments, the step of (b) exposing the target to further charged particle radiation includes exposing the target to further charged particle radiation until the amount of blistering is reduced by an order of magnitude.

[0125] In some embodiments, neutrons are at least 1 × 10⁻¹⁶ per second in steps (a) and (b). 12 It is emitted at the first rate of individual neutrons.

[0126] In some embodiments, the step of (a) exposing the target to charged particle radiation such that the target emits neutrons and a plurality of blisters are formed in the target further includes the step of applying the emitted neutrons to a human patient.

[0127] In some embodiments, the step of (b) exposing the target to further charged particle radiation such that the target emits neutrons and the number of blisters is reduced in quantity and / or size further includes the step of applying the emitted neutrons to a human patient.

[0128] In some embodiments, the emitted neutron reacts with p+ 7 Li→n+ 7 It is produced by the lithium layer according to Be.

[0129] In some embodiments, the method further includes the step of performing (a) and (b) as part of a boron neutron capture therapy (BNCT) procedure.

[0130] In some embodiments, the charged particle radiation is in the form of a beam, and the target is exposed to the charged particle radiation in steps (a) and (b) while the beam moves across the surface of the target in a direction transverse to the direction of beam propagation.

[0131] In some embodiments, (b) further includes the step of exposing the target to further charged particle radiation such that the target emits neutrons and the number of blisters is reduced in quantity and size.

[0132] In some embodiments, (b) further involves exposing the target to additional charged particle radiation such that the target emits neutrons and the number of blisters is reduced only in size. Includes pu.

[0133] In some embodiments, the metal substrate is copper, and the lithium compound layer is a lithium copper compound.

[0134] In some embodiments, the lithium layer has a thickness in the range of 1 micron to 300 microns.

[0135] In some embodiments, the charged particle radiation has an energy in the range of 1.9 MeV to 3.0 MeV.

[0136] A third set of embodiments provides a method for operating a beam system having a target comprising a lithium layer and a metal substrate, the method comprising (a) exposing the target to charged particle radiation such that the target emits neutrons and a plurality of blisters are formed in the target, and (b) exposing the target to further charged particle radiation such that the target emits neutrons and the metal substrate transitions from a crystalline state to an amorphous state sufficient to reduce the plurality of blisters in quantity and / or size.

[0137] In some embodiments, the charged particle radiation is a proton beam.

[0138] In some embodiments, (b) the step of exposing the target to further charged particle radiation such that the target emits neutrons and the number of blisters is reduced in quantity and / or size is performed per square centimeter (cm -2 ) at least 0.5 × 10 19 This includes a step of exposing the target to the proton energy fluence.

[0139] In some embodiments, the step of (b) exposing the target to further charged particle radiation includes exposing the target to further charged particle radiation until the amount of blistering is reduced by an order of magnitude.

[0140] In some embodiments, neutrons are at least 1 × 10⁻¹⁶ per second in steps (a) and (b). 12 It is emitted at the first rate of individual neutrons.

[0141] In some embodiments, the step of exposing the target to charged particle radiation such that the target emits neutrons and a plurality of blisters are formed in the target further includes applying the emitted neutrons to a human patient.

[0142] In some embodiments, the step of exposing the target to further charged particle radiation such that the target emits neutrons and a plurality of blisters are reduced in quantity and / or size further includes applying the emitted neutrons to a human patient.

[0143] In some embodiments, the emitted neutrons are generated by a lithium layer according to the reaction p + 7 Li → n + 7 Be.

[0144] In some embodiments, the method further includes performing (a) and (b) as part of a boron neutron capture therapy (BNCT) procedure.

[0145] In some embodiments, the charged particle radiation is in the form of a beam, and the target is exposed to the charged particle radiation in steps (a) and (b) while moving the beam across the surface of the target in a direction transverse to the direction of propagation of the beam.

[0146] In some embodiments, (b) further includes exposing the target to further charged particle radiation such that the target emits neutrons and a plurality of blisters are reduced in quantity and size.

