CN118175717B

CN118175717B - A curved solid-state accelerator neutron source target material and preparation method thereof

Info

Publication number: CN118175717B
Application number: CN202410231908.7A
Authority: CN
Inventors: 王盛; 李竞伦; 胡耀程
Original assignee: Huaboron Neutron Technology Hangzhou Co ltd
Current assignee: Huaboron Neutron Technology Hangzhou Co ltd
Priority date: 2023-07-07
Filing date: 2024-02-29
Publication date: 2024-12-06
Anticipated expiration: 2044-02-29
Also published as: CN118201185A; CN116785603A; CN118201185B; CN118175717A

Abstract

The invention relates to the technical field of engineering and discloses a curved surface solid accelerator neutron source target and a preparation method thereof. The neutron source target of the curved surface solid accelerator comprises a substrate structure and a target layer arranged on the upper surface of the substrate structure, wherein the target layer is curved. According to the invention, the target layer is arranged into a curved surface shape, and the design can effectively compensate thermal stress accumulation deformation of the target layer at high temperature, so that the integrity of the target layer at high temperature is ensured, and the service life of the target layer is finally and effectively prolonged.

Description

Curved surface solid accelerator neutron source target material and preparation method thereof

Technical Field

The invention relates to the technical field of engineering, in particular to a curved surface solid accelerator neutron source target and a preparation method thereof.

Background

Accelerator-based boron neutron capture therapy (Accelerator based boron neutron capture therapy, AB-BNCT) is a novel tumor radiotherapy modality that first requires the injection of a 10B-containing tumor targeted drug into a patient, and after the drug is enriched in the tumor region, the neutron beam is used to irradiate the tumor-containing region. The section of the capture reaction between 10B and neutrons is thousands times higher than that of human tissue elements, so that the neutrons can generate boron neutron capture reaction 10B (n, a) 7Li with boron drugs in tumor tissues. The secondary particles released by the reaction, alpha particles and 7Li ranges, are smaller than 1 cell diameter. Thus enabling precise destruction to occur inside the tumor cells. Compared with the traditional radiotherapy means, the method can kill cancer cells and simultaneously avoid the damage of normal tissue cells to the greatest extent, so that the treatment method has excellent targeting and has remarkable clinical application results.

The target is an important component of the AB-BNCT system, whose primary function is to generate neutrons required for treatment. The high-energy beam transport line is arranged at the tail end of the whole high-energy beam transport line and is positioned in front of the beam shaping body, protons accelerated by the RFQ reach a target station through the high-energy beam transport line, and the high-energy protons bombard the target to perform nuclear reaction so as to generate neutrons.

For targets (e.g., lithium targets, beryllium targets), irradiation with protons over time can result in reduced yield of the protons, and reduced neutron flux can directly affect the therapeutic effect of BNCT. In addition, in the process of shooting, the existing target material layer is easy to expand at high temperature due to the difference of thermal expansion coefficients of the target material layer, the substrate structure and the substrate layer, so that the target material layer is subjected to thermal stress accumulation and then deforms, and the service life of the target material is further reduced. Thus, the targets currently used for BNCT require replacement after a short period of irradiation. The shorter service life of the target greatly influences the planning of the treatment scheme and increases the running cost of BNCT facilities, which is not beneficial to the further popularization of the technology.

In view of this, there is a need for improvements in the prior art targets to address the above-described problems.

Disclosure of Invention

In order to solve the technical problems, the invention provides a curved solid accelerator neutron source target and a preparation method thereof. The invention designs the substrate layer and the target layer into curved surfaces with consistent curvature radius, and the design can effectively compensate the thermal stress accumulation deformation of the target layer at high temperature, thereby ensuring the integrity of the target layer at high temperature and finally effectively prolonging the service life of the target layer.

The specific technical scheme of the invention is as follows:

in a first aspect, the invention provides a neutron source target of a curved solid accelerator, which comprises a substrate structure, a substrate layer arranged on the upper surface of the substrate structure, a target layer arranged on the upper surface of the substrate layer, and a protective layer arranged on the periphery of the target layer. The substrate layer and the protective layer can be removed or reserved according to actual needs, and the substrate layer (if any) and the target layer are curved.

As described in the background art section of the application, because the thermal expansion coefficients of the existing target layer, the substrate structure and the substrate layer are different (for example, the thermal expansion coefficient of the lithium target layer is larger, and the thermal expansion coefficients of the copper substrate structure and the tantalum substrate layer are smaller), the target layer is easy to expand at high temperature in the process of shooting, so that the target layer is subjected to thermal stress accumulation and deformation, and the service life of the target layer is further reduced.

