Neutron conversion target and accelerator system having the same

Abstract

The utility model discloses a kind of neutron conversion target and accelerator system with it, neutron conversion target includes: target matrix, target matrix is defined with target cavity extending along its axial direction inside, target cavity has open end and closed end, the inner surface of target cavity periphery is formed as first target face, the inner surface of target cavity closed end is formed as second target face, incident beam current is incident target cavity through open end, the neutron beam produced after incident beam current bombardment first target face and second target face is emitted through second target face;Cooling channel, set in target matrix, and with target cavity is associated with arrangement to be used to cool it;Cooling medium, flow through cooling channel, to cool first target face and second target face.The neutron conversion target according to the utility model embodiment, by setting second target face around first target face, when target matrix receives incident beam current bombardment, both can guarantee that the temperature of target matrix is within safe range, prolong the service life of neutron conversion target, and can improve the flux density of beam direction neutron.

Description

Technical Field

[0001] This utility model belongs to the field of accelerator technology, specifically relating to a neutron conversion target and an accelerator system having the same. Background Technology

[0002] BNCT is a technique that uses neutrons to treat tumors. A proton accelerator accelerates protons or deuterium ions to a certain energy (above 2.5 MeV) and then bombards a lithium target. The performance of the target determines the neutron conversion efficiency, energy spectrum, and the power it can withstand.

[0003] Currently, proton accelerators use fixed planar targets for neutron conversion. To increase the proton power that can be handled, the cross-sectional area of ​​the proton beam can be appropriately increased, dispersing the proton beam power over a larger target surface, thereby reducing power density and improving heat dissipation. For low-melting-point lithium targets (180℃), when the proton beam power is further increased to tens of kilowatts, such as 50-80kW, the size of the proton beam spot is constrained (the diameter is generally less than 6cm to facilitate neutron utilization). Even with a rotating target and good cooling performance, the target surface temperature will rise sharply due to the large instantaneous temperature rise at the proton bombardment site, leading to the evaporation and depletion of lithium.

[0004] To reduce target surface temperature, rotating planar targets are used to distribute ion power over a larger area. However, rotating targets have complex structures, which greatly limits heat dissipation from the target substrate, and the heat dissipation rate and lifespan of the bearings are technical bottlenecks. While novel heat dissipation methods such as phase change cooling promise to significantly reduce target surface temperature, the technical challenges of achieving vacuum and insulation are substantial. Furthermore, because the concentration of neutrons in the proton beam direction is not high, the utilization rate of neutrons using existing planar targets is not high, which is detrimental to reducing the time required for applications such as neutron therapy. Utility Model Content

[0005] The purpose of this utility model embodiment is to provide a neutron conversion target and an accelerator system having the same, so as to solve the problem in the prior art that when the output power of the proton accelerator is high and the beam power density is too large, the lithium conversion target will have an instantaneous high temperature and low forward neutron flux density when bombarded by protons.

[0006] A first aspect of this utility model provides a neutron conversion target for being bombarded by an incident beam to generate a neutron beam, the neutron conversion target comprising: A target substrate, wherein a target cavity extending along its axial direction is defined within the target substrate, the target cavity having an open end and a closed end, the inner surface of the target cavity in the circumferential direction being formed as a first target surface, and the inner surface of the closed end of the target cavity being formed as a second target surface, the incident beam entering the target cavity through the open end, and the neutron beam generated after the incident beam bombards the first target surface and the second target surface being emitted through the second target surface; A cooling channel is disposed within the target substrate and associated with the target cavity for cooling the target. Cooling medium flows through the cooling channel to cool the first target surface and the second target surface.

[0007] Furthermore, the target substrate includes: The first target assembly includes a plurality of coaxially arranged conical cylinders, the radial dimension of which gradually increases from the open end to the closed end along the axial direction of the target cavity, and the inner surface of the conical cylinder facing the target cavity is formed as the first target surface; The second target assembly is formed as a plate-like structure and is disposed at the larger end of the first target assembly, and together with the first target assembly, defines the target cavity. The inner surface of the second target assembly facing the target cavity is formed as the second target surface.

