CN220823344U

CN220823344U - Target structure for accelerator neutron source

Info

Publication number: CN220823344U
Application number: CN202321795535.3U
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: 2023-07-07
Publication date: 2024-04-19
Anticipated expiration: 2033-07-07

Abstract

The utility model relates to the technical field of engineering, in particular to a target structure for an accelerator neutron source, and specifically discloses a target structure for an accelerator neutron source, which sequentially comprises the following components: a substrate layer, a barrier layer, a target layer, and a protective structure; the barrier layer and the protection structure are arranged on the periphery of the target layer in a surrounding mode; the thickness of the substrate layer is greater than that of the barrier layer; the barrier layer is contacted with the target layer; and the barrier layer is configured to inhibit diffusion of the target layer. The target structure has longer service life.

Description

Target structure for accelerator neutron source

Technical Field

The utility model relates to the technical field of engineering, in particular to a target structure for a neutron source of an accelerator.

Background

Accelerator-based boron neutron capture therapy (Accelerator based boron neutron capture therapy, AB-BNCT) is an innovative approach to tumor radiotherapy. The basic principle of the treatment method is that a tumor targeting drug containing 10B is firstly injected into a patient. After the drug has accumulated in the tumor area, the area with the tumor is irradiated with a neutron beam. Since the capture reaction of 10B with neutrons is much higher than other elements in human tissue, neutrons will undergo a boron neutron capture reaction of 10B (n, a) 7Li with boron drugs in tumor tissue. The range of secondary particles alpha particles and 7Li generated by the reaction is smaller than 1 cell diameter, so that the accurate damage to tumor cells is realized. Compared with the traditional radiotherapy means, the AB-BNCT can kill cancer cells and simultaneously minimize the damage to normal tissue cells, so that the AB-BNCT has excellent targeting property and has obvious effects in clinical application.

However, there are challenges in targets (e.g., lithium targets, beryllium targets) used in AB-BNCT. Over time, the neutron yield of the target after exposure to protons may decrease, resulting in a decrease in neutron flux. This directly affects the effect of BNCT treatment. Currently, the target for BNCT needs to be replaced in a short time, and the shorter service life of the target seriously influences the planning of a treatment scheme and increases the running cost of BNCT facilities. This has an adverse effect on the further popularization of the AB-BNCT technology.

Therefore, there is a need to develop a target structure that maintains adequate neutron yield and flux after proton irradiation, and extends the target lifetime to reduce the complexity and running cost of the treatment regimen. The target structure needs to stably generate neutrons, can continuously provide required neutron flux, improves the curative effect in BNCT treatment, and promotes the wide application of AB-BNCT technology.

Disclosure of utility model

The utility model aims to disclose a target structure for an accelerator neutron source, which is used for solving the technical problems of short service life and the like of the target structure in the prior art.

In order to achieve the above object, the present utility model provides a target structure for an accelerator neutron source, the target structure comprising, in order: a substrate layer, a barrier layer, a target layer, and a protective structure;

The barrier layer and the protection structure are arranged on the periphery of the target layer in a surrounding mode;

The thickness of the substrate layer is greater than that of the barrier layer; the barrier layer is contacted with the target layer; and the barrier layer is configured to inhibit diffusion of the target layer.

As a further improvement of the present utility model, a substrate structure is provided on a side of the substrate layer opposite to a side in contact with the barrier layer, and a cooling member is provided inside the substrate structure; the cooling component is used for reducing the temperature of the target layer.

As a further improvement of the utility model, the thickness ratio of the target layer to the protective structure is (50-250): 1.

As a further improvement of the utility model, the cooling component is an array type cooling structure, the array type cooling structure comprises a cooling medium, a cooling component for the cooling medium to contact and a substrate for accommodating the cooling component, and the substrate structure is provided with a liquid inlet and a liquid outlet.

As a further improvement of the present utility model, the cooling medium includes any one of water, liquid nitrogen, an amine-based coolant, a cooling oil, and a polymer coolant.

As a further improvement of the utility model, the heat dissipation component is any one of a cylinder, a cuboid and a cube.

As a further improvement of the utility model, the heat dissipation components are arranged in an array, and the distance between the heat dissipation components is less than 5 mm.