For this purpose, the invention provides the substrate layer (if any) and the target layer with curved surfaces. The inventor finds that the deformation of the target layer can be compensated by processing the surface of the basic structure into a deformed reverse curved surface shape in advance before plating the target layer, thereby ensuring the integrity of the target layer at high temperature and finally effectively prolonging the service life of the target layer.

Preferably, the curved surface is concave-convex (concave curved surface) when the thermal expansion coefficient of the substrate structure is smaller than that of the target layer, and is convex-concave (convex curved surface) when the thermal expansion coefficient of the substrate structure is larger than that of the target layer.

Preferably, the sagittal height of the target layer is p±10%:

In the present invention, the sagittal height refers to the vertical distance from a certain point on a curved surface to the lowest point (valley bottom) on the curved surface. Wherein P is the sagittal height to be compensated, T _f and T _s are the thickness of the target layer and the thickness of the substrate structure respectively, D is the diameter of the target layer, alpha _f and alpha _s are the thermal expansion coefficients of the target layer and the substrate structure respectively, T ₁ is the highest temperature of the target layer during targeting, and T ₀ is room temperature. Since the substrate layer (if any) is typically thin and has a small coefficient of thermal expansion, its thermal stress build-up is negligible here. The sagittal height is preferably determined to be within 10% of the P error.

Preferably, the target material layer is a lithium target layer or a beryllium target layer, and the material of the substrate layer is selected from tantalum, vanadium, palladium, platinum, titanium, niobium or alloys thereof.

Preferably, the shape of the surface of the side of the substrate structure, which is in contact with the target layer or the substrate layer (if any), matches the shape of the lower surface of the target layer or the substrate layer. The upper surface of the substrate structure is a convex curved surface if the lower surface of the target layer or the substrate layer is a concave curved surface, and is a concave curved surface if the lower surface of the target layer or the substrate layer is a convex curved surface.

Preferably, the shape of the surface of the side, which is contacted with the upper surface of the target layer, of the protective layer is matched with the shape of the upper surface of the target layer. The protective layer is a convex curved surface if the upper surface of the target layer is a concave curved surface, the protective layer is a concave curved surface if the upper surface of the target layer is a convex curved surface, and the other side of the protective layer can be a plane or a concave curved surface or a convex curved surface.

Preferably, the substrate layer and the target layer have a wafer structure and are arranged in concentric circles.

Preferably, the curvature radius of the substrate layer and the curvature radius of the target layer are identical.

In a second aspect, the invention provides a method for preparing a neutron source target of a curved solid accelerator, comprising the following steps of S1, preparing a substrate layer on the upper surface of a substrate structure;

S2, preparing a target layer on the upper surface of the substrate layer;

And S3, preparing a protective layer on the upper surface of the target layer.

Preferably, in S1, the substrate layer is prepared by a magnetron sputtering coating method, in S2, the target layer is prepared by a thermal evaporation deposition method, and in S3, the protective layer is prepared by a magnetron sputtering coating method.

Further preferably, in S2, the thermal evaporation deposition method specifically comprises the steps of placing a substrate into evaporation equipment, opening vacuum coating equipment, firstly pumping the pressure in a chamber to below 10Pa, then opening a molecular pump, pumping the pressure in the chamber to 8.0X10 ^-4 Pa after the molecular pump reaches the maximum rotation speed and stably operates, opening an evaporation source and a film thickness instrument, and starting coating after the evaporation rate is stable, opening a substrate baffle.

Compared with the prior art, the invention has the beneficial effects that the target layer is arranged into a curved surface shape, and the design can effectively compensate the thermal stress accumulation deformation of the target layer at high temperature, thereby ensuring the integrity of the target layer at high temperature and finally effectively prolonging the service life of the target layer.

Drawings

FIG. 1 is a cross-sectional view of a neutron source target of a curved solid state accelerator in the form of a concave curved surface in example 1 of the present invention (for ease of illustration, the layers of the layer are not shown to actual scale);

FIG. 2 is an overall schematic diagram of a neutron source target of a curved solid state accelerator according to embodiment 1 of the present invention (an anatomic diagram, for ease of illustration, layers of which are not shown to actual scale);

FIG. 3 is an exploded view of a curved solid state accelerator neutron source target in accordance with embodiment 1 of the invention;

FIG. 4 is a schematic diagram of a cooling component in a curved solid state accelerator neutron source target in accordance with embodiment 1 of the present invention;

FIG. 5 is a cross-sectional view of a neutron source target of a curved solid state accelerator in the form of a concave curved surface in example 2 of the present invention (for ease of illustration, the layers of the layer are not shown to actual scale);

FIG. 6 is an overall schematic diagram of a neutron source target of a curved solid state accelerator according to embodiment 2 of the present invention (anatomical diagram, layers of which are not shown to actual scale for ease of illustration);

fig. 7 is an exploded view of a curved solid state accelerator neutron source target in accordance with embodiment 2 of the invention.