[0147] In some embodiments, (b) further includes exposing the target to further charged particle radiation such that the target emits neutrons and a plurality of blisters are reduced in size only.

[0148] In some embodiments, the step of exposing the target to further charged particle radiation further includes exposing the target to further charged particle radiation such that a lithium compound layer is formed between the lithium layer and the metal substrate. The metal substrate can be copper, and the lithium compound layer can be a lithium copper compound. The step of exposing the target to further charged particle radiation can include exposing the target to further charged particle radiation such that the lithium compound layer is formed to a depth that reaches or is adjacent to a plurality of blisters between the lithium layer and the metal substrate.

[0149] In some embodiments, the lithium layer has a thickness within the range of 1 micron to 300 microns.

[0150] In some embodiments, the charged particle radiation has an energy within the range of 1.9 MeV to 3.0 MeV.

[0151] In a fourth set of embodiments, there is provided a method comprising: (a) exposing a region of a metal structure to charged particle radiation such that a plurality of deformations are formed within the region of the metal structure, the metal structure including a lithium layer; and (b) exposing the region of the metal structure to further charged particle radiation such that the plurality of deformations are reduced in quantity and / or size.

[0152] In some embodiments, the charged particle radiation is a proton beam.

[0153] In some embodiments, the step of exposing the region of the metal structure to further charged particle radiation includes exposing the region to further charged particle radiation until the amount of deformation is reduced by one order of magnitude.

[0154] 4]In some embodiments, the charged particle radiation is in the form of a beam, and the region is exposed to the charged particle radiation in steps (a) and (b) while moving the beam across the surface of the region in a direction transverse to the direction of propagation of the beam.

[0155] In some embodiments, the metal substrate is copper.

[0156] In some embodiments, the lithium layer is in contact with the copper substrate.

[0157] In some embodiments, the metallic structure is part of the plasma fusion reactor, and charged particle radiation is emitted from the fusion reaction.

[0158] In some embodiments, the lithium layer has a thickness in the range of 1 micron to 300 microns.

[0159] In some embodiments, the deformation is blister.

[0160] In some embodiments, the step of (b) exposing a region of the metallic structure to further charged particle radiation further includes exposing the region to further charged particle radiation such that convection and / or capillary forces reduce the multiple deformations in quantity and / or size.

[0161] A fifth set of embodiments provides a method comprising the steps of (a) exposing a region of a metallic structure to charged particle radiation so that a plurality of deformations are formed within the region of the metallic structure, wherein the metallic structure includes a lithium layer, and (b) further exposing a region of the metallic structure to charged particle radiation so that a lithium compound layer is formed between the lithium layer and the metallic substrate to a size sufficient to reduce the plurality of deformations in quantity and / or size.

[0162] In some embodiments, the charged particle radiation is a proton beam.

[0163] In some embodiments, the step of (b) exposing the region to further charged particle radiation includes exposing the region to further charged particle radiation until the amount of blistering is reduced by an order of magnitude.

[0164] In some embodiments, the charged particle radiation is in the form of a beam, and the region is exposed to the charged particle radiation in steps (a) and (b) while moving the beam across the surface of the region in a direction transverse to the direction of propagation of the beam.

[0165] In some embodiments, the metal substrate is copper and the lithium compound layer is a lithium copper compound.

[0166] In some embodiments, the lithium layer has a thickness within the range of 1 micron to 300 microns.

[0167] In some embodiments, the deformation is a blister.

[0168] In a sixth set of embodiments, (a) exposing a region of a metal structure to charged particle radiation such that a plurality of deformations are formed within the region of the metal structure, the metal structure including a lithium layer; and (b) further exposing the region of the metal structure to additional charged particle radiation such that the metal substrate transitions from a crystalline state to an amorphous state sufficient to reduce the plurality of deformations in amount and / or size. A method is provided.

[0169] In some embodiments, the charged particle radiation is a proton beam.