As a further improvement of the utility model, the substrate layer and the target layer are both arranged in a wafer structure and are arranged in concentric circles.

As a further improvement of the utility model, the target structure is arranged in a curved surface shape, the substrate layer and the target layer are both arranged in a concave curved surface shape with consistent curvature radius, and the sagittal height of the concave curved surface is smaller than 1 micrometer.

The second aspect of the utility model provides an accelerator neutron source, comprising the target structure.

Compared with the prior art, the utility model has the beneficial effects that:

1. Through setting up barrier layer and protection architecture, in the in-process of proton bombardment target, can effectually reduce the reduction of target layer thickness and the phenomenon of the inhomogeneous of target layer that causes because of proton bombardment.

2. By providing cooling means, the lifetime of the target structure can be increased. The cooling component can avoid the target material layer, such as a lithium target or a beryllium target, and the heat accumulation caused by proton irradiation can cause the temperature rise of the substrate layer to melt if the heat accumulation cannot be taken away in time due to the lower melting point of lithium, so that the service life of the target material structure is reduced.

Drawings

FIG. 1 is a schematic view of a target structure according to the present utility model;

FIG. 2 is an exploded view of the target structure of FIG. 1;

FIG. 3 is a schematic diagram of a cooling component array cooling structure;

1-a substrate structure; 11-a substrate structural upper housing; 12-a substrate structure lower housing; 13-cooling the component; 2-a substrate layer; 3-a lithium-blocking diffusion layer; a 4-lithium target layer; 5-a protective housing; 6, a cooling medium inlet; 7-a cooling medium water outlet.

Detailed Description

The present utility model 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 utility model, and functional, method, or structural equivalents and alternatives according to the embodiments are within the scope of protection of the present utility model 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 examples that follow, the term "AB-BNCT" refers to accelerator-based boron neutron capture therapy (Accelerator based boron neutron capture therapy, AB-BNCT).

The accelerator neutron source bombards a target material with a particle beam through an accelerator, and generates neutrons by nuclear reaction, and the reaction formula is as follows:

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 nucleus of the process have the characteristics of high linear energy conversion 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 target structure of the accelerator neutron source refers to a target material used in a neutron source device and corresponding structural design thereof for generating neutrons, and is a key device for realizing neutron generation and release.

One embodiment of a target structure for an accelerator neutron source is disclosed in the present utility model provided with reference to fig. 1-3.

A target structure for an accelerator neutron source, the target structure comprising in order: a substrate layer 2, a barrier layer 3, a target layer 4 and a protection structure 5; wherein the substrate layer 2 is in contact with the barrier layer 3; the barrier layer 3 is in contact with the target layer 4; the target layer 4 is in contact with the protective structure 5; the barrier layer 3 and the protection structure 5 are arranged around the periphery of the target layer, seal the target layer 4 and block the contact with the outside.

Substrate layer 2

The material of the substrate layer 2 may be selected from tantalum, which is a corrosion-resistant, high-melting-point and high-thermal-stability metal material, and thus is used as the substrate layer in the present application. The thickness for the substrate layer 2 may be selected from 10-30 μm (micrometers), more preferably 20 μm (micrometers).

It should be noted that, the metal tantalum substrate layer prepared by magnetron sputtering coating can provide a firm substrate for the subsequent process steps, and can enable the adhesion and structural stability of the substrate. And the metal tantalum substrate layer can be used for absorbing protons penetrating through the lithium target layer and preventing the protons from directly entering the cooling component so as to damage the substrate structure.

In a preferred embodiment, a substrate structure 1 is arranged on the opposite side of the substrate layer 2 to the side contacting the barrier layer 3, and a cooling component is arranged inside the substrate structure 1; the cooling member 13 serves to reduce the temperature of the target layer.

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 the materials of the substrate structure 1 can be selected from the following materials: silicon substrate, quartz substrate, ceramic substrate: ceramic materials such as Alumina (Aluminum), aluminum Nitride (Aluminum Nitride), etc., metal substrates: metallic materials such as aluminum, copper, silver, nickel, iron, stainless steel, and the like. A polymer substrate: polymeric materials such as Polyimide (Polyimide), polymethyl methacrylate (PMMA), and the like. Of course, not limited to those listed. In view of cost and heat dissipation performance, copper is preferred in this embodiment.