The reference numerals comprise a 1-substrate structure, a 11-substrate structure upper shell, a 12-substrate structure lower shell, a 13-cooling component, a 2-substrate layer, a 3-lithium-blocking diffusion layer, a 4-target layer, a 5-protection layer, a 6-cooling medium liquid inlet and a 7-cooling medium liquid outlet.

Detailed Description

The present invention will be described in detail below with reference to the embodiments shown in the drawings, but it should be understood that the embodiments are not limited to the present invention, and functional, method, or structural equivalents and alternatives according to the embodiments are within the scope of protection of the present invention by those skilled in the art.

It should be understood that, in the present application, the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present technical solution and simplifying the description, and do not indicate or imply that the referred devices or elements must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present technical solution.

In particular, in the following examples, the principle of boron neutron capture therapy (Boron Neutron Capture Therapy, BNCT) is to destroy tumor cells by nuclear reaction occurring in tumor cells, first introduce a 10B-containing compound into a patient, because the compound has strong affinity with tumor cells, after entering the body, it is rapidly accumulated in tumor cells, while being distributed little in other normal tissues, then irradiate the tumor site with neutron beam to cause nuclear reaction between neutrons and 10B accumulated in tumor cells, after the neutron is captured by 10B, it generates an unstable composite nucleus 11B, which spontaneously breaks into an alpha particle with a kinetic energy of 1.78MeV and a 7Li recoil atomic nucleus with a kinetic energy of 1.01MeV (reaction cross section of 6.3%), or an alpha particle with a kinetic energy of 1.47MeV and a 7Li recoil atomic nucleus with a kinetic energy of 0.84MeV and emits photons with an energy of 0.48MeV (reaction cross section of 93.7%), and the 11B spontaneously breaks into an alpha particle with a kinetic energy of 1.78MeV by the following two reaction channels:

10B+nth→11B→7Li(1.01MeV)+4He(1.78MeV) 6.3%

10B+nth→11B→7Li(0.84MeV)+4He(1.47MeV)+γ(0.48MeV) 93.7%

The reaction product alpha particles and 7Li recoil atomic nuclei of the process have the characteristics of high linear energy conversion (LINEAR ENERGY TRANSFER, LET) and low oxygen enhancement ratio, can kill tumor cells with high selectivity and high strength, and simultaneously reduce the damage to surrounding normal tissues to the greatest extent.

The term "AB-BNCT" refers to accelerator-based boron neutron capture therapy (Accelerator based boron neutron capture therapy, AB-BNCT).

AB-BNCT is an accelerator-based boron neutron capture therapy technique that combines the principles of ion accelerator and boron neutron capture therapy, in which an ion accelerator is first used to generate a high energy ion beam, typically a proton or deuterium ion beam. These ion beams are accelerated to an energy and then implanted at high speed into a specific target, such as boride. When the ion beam interacts with the target, high energy neutrons are produced. The neutrons produced are directed to a tumor region within the patient, into which a boron-10 isotope-enriched compound has been injected. Boron-10 undergoes neutron capture reaction with the incident neutrons to produce energetic alpha particles and nuclear fission fragments, thereby effecting destruction of tumor cells.

Example 1 (without a lithium diffusion barrier layer)

1-3, The neutron source target of the curved surface solid accelerator comprises a substrate structure 1, a substrate layer 2 arranged on the substrate structure, a target layer 4 arranged on the substrate layer, a protective layer 5 arranged on the periphery of the target layer 4, wherein the substrate layer and the protective layer 5 are arranged on the periphery of the target layer 4 in a surrounding manner, and the substrate layer 2 and the target layer 4 are both arranged in a curved surface shape with consistent curvature radius (as shown in FIG. 1).

The substrate structure 1 is formed by splicing, clamping, welding or integrally forming the upper substrate structure shell 11 and the lower substrate structure shell 12, and materials of the substrate structure 1 can be selected from silicon substrates, quartz substrates, ceramic substrates, metal materials, such as Aluminum, copper, silver, nickel, iron, stainless steel, and the like, wherein the ceramic substrates comprise ceramic materials, such as Aluminum oxide (Aluminum), aluminum Nitride (Aluminum Nitride), and the like. Polymer substrate, polymer material such as Polyimide (Polyimide), polymethyl methacrylate (PMMA), etc. Of course, not limited to those listed. In view of cost and heat dissipation performance, copper is preferred in this embodiment.