[0008] Further, the first target component includes: The reflective layer is a plurality of coaxially spaced conical cylinders, and the cooling channel is provided inside the reflective layer; A target layer is coated on the inner wall surface of the reflective layer facing the target cavity to form the first target surface.

[0009] Furthermore, the second target component includes: A heat-conducting component, wherein the heat-conducting component is formed in a plate-like structure; A target layer is coated on the inner wall surface of the heat-conducting element facing the target cavity to form the second target surface.

[0010] Furthermore, the target substrate includes: A first target assembly includes a plurality of coaxially arranged annular members, each annular member having an equal inner diameter, and the inner surface of each annular member being formed as the first target surface. The second target assembly is a plate-shaped structure disposed at one end of the first target assembly and together with the first target assembly defines the target cavity. The inner surface of the second target assembly facing the target cavity is formed as the second target surface.

[0011] Furthermore, the target substrate also includes: The third target assembly is formed as an annular member with an inner diameter smaller than that of the first target assembly. The third target assembly is disposed between the first target assembly and the second target assembly to define a target cavity together with the first target assembly and the second target assembly. The surface of the third target assembly facing the target cavity is formed as the first target surface.

[0012] Further, the first target component and the third target component each include: A heat-conducting component, wherein the heat-conducting component is formed as a ring and a cooling channel is defined within the heat-conducting component; A reflective layer is coated on the inner wall surface of the heat-conducting component facing the target cavity; A target layer, which is coated on the reflective layer to form the first target surface.

[0013] Furthermore, the second target component includes: A heat-conducting component, wherein the heat-conducting component is formed in a plate-like structure; A target layer is coated on the inner wall surface of the heat-conducting element facing the target cavity to form the second target surface.

[0014] Furthermore, the reflective layer is made of beryllium oxide; and / or the target layer is made of lithium.

[0015] A second aspect of this utility model provides an accelerator system, comprising: A focusing assembly for focusing an incident beam; The neutron conversion target described in the above embodiments.

[0016] According to the neutron conversion target of this utility model embodiment, by setting a second target surface around the first target surface, when the target substrate receives the incident beam bombardment, it can ensure that the temperature of the target substrate is within a safe range, extend the service life of the neutron conversion target, and increase the neutron flux density in the beam direction. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a neutron conversion target in the prior art; Figure 2 This is a schematic diagram of the structure of a conversion target according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of another neutron conversion target according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a target component of a neutron conversion target according to an embodiment of the present invention.

[0018] Figure Labels

[0019] Neutron conversion target 100; moderator 200; Target substrate 10; first target surface 11; second target surface 12; first target assembly 13; second target assembly 14; third target assembly 15; Cooling channel 20; Cooling medium 30; Incident beam 1; neutron beam 2; target cavity A; heat-conducting component B; reflective layer C; target layer D. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model.

[0021] The terms "first," "second," etc., used in the specification and claims of this utility model are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this utility model can be implemented in orders other than those illustrated or described herein. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0022] The following is combined Figures 1 to 4 The neutron conversion target 100 provided in this utility model embodiment will be described in detail through specific embodiments and application scenarios.

[0023] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0024] The neutron conversion target 100 according to an embodiment of the present invention mainly includes a target substrate 10, a cooling channel 20, and a cooling medium 30. Specifically, the neutron conversion target 100 is used to be bombarded by an incident beam 1 to generate a neutron beam 2. The neutron conversion target 100 includes a target substrate 10, within which a target cavity A extending axially is defined. The target cavity A has an open end and a closed end. The inner surface of the target cavity A in the circumferential direction is formed as a first target surface 11, and the inner surface of the closed end of the target cavity A is formed as a second target surface 12. The incident beam 1 enters the target cavity A through the open end. The neutron beam 2 generated after the incident beam 1 bombards the first target surface 11 and the second target surface 12 is emitted through the second target surface 12. The cooling channel 20 is disposed within the target substrate 10 and associated with the target cavity A for cooling it. The cooling medium 30 flows through the cooling channel 20 to cool the first target surface 11 and the second target surface 12.

