Compact vertical rotation high-power neutron target and neutron generation system

Abstract

The invention discloses a compact vertical rotation high-power neutron target and a neutron generation system, and belongs to the field of neutron application. A neutron target body of the neutron target is vertically arranged, a rotating shaft is arranged at the top of the neutron target body, a first connecting pipe and an annular second connecting pipe are arranged in the rotating shaft, the second connecting pipe is located on the periphery of the first connecting pipe, a first cooling sleeve and a second cooling sleeve are annularly arranged in the neutron target body, and the first cooling sleeve is communicated with the first connecting pipe. The second cooling sleeve is communicated with the second connecting pipe, the first cooling sleeve is communicated with the second cooling sleeve, the first connecting pipe, the first cooling sleeve, the second cooling sleeve and the second connecting pipe form a cooling loop, and a cooling working medium is arranged in the cooling loop. An ion source, an isolated gate, an extraction electrode, a low-energy transmission line, an accelerator, a medium-energy transmission line, a compact vertical rotation high-power neutron target, a moderator and a collimator outlet are sequentially arranged in a shell cavity of the neutron generation system, and a reflector is arranged on the inner wall of the shell cavity at a neutron target body.

Description

Technical Field

[0001] This invention belongs to the field of neutron applications, specifically relating to a compact vertical rotating high-power neutron target and a neutron generation system. Background Technology

[0002] Neutrons are crucial particles in nuclear engineering and nuclear technology. They are used in a wide range of scientific research and industrial processes. Neutrons are one of the fundamental particles that make up the atomic nucleus, forming it along with protons. Neutrons play a vital role in nuclear engineering and nuclear technology, primarily in the following areas: maintaining chain reactions in nuclear reactors; conducting activation analysis for materials analysis and environmental monitoring; carrying out scattering research in materials science; using neutrons in breeder reactions in the nuclear fuel cycle; and utilizing neutron sources generated by nuclear reactors and accelerators for scientific, medical, and industrial applications, such as cancer treatment and materials modification. In summary, the efficient, effective, and scientific utilization of neutrons is a key factor in the utilization and safe operation of nuclear energy. Therefore, neutron generation technology is a critical technological link in the field of nuclear engineering and nuclear technology.

[0003] In recent years, with the continuous advancement of high-current linear accelerator technology, high-flux neutron source technology based on high-current linear accelerators has received increasing attention. Compared with high-energy accelerator spallation neutron sources, high-current linear accelerators have advantages such as smaller size, relatively lower cost, lower neutron energy produced, which is more conducive to slowing down into thermal and cold neutrons, and easier protection.

[0004] Miniaturized and compact neutron source technology is attracting increasing attention from researchers due to its wide range of applications. A key component of miniaturized and compact neutron sources is the high-power neutron target, which is crucial for the acquisition of high-quality beams. Due to the excitation ionization process and energy loss deposition during nuclear reactions, such targets need to withstand very high thermal loads and are commonly referred to as high-power neutron targets.

[0005] The renowned Jülich Neutron Science Center in Germany is developing a high-brightness neutron source, HBS, based on a high-current linear accelerator. This device aims to use a linear accelerator to accelerate pulsed proton or deuterium beams to 50 MeV or 100 MeV to bombard a high-power neutron target, producing neutrons. The maximum beam power on the target is 100 kW, and the irradiated area is 100 cm². 2 This corresponds to a heat flux density of up to 10 MW / m³. 2 At levels above 1000 ohms. Under such high heat flux density conditions, ensuring effective cooling of the high-power neutron target is crucial, while a compact design allows for miniaturization of the equipment.

[0006] Therefore, under the requirements of miniaturization and compactness of neutron source technology or neutron generation systems, there is an urgent need for high-power neutron targets and neutron generation systems that can effectively generate the required neutrons and withstand high heat flux densities. Summary of the Invention

[0007] The purpose of this invention is to provide a compact vertical rotating high-power neutron target to meet the miniaturization and compactness requirements of neutron source technology or neutron generation systems. Through innovative target material cooling and structural design, the thermal management problem of the target material under high-power proton beam bombardment is effectively solved, significantly improving system life and stability, while realizing the compactness of the device.