[0170] In some embodiments, step (b) of further exposing the region to additional charged particle radiation includes further exposing the region to additional charged particle radiation until the amount of blisters is reduced by one order of magnitude.

[0171] In some embodiments, the charged particle radiation is in the form of a beam, and the region is exposed to the charged particle radiation in steps (a) and (b) while moving the beam across the surface of the region in a direction transverse to the direction of propagation of the beam.

[0172] In some embodiments, the metal substrate is copper and the lithium compound layer is a lithium copper compound.

[0173] In some embodiments, the lithium layer has a thickness in the range of 1 micron to 300 microns.

[0174] In some embodiments, the deformation is blister.

[0175] In some embodiments, the step of (b) exposing the region to further charged particle radiation further includes the step of exposing the region to further charged particle radiation such that a lithium compound layer is formed between the lithium layer and the metal substrate.

[0176] In some embodiments, the metal substrate is copper, and the lithium compound layer is a lithium copper compound.

[0177] In some embodiments, the step of (b) exposing region to further charged particle radiation further includes exposing the target to further charged particle radiation such that a lithium compound layer is formed between the lithium layer and the metal substrate to a depth that reaches or is adjacent to a plurality of deformations.

[0178] In some embodiments, the step of (b) exposing a region of the metallic structure to further charged particle radiation further includes exposing the region to further charged particle radiation such that convection and / or capillary forces reduce multiple deformations in quantity and / or size.

[0179] In the seventh set of embodiments, the metal includes a metal substrate and a lithium-containing layer bonded to the metal substrate, wherein the metal body has at least 6.3 ± 0.6 × 10 20 protons per square centimeter (p / cm) -2 A metallic body is provided that is exposed to the charged particle fluence of ).

[0180] In some embodiments, the metal body exhibits resistance to blister formation that exceeds the resistance to blister formation exhibited prior to exposure.

[0181] In some embodiments, the metal substrate includes copper.

[0182] In some embodiments, the metal body further includes a lithium compound layer between the lithium-containing layer and the metal substrate. The lithium-containing layer may contain at least 90% lithium-7 isotopes. The lithium-containing layer may contain at least 98% lithium-7 isotopes.

[0183] In some embodiments, a first portion of the metal substrate is amorphous. A second portion of the metal substrate may be crystalline, and the first portion is relatively closer to the lithium-containing layer than the second portion.

[0184] In some embodiments, the metal body is configured for use in a plasma fusion reactor.

[0185] In some embodiments, the metal body is configured for use as a neutron generation target.

[0186] An eighth set of embodiments provides a metal body comprising a metal substrate and a layer containing lithium on the metal substrate, wherein one or more blisters are first formed in the metal body by charged particle radiation, and then one or more blisters are exposed to charged particle radiation to the extent that they are reduced in size by the charged particle radiation.

[0187] In some embodiments, the metal body resists blister formation exhibited prior to exposure. It exhibits resistance to blister formation that exceeds the resistance.

[0188] In some embodiments, the metal substrate includes copper.

[0189] In some embodiments, the metal body further includes a lithium compound layer between the lithium-containing layer and the metal substrate. The lithium-containing layer may contain at least 90% lithium-7 isotopes. The lithium-containing layer may contain at least 98% lithium-7 isotopes.

[0190] In some embodiments, a first portion of the metal substrate is amorphous. A second portion of the metal substrate may be crystalline, and the first portion is relatively closer to the lithium-containing layer than the second portion.

[0191] In some embodiments, the metal body is configured for use in a plasma fusion reactor or as a neutron generation target.

[0192] In a ninth set of embodiments, a target for use in boron neutron capture therapy (BNCT) is provided, the target comprising a copper substrate and a lithium-containing layer on the copper substrate, wherein one or more blisters are first formed in the target by charged particle radiation, and then one or more blisters are exposed to charged particle radiation so as to be reduced in size by the charged particle radiation.