As shown in fig. 4, the upper substrate structure case 11 is provided with a cooling member 13 for cooling the target layer, and the cooling member in the present application is not particularly limited, and is preferably an array type cooling structure including a cooling medium, a heat dissipating assembly for contacting the cooling medium, and the upper substrate structure case 11 accommodating the heat dissipating assembly, from the viewpoint of cooling efficiency. The cooling medium may be selected from cooling water, liquid nitrogen, and the like. Preferably, the arrangement of the heat dissipation assemblies is an array arrangement. The heat dissipation assembly is characterized in that a plurality of identical or similar heat dissipation assemblies are arranged together in an array mode. The heat dissipating components may be of the same size, shape, etc., or may be appropriately adjusted and optimized for particular needs. Preferably, the distance between the heat dissipating components is less than 5mm, more preferably the distance between the heat dissipating components is less than 2 mm. The heat dissipation component can be cylindrical or rectangular, and more preferably the heat dissipation component is cylindrical with a diameter of 2mm, and the heat dissipation component can be made of heat dissipation material, such as metal, and more specifically copper can be cited.

The array cooling structure can provide larger surface area and contact area, and heat transfer and heat dissipation capacity are enhanced. In addition, due to the close arrangement between the heat dissipating components, heat transfer is more uniform, helping to avoid the formation of hot spots.

As shown in fig. 3, the lower casing 12 of the substrate structure is provided with a cooling medium inlet 6 and a cooling medium outlet 7, respectively, and the cooling medium enters from the cooling medium inlet 6, flows in the space between the heat dissipation components, and then flows out through the cooling medium outlet 7.

The number of the cooling medium inlets 6 and the cooling medium outlets 7 is preferably 3 or more, and the design of 3 or more can make the flow of the cooling medium more uniform, so that the heat dissipation is more uniform, and the target layer 4 is prevented from melting under the irradiation of particles.

The substrate layer 2 (optionally, whether or not) disposed on the substrate structure may be made of tantalum, vanadium, palladium, platinum, titanium, niobium or an alloy thereof, and tantalum is a metal material with high corrosion resistance, high melting point and high thermal stability, and thus is used as the substrate layer in the present application. It is prepared by a magnetron sputtering coating method, i.e. a magnetron sputtering technique is used to deposit a thin film or coating on the substrate structure. The thickness of the substrate layer 2 may be selected from 10-40 μm (micrometers), more preferably 20 μm (micrometers) in this embodiment.

It should be noted that, the method of magnetron sputtering coating is known in the art, for example, in the magnetron sputtering process, an inert gas (such as argon) is used to form a low pressure environment, and then by applying a magnetic field, ionized particles are generated on the target, and these ionized particles are deposited on the substrate structure by sputtering on the surface of the target to form a substrate layer.

The metal tantalum substrate layer is prepared in a magnetron sputtering coating mode, so that a firm substrate can be provided for subsequent process steps, and the adhesive force and the structural stability of the substrate can be improved. Because the threshold value of hydrogen bubbling of the material of the substrate layer under proton bombardment is far higher than that of copper, the substrate layer mainly has the effect of enabling incident protons to stay in the layer finally and not enter the copper substrate structure, thereby preventing the hydrogen bubbling and prolonging the service life of the target. .

The target layer 4 provided on the substrate layer is preferably a lithium target in this embodiment, but the protective scope is not limited to a lithium target, for example, a beryllium target still constitutes an equivalent arrangement to a lithium target without departing from the concept of the invention.

Lithium targets are preferred in this embodiment because they require lower proton energies to produce the desired neutrons than beryllium targets.

For the target, the irradiation of protons over a period of time results in a decrease in their yield and a decrease in neutron flux, which directly affects the therapeutic effect of AB-BNCT. The targets currently used for AB-BNCT therefore need to be replaced after a short irradiation time. The shorter service life of the target material influences the planning of the treatment scheme and improves the running cost of the AB-BNCT equipment. Unfavourable popularization of AB-BNCT therapy. The factor influencing neutron yield is the thickness of the target layer, which can be reduced and uneven during the process of proton bombardment of the target layer, such as sputtering of the target layer under proton bombardment, interdiffusion of the target layer and the substrate layer when the temperature rises, and the like, and a series of factors reduce the service life of the target layer.

Meanwhile, as the melting point of lithium is low, heat accumulation caused by proton irradiation can cause the temperature of the substrate layer to rise if the heat cannot be taken away in time, so that the target layer is melted, and the service life of the target layer is reduced.

In addition, in the invention, the target material layer is prepared by adopting a thermal evaporation deposition mode.