The cooling member 13 for cooling the lithium target layer 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 substrate structure lower case 12 accommodating the heat dissipating assembly, in view of cooling efficiency, provided on the substrate structure lower case 12. 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 5 mm, more preferably the distance between the heat dissipating components is less than 2 mm. The heat dissipation assembly may be selected to be a cylinder or a cuboid or a cube or the like, and more preferably, the heat dissipation assembly is a cylinder with a diameter of 2 mm.

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. 2, the upper casing 11 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, then 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 liquid inlets 6 and the cooling medium water outlets 7 is preferably 3 or more, and the 3 or more cooling medium flows more uniformly due to the design of 3 or more cooling medium water outlets, so that heat dissipation is more uniform, and the lithium target layer 4 is prevented from being melted under the irradiation of particles.

The cooling medium comprises any one of water, liquid nitrogen, amine coolant, cooling oil and polymer coolant.

Barrier layer 3

And the barrier layer 3 is arranged on the substrate layer, and the barrier layer 3 is used for preventing diffusion of lithium in the lithium target layer from escaping from the target layer or preventing diffusion of beryllium in the beryllium target layer from escaping from the target layer.

In this embodiment, a lithium target is preferably used. For lithium targets, irradiation with protons over time results in reduced yield of the protons therein and reduced neutron flux, which directly affects the therapeutic effect of AB-BNCT. The lithium targets currently used for AB-BNCT therefore need to be replaced after a short irradiation time. The shorter lifetime of the lithium target influences the planning of the treatment plan and increases the running cost of the AB-BNCT device. Unfavourable popularization of AB-BNCT therapy. The factor influencing neutron yield is the thickness of the lithium target layer, which can be reduced and uneven during the process of proton bombardment of the lithium target layer, such as sputtering of the lithium target layer under proton bombardment, interdiffusion of the lithium target layer and the substrate layer when the temperature is increased, and the like, and a series of factors reduce the service life of the lithium 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 lithium target layer is melted, and the service life of the lithium target layer is shortened.

The barrier layer is typically selected from materials having a high resistance to lithium diffusion and chemical stability. For example, common materials are metals or alloys, such as tantalum (Ta) or molybdenum (Mo), which have a low diffusion coefficient and a high corrosion resistance. These materials hinder the diffusion of lithium by forming a barrier layer between the lithium target layer and other environment.

The inventor finds that the conventional barrier layer is replaced by rare earth metal oxides such as silicon carbide, aluminum nitride, yttrium oxide, erbium oxide and the like, so that the barrier layer has better effect of preventing the diffusion of lithium. The lithium target is not easy to diffuse at high temperature, so that the integrity of a lithium layer is maintained, and the reduction of the thickness of the lithium film is avoided.

And the thickness of the substrate layer 2 is greater than the thickness of the barrier layer 3; the barrier layer 3 is in contact with the target layer 4; and the barrier layer 3 is arranged to prevent diffusion of the target layer.

The thickness of the substrate layer 2 is set to be larger than that of the barrier layer 3, if the barrier layer 3 is too thick, the transmission path of lithium ions becomes long, the transmission resistance and time can be increased, and the diffusion rate of lithium ions in the target layer can be reduced. In addition, excessively thick barrier layers may create large stress differentials, resulting in structural deformation. If the barrier layer is too thin, sputtering of the lithium target layer due to proton bombardment cannot be avoided, and damage to the lithium target is caused.

To solve this problem, it is further preferable to control the thickness ratio of the substrate layer 2, the barrier layer 3, and the lithium target layer 4 to be as follows by controlling the thickness of the substrate layer 2 to be larger than the thickness of the barrier layer 3: (10-20): 1: (50-300), more preferably 20:1:150.

In another preferred embodiment, both the substrate layer 2 and the barrier layer 3 may be provided as silicon carbide layers. And the thickness of the barrier layer 3 is not easily too thick, preferably less than 5 μm (micrometers), most preferably 1 μm (micrometers).