[0025] Specifically, Figure 1The traditional planar target structure 300 suffers from excessive power density at a given beam size, leading to severe target material evaporation and consumption. The neutron conversion target 100 according to this embodiment is equivalent to adding a three-dimensional second target surface 12 around the traditional planar target (first target surface 11), forming a cavity-like target cavity A. At the end of target cavity A, a planar target is still used, fully utilizing the ions or protons at the beam center. The incident beam 1 (ion beam or proton beam) is strongly focused to form a beam with a large divergence angle. This ion beam bombards the first target surface 11 and the second target surface 12, thereby increasing the contact area between the incident beam 1 and the target surface, increasing heat dissipation, and reducing the transient power density at the ion beam or proton beam deposition location. Both the neutron beam 2 reflected from the first target surface 11 and the neutron beam 2 transmitted from the second target surface 12 by the incident beam 1 are effectively utilized, improving the neutron production rate. In addition, by setting a cooling channel 20 inside the target substrate 10, the cooling medium 30 circulates in the cooling channel 20, resulting in better cooling effect, reducing the problem of excessively high instantaneous temperature of the target when bombarded by the incident beam 1, and greatly improving the effective cooling power.

[0026] Therefore, according to the embodiment of the present invention, the neutron conversion target 100, by setting a second target surface 12 around the first target surface 11, can ensure that the temperature of the target substrate 10 is within a safe range when the target substrate 10 is bombarded by the incident beam 1, thus extending the service life of the neutron conversion target 100, and also increasing the neutron flux density in the beam direction.

[0027] According to one embodiment of the present invention, the target substrate 10 includes a first target component 13 and a second target component 14.

[0028] The first target assembly 13 includes a plurality of coaxially arranged conical cylinders. The radial dimension of the conical cylinders gradually increases from the open end to the closed end along the axial direction of the target cavity A. The inner surface of the conical cylinder facing the target cavity A is formed as a first target surface 11. The second target assembly 14 is formed as a plate structure, disposed at the larger end of the first target assembly 13, and together with the first target assembly 13, defines the target cavity A. The inner surface of the second target assembly 14 facing the target cavity A is formed as a second target surface 12.

[0029] like Figure 2 As shown, the first target assembly 13 is similar to multiple horn-shaped conical tubes. These conical tubes are spaced apart on the incident axis of the incident beam 1, and the openings of the conical tubes expand downstream of the incident beam 1. Compared with the planar target, the heat dissipation boundary of the multilayer target is significantly increased, and the flux of the cooling medium 30 is correspondingly increased. This arrangement not only increases the surface area of ​​the first target surface 11 and improves the deposition area of ​​actual ions or protons, but also facilitates heat dissipation, which is beneficial to improving the effective cooling power and reducing the transient power density of the ion beam or proton beam.

[0030] Furthermore, the first target component 13 includes a reflective layer C and a target layer D.

[0031] The reflective layer C consists of multiple coaxially spaced conical cylinders, and a cooling channel 20 is provided inside the reflective layer C; the target layer D is coated on the inner wall surface of the reflective layer C facing the target cavity A to form the first target surface 11.

[0032] like Figure 2 As shown, the first target assembly 13 mainly consists of a reflective layer C and a target layer D. The reflective layer C uses a material with high reflectivity as the matrix material of the cooling target. Compared with the planar cooling target, the cavity-shaped reflective target of this utility model embodiment can significantly improve the forward neutron flux density.

[0033] Preferably, the second target assembly 14 includes a heat-conducting element B and a target layer D.