[0008] Another object of the present invention is to provide a neutron generation system comprising the above-described compact vertical rotating high-power neutron target.

[0009] The technical solution of this invention is: (i) A compact vertical rotating high-power neutron target, comprising a neutron target body, the neutron target body being vertically arranged, a rotating shaft being provided at the top of the neutron target body, the rotating shaft being driven and connected to a shielded motor; a first connecting pipe and an annular second connecting pipe are provided inside the rotating shaft, the second connecting pipe being located outside the first connecting pipe, a first cooling sleeve and a second cooling sleeve being provided circumferentially inside the neutron target body, the first cooling sleeve being connected to the first connecting pipe, the second cooling sleeve being connected to the second connecting pipe, the bottom of the first cooling sleeve and the bottom of the second cooling sleeve being connected, the first connecting pipe, the first cooling sleeve, the second cooling sleeve and the second connecting pipe forming a cooling circuit, the cooling circuit being provided with a cooling working fluid.

[0010] As a further improvement of the present invention, the output end of the shielded motor is provided with an active pulley, a passive pulley is connected to the rotating shaft, and a transmission belt is connected between the active pulley and the passive pulley.

[0011] As a further improvement of the present invention, liquid gallium is used as the cooling medium.

[0012] As a further improvement of the present invention, the neutron target body is composed of a copper substrate and a coating on its surface, and an air cavity is provided in the center of the copper substrate.

[0013] (ii) A neutron generation system, comprising an outer shell cavity, wherein an ion source, an isolation grid, an extraction electrode, a low-energy transmission line, an accelerator, a medium-energy transmission line, a compact vertical rotating high-power neutron target, and a moderator are sequentially arranged inside the outer shell cavity, a collimator outlet is provided at the end of the outer shell cavity, the moderator is located at the collimator outlet, and a reflector is provided on the inner wall of the outer shell cavity at the neutron target body.

[0014] Furthermore, the shielded motor is located outside the housing cavity.

[0015] The beneficial effects of this invention are: 1. This invention proposes a compact vertically rotating high-power neutron target, employing a vertical rotation design. The vertical rotation design significantly shortens the average irradiation / heating time of the irradiated / heated surface of the high-power neutron target, increasing heat exchange capacity and improving the working capability of the high-power neutron target compared to a fixed target design. Furthermore, the vertical rotation design reduces the volume of the high-power neutron target compared to a planar rotation design.

[0016] 2. The high-power neutron target of this invention is entirely covered by a first cooling jacket and a second cooling jacket, providing cyclic cooling for the neutron target body. Using liquid gallium as the cooling medium for the high-power neutron target offers several advantages. Liquid gallium has better heat transfer capabilities, especially in the supercooled boiling range, where its heat transfer coefficient is greater than that of supercooled water. Furthermore, liquid gallium is physically stable, has a wide operating range, and is not easily activated, making it suitable for cooling operations requiring higher heat transfer capabilities. Using liquid gallium enhances the heat transfer capacity of the high-power target, reduces the size of the high-power target system, and is highly beneficial for the miniaturization and compactness of neutron generation systems.

[0017] 3. The neutron generation system of this invention employs a vertically rotating high-power neutron target, with the rotary joint located outside the neutron generation system, thus improving system reliability. This neutron generation system can stably output a high-quality neutron beam. While possessing safety and high efficiency, it also allows for miniaturization and compactness of the equipment, greatly expanding the application range of neutron generation systems or neutron sources in space-constrained scenarios. The miniaturized and compact design of this invention also reduces manufacturing costs, facilitating the widespread use of such equipment. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a compact vertical rotating high-power neutron target according to the present invention; Figure 2 This is a cross-sectional view of the neutron target body in this invention; Figure 3 This is a schematic diagram of the structure of a neutron generation system according to the present invention.