The method specifically comprises the following steps of placing a substrate into evaporation equipment, opening vacuum coating equipment, firstly pumping the pressure in a chamber to below 10Pa, then opening a molecular pump, pumping the pressure in the chamber to 8.0X10 ^-4 Pa after the molecular pump reaches the highest rotating speed and stably operates, opening an evaporation source and a film thickness instrument, and starting coating after the evaporation rate is stable.

The method comprises the following steps of:

Preparing a substrate, namely placing the substrate to be coated into evaporation equipment. The substrate is cleaned in advance to ensure clean, dust-free and impurity-free surface.

Opening the vacuum coating equipment, namely opening the evaporation equipment and ensuring the sealing of the cavity.

And vacuumizing, namely vacuumizing the pressure in the cavity to be less than 10Pa by using a vacuum pump. Most of the gas is usually exhausted using a mechanical pump before the pressure is further reduced using a molecular pump.

Starting the molecular pump, namely opening the molecular pump, regulating the rotating speed of the molecular pump, and gradually reaching the highest rotating speed and stably operating the molecular pump. The function of the molecular pump is to further reduce the pressure in the chamber.

And further vacuumizing, namely, the pressure in the cavity is further pumped to about 8.0 multiplied by 10 ^-4 Pa by utilizing the action of a molecular pump. The higher vacuum condition helps to reduce collisions of gas molecules, providing a better deposition environment.

The evaporation source and the film thickness gauge are turned on, and the lithium target is heated to the evaporation temperature, usually by a heating source. And meanwhile, the film thickness meter is opened and used for monitoring the thickness of the coating film in real time.

And stabilizing the evaporation rate, namely waiting for the stabilization of the evaporation rate after the evaporation source begins to heat.

And opening the substrate baffle, namely opening the substrate baffle after the evaporation rate is stable, and starting to deposit lithium particles on the substrate by evaporation. The substrate barrier serves to block lithium particles before the evaporation source is turned on to avoid contaminating the substrate.

And (3) coating, namely after the substrate baffle is opened, depositing lithium particles on the surface of the substrate. The evaporation source and the film thickness meter will continuously work to maintain a stable evaporation rate and monitor the thickness of the coating film.

The film prepared by the thermal evaporation deposition method often shows tensile stress, and because the thermal expansion coefficient of lithium is larger, if the thermal expansion coefficients of the substrate structure and the substrate layer are smaller, the lithium film expands when the temperature of the lithium film is increased due to the bombardment of the lithium target by protons, so that the lithium film is subjected to compressive stress, and then deforms, and the service life of the lithium target layer is further reduced.

In order to solve the technical problem, the inventor of the present application further improves the design, and sets the substrate layer, the lithium diffusion barrier layer and the lithium target layer to be curved surfaces with consistent curvature radius, specifically, as shown in fig. 1, the curved surfaces can be designed to be concave curved surfaces or convex curved surfaces according to the situation (if the thermal expansion coefficient of the substrate structure is smaller than that of the target layer, the curved surfaces are concave curved surfaces with concave upper part and concave lower part, and if the thermal expansion coefficient of the substrate structure is greater than that of the target layer, the curved surfaces are convex curved surfaces with concave upper part and concave lower part), and the inventor discovers that when the compressive stress exceeds the limit of the lithium thin film, the thin film can be buckled. The substrate layer is pre-processed into the shape opposite to the deformation of the film before film coating, so that the deformation of the lithium film can be compensated, and the integrity of the lithium film at high temperature is ensured.

In this embodiment, as shown in fig. 3, a concave curved surface is preferable, and the curved surface sagittal height is calculated by the following formula (allowable error±10%):

Wherein P is the sagittal height to be compensated, T _f and T _s are the thickness of the target layer and the thickness of the substrate structure respectively, D is the diameter of the target layer, alpha _f and alpha _g are the thermal expansion coefficients of the target layer and the substrate structure respectively, T ₁ is the highest temperature of the target layer during targeting, and T _o is the room temperature. The thermal stress build-up is negligible here due to the thin substrate layer thickness and small thermal expansion coefficient. The preferred range of the rise of the concave curved surface is 120-200 microns, and in this embodiment, is more preferably 150 microns. "sagittal height of a concave surface" refers to the vertical distance from a point on the surface to the lowest point (valley) on the surface.

As shown in fig. 2, in this embodiment, the substrate layer and the target layer disposed on the substrate layer are in a wafer structure and are disposed in concentric circles. Of course, other shapes are possible, and the invention is not limited to wafer structural designs.

And the protective layer 5 is arranged on the periphery of the target layer 4, and the substrate layer and the protective layer 5 are arranged on the periphery of the target layer in a surrounding manner to cover the target layer 4.