[0034] Specifically, the heat-conducting component B is formed as a plate-like structure, and a cooling channel 20 is defined within the heat-conducting component B. The cooling medium 30 flows through the cooling channel 20 to dissipate heat from the heat-conducting component B. The target layer D is coated on the inner wall surface of the heat-conducting component B facing the target cavity A to form a second target surface 12. The second target surface 12 is bombarded by the incident beam 1 and then emits a neutron beam 2. According to one embodiment of the present invention, the target substrate 10 includes a first target assembly 13 and a second target assembly 14.

[0035] Specifically, such as Figure 3 As shown, the first target assembly 13 includes a plurality of coaxially arranged annular members with equal inner diameters, and the inner surface of the annular members is formed as a first target surface 11; the second target assembly 14 is a plate-shaped structure, disposed at one end of the first target assembly 13, and together with the first target assembly 13, defines a target cavity A, and the inner surface of the second target assembly 14 facing the target cavity A is formed as a second target surface 12.

[0036] like Figure 3 As shown, target cavity A is essentially a cylindrical cavity. The first target assembly 13 is not integrally formed but is composed of multiple annular components. This structure facilitates the fabrication of the cooling channel 20. After the incident beam 1 is strongly focused, it forms a large divergence angle, which is beneficial for its gradual divergence and deposition on the inner wall of the long cylindrical cavity. After being bombarded by the incident beam 1, the first target surface 11 can reflect the neutron beam 2, and the second target surface 12 can transmit the neutron beam 2.

[0037] Furthermore, the target substrate 10 also includes a third target component 15, which is formed as an annular member with an inner diameter smaller than that of the first target component 13. The third target component 15 is disposed between the first target component 13 and the second target component 14 to define the target cavity A together with the first target component 13 and the second target component 14. The surface of the third target component 15 facing the target cavity A is formed as a first target surface 11.

[0038] like Figure 3 As shown, the third target assembly 15 forms a stepped structure with the first target assembly 13 and the second target assembly 14. In addition, multiple similar structures can be set between the first target assembly 13 and the second target assembly 14. Since the incident beam 1 has a high intensity in the middle, the use of a multi-level stepped structure can further disperse the power density.

[0039] Taking a cylindrical target cavity A as an example, such as Figure 3 As shown, the ion deposition area ratio Ks (i.e., the ratio of the actual ion beam deposition area to the ion beam cross-street area) is: Ks = 4L / D + 1. When L / D > 25, the power density and heat dissipation boundary of the target surface are reduced by more than two orders of magnitude compared to a planar target surface. For a proton beam with a beam spot size of approximately 6 cm, a target cavity length of 1.5 m is highly feasible.

[0040] Preferably, the first target assembly 13 and the third target assembly 15 respectively include a heat-conducting element B, a reflective layer C, and a target layer D.

[0041] Specifically, such as Figure 3 As shown, the heat-conducting component B is formed as a ring, and a cooling channel 20 is defined within the heat-conducting component B, such as... Figure 4 As shown, the cooling channel 20 can also be annular; the reflective layer C is coated on the inner wall surface of the heat-conducting component B facing the target cavity A; the target layer D is coated on the reflective layer C to form the first target surface 11.

[0042] In another embodiment of the present invention, the second target assembly 14 includes a heat-conducting element B and a target layer D. Specifically, the heat-conducting element B is formed into a plate-like structure; the target layer D is coated on the inner wall surface of the heat-conducting element B facing the target cavity A to form a second target surface 12.

[0043] Preferably, the reflective layer C is made of beryllium oxide. To improve both heat dissipation and neutron utilization, beryllium oxide and other materials with high neutron reflectivity are used as the substrate material for the cavity-shaped cooling target. Compared to a planar cooling target, reflection from the cavity wall can significantly increase the forward-emitted neutron flux density. Optionally, the target layer D is made of lithium.

[0044] The accelerator system according to the second aspect of the present invention includes: a focusing component (not shown) and a neutron conversion target 100 as described in the above embodiment. The focusing component applies strong focusing to the incident beam 1, so that it is over-focused to form a particle beam with a large divergence angle, which is beneficial for the beam to be gradually deposited on the target surface of the inner wall of the target cavity A. The neutron beam 2 bombarded by the beam is used after being shaped by the moderator 200.