[0193] In some embodiments, the target exhibits resistance to blister formation that exceeds the resistance to blister formation exhibited prior to exposure.

[0194] In some embodiments, lithium is in solid form.

[0195] In some embodiments, lithium is in liquid form.

[0196] In some embodiments, the target is per square centimeter (cm -2 ) at least 0.5 × 10 19The target is configured to generate neutrons without substantial blister formation in the copper substrate when exposed to proton radiation having an average energy of 1.9–3.0 megaelectron volts (MeV) and a current in the range of 1–20 milliamperes (mA) until proton fluence occurs. 7 Li→n+ 7 It can be configured to generate neutrons according to Be.

[0197] A tenth set of embodiments provides a target for use in boron neutron capture therapy (BNCT), comprising a first layer containing lithium, a copper substrate, and a second layer containing a lithium copper compound located between the first layer and the copper substrate, wherein the target is configured to generate neutrons when exposed to proton radiation.

[0198] In some embodiments, the target is configured to generate neutrons when exposed to proton radiation without substantial blister formation in the copper substrate.

[0199] In some embodiments, the target is configured to generate neutrons without substantial blister formation on the copper substrate when exposed to proton radiation having an average energy of 1.9 MeV to 3.0 MeV and a current in the range of 1 to 20 mA.

[0200] In some embodiments, the target is the reaction p+ 7 Li→n+ 7 It is configured to generate neutrons according to Be.

[0201] In some embodiments, the lithium layer has a thickness in the range of 1 to 300 microns.

[0202] An eleventh set of embodiments provides a target for use in boron neutron capture therapy (BNCT), comprising a first layer containing lithium and a copper substrate having a first portion in an amorphous state, wherein the target is configured to generate neutrons when exposed to proton radiation.

[0203] In some embodiments, the target is configured to generate neutrons when exposed to proton radiation without substantial blister formation in the copper substrate.

[0204] In some embodiments, the target is configured to generate neutrons without substantial blister formation on the copper substrate when exposed to proton radiation having an average energy of 1.9 MeV to 3.0 MeV and a current in the range of 1 to 20 mA.

[0205] In some embodiments, the target is the reaction p+ 7 Li→n+ 7 It is configured to generate neutrons according to Be.

[0206] In some embodiments, the first layer has a thickness in the range of 1 to 300 microns.

[0207] In some embodiments, the second portion of the copper substrate is in a crystalline state, and the first portion is relatively closer to the first layer containing lithium than the second portion.

[0208] In some embodiments, the target further includes a lithium copper compound layer between the first layer and the copper substrate.

[0209] It should be noted that all features, elements, components, functions, and steps described in relation to any embodiment provided herein are intended to be freely combined and substituted with those from any other embodiment. If a feature, element, component, function, or step is described in relation to only one embodiment, it should be understood that that feature, element, component, function, or step may be used in conjunction with all other embodiments described herein unless otherwise expressly stated. This paragraph therefore serves as a premise and descriptive aid for the introduction of claims that may, from time to time, combine features, elements, components, functions, and steps from different embodiments, or substitute features, elements, components, functions, and steps from one embodiment with those from another embodiment, even if the following description does not explicitly state that such combinations or substitutions are possible in particular cases. In particular, it is explicitly recognized that a clear enumeration of all possible combinations and substitutions would be undue burdensome, given that the permissibility of any such combinations and substitutions would be readily apparent to those skilled in the art.

[0210] As used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural nouns unless the context otherwise clearly determines.

[0211] The embodiments are subject to various modifications and alternative forms, specific examples of which are shown in the drawings and described in detail herein. However, it should be understood that these embodiments are not limited to any particular form disclosed, but rather encompass all modifications, equivalents, and alternatives that fall within the spirit of this disclosure. Furthermore, any feature, function, step, or element of an embodiment may not fall within its scope. Steps or elements, along with negative limitations that define the inventive scope of the claim, may be enumerated within or added to the claim.

Claims

[Claim 1] The invention described herein.

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