The protective layer 5, firstly, is used for avoiding sputtering of the target layer caused by proton bombardment, and can be used as a physical isolation layer to reduce the influence of sputtering and corrosion. Secondly, the integrity of the target layer is protected, and impurities, gas or liquid in the external environment can be prevented from entering the target layer by the protective layer, so that the integrity and purity of the target layer are ensured. And thirdly, structural support can be provided for the curved solid target, the overall stability and strength are enhanced, and the influence of external vibration or stress on the target layer is reduced.

The protective layer 5 is generally made of a material having high heat resistance, corrosion resistance and chemical stability to ensure reliability and durability under the environment of proton bombardment or the like. Common material choices include metals (e.g., stainless steel, titanium alloys), ceramics (e.g., aluminum oxide, silicon nitride), or high temperature polymers (e.g., polyimide), among others.

Further preferably, the protective layer may be selected from carbide ceramics, nitride ceramics or high entropy alloys.

Examples of the carbide ceramic include zirconium carbide, silicon carbide, titanium carbide, tungsten carbide, boron carbide, aluminum carbide, silicon nitride carbide, molybdenum carbide, niobium carbide, hafnium carbide, chromium carbide, tantalum carbide, and vanadium carbide.

The nitride ceramics include any one or a combination of a plurality of silicon nitride, aluminum nitride, titanium nitride, molybdenum nitride, and tungsten nitride.

Most preferably, the protective layer in this embodiment is preferably zirconium carbide.

The applicant finds that the protective layer is preferably zirconium carbide covered on the surface of the target material layer, so that sputtering caused by proton bombardment can be avoided, the integrity of the target material layer can be maintained, the protective layer has a good irradiation-resistant effect, and the effectiveness of the protective layer can be maintained under the environment of proton bombardment.

The shape of the side of the protective layer 5 contacting the target layer 4 is matched with the target layer 4, that is, a convex curved surface is presented, and the other side of the protective layer 5 may be a plane, a concave curved surface or a convex curved surface.

The preparation method of the neutron source target material of the curved solid accelerator comprises the following steps:

preparing a substrate structure, wherein a cooling component is arranged in the substrate structure;

processing one side of the substrate structure into a concave curved surface according to a preset curvature, and sequentially preparing a substrate layer, a target layer and a protective layer on the concave curved surface;

the substrate layer is prepared by a magnetron sputtering coating method;

the target material layer is prepared and obtained by a thermal evaporation deposition method;

the protective layer is prepared by a magnetron sputtering coating method, and the substrate layer and the protective layer are arranged on the periphery of the target layer in a surrounding mode.

In a preferred embodiment, the substrate layer is coated by magnetron sputtering by forming a low pressure environment using an inert gas (such as argon) during the magnetron sputtering process, and then generating ionized particles on the target by applying a magnetic field, wherein the ionized particles are deposited on the substrate structure by sputtering on the surface of the target to form the substrate layer.

Preferably, the substrate layer is prepared and obtained by a magnetron sputtering coating method, and the specific conception is as follows:

(1) The equipment is prepared by preparing the magnetron sputtering equipment, ensuring the normal operation and vacuum state of the equipment, and ensuring that target materials (such as tantalum or molybdenum) in the equipment are installed on the target gun.

(2) Target preparation, cutting target material into blocks of proper size, cleaning and placing on a target gun of a magnetron sputtering device.

(3) Vacuum pumping, namely starting the magnetron sputtering equipment, and pumping the pressure in the cavity to be lower than the required vacuum degree (generally between 10 ^-4-10^-6 Pa).

(4) Gas injection, in which an inert gas (such as argon) is injected into the chamber to establish an inert atmosphere and maintain a stable operating pressure.

(5) And adjusting the position and angle of the target gun to align the target gun with the substrate layer.

(6) Sputtering target material, namely energizing a target gun to generate high-energy particle beams to strike target material. Atoms in the target material are struck and deposited on the substrate layer to form a lithium diffusion barrier.

(7) And controlling the film thickness, namely controlling and adjusting the film thickness of the lithium-resistant diffusion layer by controlling the sputtering time and the power and monitoring the film thickness (such as a film thickness meter).

(8) And (3) ending sputtering, namely stopping electrifying the target gun after the required sputtering time is finished, and ending the sputtering process.

The method specifically comprises the steps of placing a substrate in evaporation equipment, opening vacuum coating equipment, pumping the pressure in a chamber to below 10Pa, then opening a molecular pump, pumping the pressure in the chamber to 8.0X10 ^-4 Pa after the molecular pump reaches the highest rotating speed and stably operates, opening an evaporation source and a film thickness instrument, opening a substrate baffle after the evaporation rate is stable, and starting coating.