Target material layer

In the present application, the target layer is preferably a lithium target, but the protective scope thereof is not limited to the lithium target.

Lithium targets are preferred in the present invention because of their lower proton energy requirements for producing the desired neutrons than beryllium targets.

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

In addition, in the utility model, the lithium target layer is prepared by adopting a thermal evaporation deposition mode, and the film prepared by the method often presents tensile stress, and the thermal expansion coefficient of lithium is larger, and the thermal expansion coefficient of the substrate layer is smaller, so that the film can generate thermal stress when the temperature is increased, thereby leading the lithium film to deform, and reducing the service life of the lithium target layer.

In order to solve the technical problem, the inventor of the present application further improves the design, and sets the substrate layer, the lithium-blocking diffusion layer and the lithium target layer to be curved surfaces with consistent curvature radius, and found 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. As shown in fig. 1, the curved surface may be a concave curved surface or a convex curved surface, and in this embodiment, a concave curved surface is preferred, and the sagittal height of the concave curved surface is less than 1 micrometer. Further, preferably, the concave curved surface has a sagittal height of 0.5 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. In another embodiment, the elevation of the concave curve of the lithium target layer 4 is greater than the elevation of the concave curve of the backing layer 2.

As shown in fig. 2, the substrate layer, the lithium-resistant diffusion layer disposed on the substrate layer, and the lithium target layer disposed on the lithium-resistant diffusion layer are of 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 lithium diffusion barrier layer 2 and the protective shell 5 are arranged on the periphery of the lithium target layer 4 in a surrounding manner, and the lithium target layer 4 is coated.

Protective casing 5

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

The protective case 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.

In a preferred embodiment, the thickness ratio of the target layer to the protective structure is (50-250): 1.

The second aspect of the utility model provides an accelerator neutron source, comprising the target structure. Thereby enabling the accelerator neutron source device to have the following effects:

3. By arranging the curved surface type target, deformation of the structural lithium target can be prevented, and the service life of the target structure is further prolonged.

The above list of detailed descriptions is only specific to practical embodiments of the present utility model, and they are not intended to limit the scope of the present utility model, and all equivalent embodiments or modifications that do not depart from the spirit of the present utility model should be included in the scope of the present utility model.

It will be evident to those skilled in the art that the utility model is not limited to the details of the foregoing illustrative embodiments, and that the present utility model may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the utility model being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is provided for clarity only, and that the disclosure is not limited to the embodiments described in detail below, and that the embodiments described in the examples may be combined as appropriate to form other embodiments that will be apparent to those skilled in the art.

Claims

1. A target structure for an accelerator neutron source, the target structure comprising, in order: a substrate layer, a barrier layer, a target layer, and a protective structure;

2. The target structure according to claim 1, wherein a substrate structure is provided on a side of the substrate layer opposite to a side in contact with the barrier layer, and a cooling member is provided inside the substrate structure; the cooling component is used for reducing the temperature of the target layer.

3. The target structure of claim 1, wherein a thickness ratio of the target layer to the protective structure is (50-250): 1.

4. The target structure according to claim 2, wherein the cooling component is an array cooling structure, the array cooling structure comprises a cooling medium, a heat dissipation component for the cooling medium to contact, and a substrate for accommodating the heat dissipation component, and the substrate structure is provided with a liquid inlet and a liquid outlet.

5. The target structure according to claim 4, wherein the cooling medium is any one of water and liquid nitrogen.

6. The target structure according to claim 4, wherein the heat dissipation component is any one of a cylinder, a cuboid, and a cube.

7. The target structure of claim 4, wherein the arrangement of heat dissipating components is an array arrangement and the distance between the heat dissipating components is less than 5 millimeters.

8. The target structure according to claim 1, wherein the substrate layer and the target layer are both arranged in a wafer structure and are arranged in concentric circles.

9. The target structure according to any one of claims 1-8, wherein the target structure is configured as a curved surface, the substrate layer and the target layer are both configured as concave curved surfaces with a uniform radius of curvature, and the sagittal height of the concave curved surfaces is less than 1 micron.

10. An accelerator neutron source comprising a target structure as defined in any one of claims 1 to 9.