[0045] Since the neutron conversion target 100 according to the present invention has the advantages of long service life and high neutron flux density, and the accelerator system according to the present invention has the neutron conversion target 100 described in the above embodiments, the accelerator system according to the present invention also has the above advantages.

[0046] Other structures and techniques of the accelerator system according to the embodiments of this utility model are prior art and will not be described in detail here.

[0047] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A neutron conversion target, used to be bombarded by an incident beam to generate a neutron beam, characterized in that, The neutron conversion target includes: A target substrate, wherein a target cavity extending along its axial direction is defined within the target substrate, the target cavity having an open end and a closed end, the inner surface of the target cavity in the circumferential direction being formed as a first target surface, and the inner surface of the closed end of the target cavity being formed as a second target surface, the incident beam entering the target cavity through the open end, and the neutron beam generated after the incident beam bombards the first target surface and the second target surface being emitted through the second target surface; A cooling channel is disposed within the target substrate and associated with the target cavity for cooling the target. Cooling medium flows through the cooling channel to cool the first target surface and the second target surface.

2. The neutron conversion target according to claim 1, characterized in that, The target matrix includes: The first target assembly includes a plurality of coaxially arranged conical cylinders, the radial dimension of which gradually increases from the open end to the closed end along the axial direction of the target cavity, and the inner surface of the conical cylinder facing the target cavity is formed as the first target surface; The second target assembly is formed as a plate-like structure and is disposed at the larger end of the first target assembly, and together with the first target assembly, defines the target cavity. The inner surface of the second target assembly facing the target cavity is formed as the second target surface.

3. The neutron conversion target according to claim 2, characterized in that, The first target component includes: The reflective layer is a plurality of coaxially spaced conical cylinders, and the cooling channel is provided inside the reflective layer; A target layer is coated on the inner wall surface of the reflective layer facing the target cavity to form the first target surface.

4. The neutron conversion target according to claim 2, characterized in that, The second target component includes: A heat-conducting component, wherein the heat-conducting component is formed in a plate-like structure; A target layer is coated on the inner wall surface of the heat-conducting element facing the target cavity to form the second target surface.

5. The neutron conversion target according to claim 1, characterized in that, The target matrix includes: A first target assembly includes a plurality of coaxially arranged annular members, each annular member having an equal inner diameter, and the inner surface of each annular member being formed as the first target surface. The second target assembly is a plate-shaped structure disposed at one end of the first target assembly and together with the first target assembly defines the target cavity. The inner surface of the second target assembly facing the target cavity is formed as the second target surface.

6. The neutron conversion target according to claim 5, characterized in that, The target matrix also includes: The third target assembly is formed as an annular member with an inner diameter smaller than that of the first target assembly. The third target assembly is disposed between the first target assembly and the second target assembly to define a target cavity together with the first target assembly and the second target assembly. The surface of the third target assembly facing the target cavity is formed as the first target surface.

7. The neutron conversion target according to claim 6, characterized in that, The first target assembly and the third target assembly each include: A heat-conducting component, wherein the heat-conducting component is formed as a ring and a cooling channel is defined within the heat-conducting component; A reflective layer is coated on the inner wall surface of the heat-conducting component facing the target cavity; A target layer, which is coated on the reflective layer to form the first target surface.

8. The neutron conversion target according to claim 5 or 6, characterized in that, The second target component includes: A heat-conducting component, wherein the heat-conducting component is formed in a plate-like structure; A target layer is coated on the inner wall surface of the heat-conducting element facing the target cavity to form the second target surface.

9. The neutron conversion target according to claim 3 or 7, characterized in that, The reflective layer is made of beryllium oxide; and / or the target layer is made of lithium.

10. An accelerator system, characterized in that, include: A focusing assembly for focusing an incident beam; The neutron conversion target according to any one of claims 1-9.

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