Example 2 (including lithium diffusion barrier layer)

The embodiment provides another curved solid state accelerator neutron source target, as shown in fig. 5-7, which is different from embodiment 1 in that the curved solid state accelerator neutron source target further comprises a lithium-blocking diffusion layer 3, specifically comprising a substrate structure 1 (copper), a substrate layer 2 (tantalum) arranged on the substrate structure, the substrate structure 1 being contacted with the substrate layer 2, the lithium-blocking diffusion layer 3 arranged on the substrate layer, the other side (namely, the opposite side contacted with the substrate structure 1) of the substrate layer 2 being contacted with the lithium-blocking diffusion layer 3, a target layer 4 (lithium target) arranged on the lithium-blocking diffusion layer 3, the lithium-blocking diffusion layer 3 being contacted with the target layer 4, and a protective layer 5 arranged on the periphery of the target layer 4, wherein the lithium-blocking diffusion layer 3 and the protective layer 5 are arranged around the periphery of the target layer 4.

Wherein the substrate layer, the lithium-resistant diffusion layer and the target layer are curved surfaces with consistent curvature radius (concave curved surfaces with concave upper part and convex lower part, and the dimensional parameters of each layer except the lithium-resistant diffusion layer are the same as those of the example 1, and the sagittal height of the lithium-resistant diffusion layer is the same as that of the target layer).

In this embodiment, the lithium-blocking diffusion layer is used to prevent diffusion of lithium in the target layer from escaping the target layer while maintaining the integrity and stability of the target layer. The lithium diffusion barrier layer is typically selected from materials having a relatively high resistance to lithium diffusion and chemical stability. For example, the material is a metal or an alloy, such as tantalum (Ta) or molybdenum (Mo), which has a low diffusion coefficient and a high corrosion resistance. These materials hinder the diffusion of lithium by forming a barrier layer between the target layer and other environment. When the material of the substrate layer is the same as that of the lithium diffusion barrier layer (for example, tantalum), the substrate layers may be combined into the same layer.

The inventors found that the replacement of the lithium-resistant diffusion layer with rare earth metal oxides such as silicon carbide, aluminum nitride, yttrium oxide, erbium oxide, etc. has a better effect of preventing the diffusion of lithium. The target material is not easy to diffuse at high temperature, so that the integrity of the lithium layer is maintained, and the reduction of the thickness of the lithium film is avoided.

Alternatively, the lithium-blocking diffusion layers 3 may each be provided as a silicon carbide layer. The thickness of the lithium-ion-resistant diffusion layer 3 is not too thick, preferably less than 5 μm (micrometers), and most preferably 1 μm (micrometers) in this embodiment, and if the lithium-ion-resistant diffusion layer 3 is too thick, the lithium ion transmission path becomes long, the transmission resistance and time are increased, and the diffusion rate of lithium ions in the target layer is reduced. In addition, an excessively thick lithium diffusion barrier layer may generate a large stress difference, resulting in structural deformation. In order to solve the technical problem, on the one hand, the thickness of the lithium-resistant diffusion layer 3 is set, on the other hand, the thickness ratio of the substrate layer 2, the lithium-resistant diffusion layer 3 and the target material layer 4 is controlled to be (10-40) to 1 (140-160), and further preferably, when the substrate layer is made of tantalum or palladium, the thickness ratio of the substrate layer, the lithium-resistant diffusion layer and the lithium target layer is set to be (18-22) to 1 (140-160), when the substrate layer is made of vanadium, the thickness ratio of the substrate layer, the lithium-resistant diffusion layer and the lithium target layer is set to be (27-33) to 1 (140-160), when the substrate layer is made of platinum, the thickness ratio of the substrate layer, the lithium-resistant diffusion layer and the lithium target layer is set to be (13-17) to 1 (140-160), when the substrate layer is made of titanium, the thickness ratio of the substrate layer, the lithium-resistant diffusion layer and the lithium target layer is set to be (31-39) to 1 to 140-160), and when the substrate layer is made of vanadium, the substrate layer is made of niobium, the thickness ratio of the substrate layer is set to be (22 to be 1 to 140-160). In this embodiment, the substrate layer is tantalum, and the thickness ratio of the substrate layer, the lithium diffusion barrier layer and the lithium target layer is preferably 20:1:150. The preparation method of the neutron source target material of the curved solid accelerator comprises the following steps:

Processing one side of the substrate structure into a concave curved surface according to a preset curvature, and sequentially preparing a substrate layer, a lithium diffusion resistance layer, a target layer and a protective layer on the concave curved surface;

the substrate layer and the lithium-resistant diffusion layer are prepared and obtained by a magnetron sputtering coating method;

The protective layer is prepared by a magnetron sputtering coating method, and the lithium-resistant diffusion layer and the protective layer are arranged on the periphery of the target layer in a surrounding mode.

Example 3 (target layer is beryllium target layer)

The present embodiment provides another curved solid state accelerator neutron source target, which is different from embodiment 1 in that the target layer is a beryllium target layer, the substrate structure is also copper, and since the coefficient of thermal expansion of beryllium is smaller than that of copper, the upper surface of the substrate structure needs to be processed into a convex curved surface, i.e. the substrate layer and the beryllium target layer are curved surfaces with concave upper part and concave lower part, and the sagittal height is also calculated by the following formula (allowable error±10%):

Example 4 (no substrate layer)

The present embodiment provides another curved solid state accelerator neutron source target, which differs from embodiment 1 only in that no substrate layer is provided, i.e. the target layer is directly deposited on the surface of the substrate structure.

The raw materials and equipment used in the invention are common raw materials and equipment in the field unless otherwise specified, and the methods used in the invention are common methods in the field unless otherwise specified.

The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and any simple modification, variation and equivalent transformation of the above embodiment according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. The neutron source target of the curved solid accelerator is characterized by comprising the following components:

A substrate structure;

A substrate layer disposed on the upper surface of the substrate structure;

The lithium-resistant diffusion layer is arranged on the upper surface of the substrate layer;

The target material layer is arranged on the upper surface of the lithium-resistant diffusion layer and is a lithium target layer;

the substrate layer, the lithium diffusion resistance layer and the target material layer are in a curved surface shape;

the material of the lithium-resistant diffusion layer is selected from one or more of silicon carbide, aluminum nitride, yttrium oxide, erbium oxide, tantalum and molybdenum;

the thickness ratio of the substrate layer, the lithium diffusion resistance layer and the lithium target layer is (10-40) 1 (140-160).

2. The curved solid state accelerator neutron source target of claim 1, wherein:

The thermal expansion coefficient of the substrate structure is smaller than that of the target layer, the curved surface is concave and convex, or

The thermal expansion coefficient of the substrate structure is larger than that of the target layer, and the curved surface is concave and convex.

3. The curved solid state accelerator neutron source target according to claim 1 or 2, wherein the sagittal height of the target layer is P+ -10%:

Wherein P is the sagittal height, T _f and T _s are the thicknesses of the target layer and the substrate structure respectively, D is the diameter of the target layer, alpha _f and alpha _s are the thermal expansion coefficients of the target layer and the substrate structure respectively, T ₁ is the highest temperature of the target layer during shooting, and T ₀ is the room temperature.

4. The curved solid state accelerator neutron source target of claim 1, wherein the substrate layer is made of a material selected from the group consisting of tantalum, vanadium, palladium, platinum, titanium, niobium and alloys thereof.

5. The curved solid state accelerator neutron source target of claim 1, wherein the substrate layer, the lithium-resistant diffusion layer and the target layer have a uniform radius of curvature.

6. The curved solid state accelerator neutron source target of claim 1, wherein a protective layer is arranged outside the target layer.

7. The curved solid state accelerator neutron source target of claim 1, wherein the thickness of the lithium-resistant diffusion layer is <5 microns.

8. The curved solid state accelerator neutron source target of claim 1, wherein:

The substrate layer is made of tantalum or palladium, and the thickness ratio of the substrate layer, the lithium diffusion resistance layer and the lithium target layer is (18-22): 1 (140-160); or

The substrate layer is made of vanadium, and the thickness ratio of the substrate layer, the lithium diffusion resistance layer and the lithium target layer is (27-33): 1 (140-160), or

The substrate layer is made of platinum, and the thickness ratio of the substrate layer, the lithium diffusion resistance layer and the lithium target layer is (13-17): 1 (140-160), or

The substrate layer is made of titanium, and the thickness ratio of the substrate layer, the lithium diffusion resistance layer and the lithium target layer is (31-39): 1 (140-160), or

The substrate layer is made of niobium, and the thickness ratio of the substrate layer, the lithium diffusion resistance layer and the lithium target layer is (22-28) 1 (140-160).

9. A method for preparing a curved solid state accelerator neutron source target according to claim 1, comprising the steps of:

s1, preparing a substrate layer on the upper surface of a substrate structure;

s2, preparing a lithium-resistant diffusion layer on the upper surface of the substrate layer;

s3, preparing a target layer on the upper surface of the lithium-resistant diffusion layer;

And S4, preparing a protective layer on the upper surface of the target layer.

10. The method of manufacturing according to claim 9, wherein:

In S1, the substrate layer and the lithium-resistant diffusion layer are prepared and obtained by a magnetron sputtering coating method;

S2, preparing the target material layer by a thermal evaporation deposition method;

and S3, preparing the protective layer by a magnetron sputtering coating method.