[0019] In the figure, 1-ion source; 2-isolation grid; 3-extraction electrode; 4-low energy transmission line; 5-accelerator; 6-medium energy transmission line; 8-neutron target body; 81-copper substrate; 82-coating; 83-air cavity; 9-reflector; 10-moderator; 12-first connecting pipe; 121-first cooling jacket; 13-second connecting pipe; 131-second cooling jacket; 14-outer shell cavity; 15-collimator outlet; 16-shielded motor; 17-rotating shaft; 18-drive pulley; 19-transmission belt; 20-passive pulley. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 1 , Figure 2 As shown, a compact vertically rotating high-power neutron target includes a neutron target body 8, which is vertically arranged. A rotating shaft 17 is located at the top of the neutron target body 8, and a shielded motor 16 is connected to the rotating shaft 17. A first connecting pipe 12 and an annular second connecting pipe 13 are located inside the rotating shaft 17, with the second connecting pipe 13 located outside the first connecting pipe 12. The rotating shaft 17, the first connecting pipe 12, and the second connecting pipe 13 are coaxially arranged. A first cooling sleeve 121 and a second cooling sleeve 131 are arranged circumferentially inside the neutron target body 8, with the second cooling sleeve 131 located outside the second cooling sleeve 121. The first cooling sleeve 121 communicates with the first connecting pipe 12, and the second cooling sleeve 131 communicates with the second connecting pipe 13. The bottoms of the first cooling sleeve 121 and the second cooling sleeve 131 are connected. The first connecting pipe 12, the first cooling sleeve 121, the second cooling sleeve 131, and the second connecting pipe 13 form a cooling circuit, within which a cooling medium is provided. The cooling medium is liquid gallium.

[0022] The output end of the shielded motor 16 is provided with a drive pulley 18, and a driven pulley 20 is connected to the shaft 17. A transmission belt 19 is connected between the drive pulley 18 and the driven pulley 20.

[0023] The neutron target body 8 consists of a copper substrate 81 and a coating 82 on its surface. An air cavity 83 is formed in the center of the copper substrate 81. The copper substrate 81 serves as the core structural support and main heat-conducting component of the target. The coating 82, plated or bonded to the copper substrate 81, is the region where the proton beam bombardment causes nuclear reactions to produce neutrons. The air cavity 83, located inside the copper substrate 81 and filled with air, is used to optimize the neutron output energy spectrum and reduce neutron loss.

[0024] like Figure 3 As shown, a neutron generation system includes an outer shell cavity 14. Inside the outer shell cavity 14, an ion source 1, an isolation grid 2, an extraction electrode 3, a low-energy transmission line 4, an accelerator 5, a medium-energy transmission line 6, a compact vertical rotating high-power neutron target, and a moderator 10 are arranged sequentially. A collimator outlet 15 is provided at the end of the outer shell cavity 14, and the moderator 10 is located at the collimator outlet 15. A reflector 9 is provided on the inner wall of the outer shell cavity 14 at the neutron target body 8.

[0025] The shielded motor 16 is located outside the housing cavity 14.

[0026] Ion source 1 is used to ionize hydrogen atoms to produce high-energy protons. Ion source 1 is preferably an ECR ion source. ECR ion source systems have advantages such as compact structure, long lifespan, high beam intensity, high beam quality, stable and reliable operation, and convenient maintenance. Its working principle is to use electromagnetic and microwave fields to heat and excite electrons, increasing their energy to form a high-energy electron beam; these high-energy electrons collide with the introduced hydrogen atoms, ionizing them. The ionization process follows the equations below: .

[0027] The isolation barrier 2 is used to precisely filter out the desired proton beam from the particle swarm.

[0028] The function of the extraction electrode 3 is to extract the signal from the device for amplification or other purposes. In this invention, the extraction electrode 3 introduces the proton beam into the low-energy transmission line 4. The extraction electrode 3 initially extracts the proton beam, forming the initial proton beam.

[0029] The proton beam generated by ion source 1 is a high-energy beam and cannot be directly accelerated by accelerator 5. Low-energy transmission line 4 performs preliminary focusing and matching on the extracted proton beam, that is, adjusts the energy of the high-energy proton beam to make it suitable for acceleration by accelerator 5.

[0030] Accelerator 5 is used to accelerate the proton beam to a predetermined energy. Accelerator 5 is preferably an RFQ accelerator. The principle of proton acceleration by the RFQ accelerator is based on radio frequency quadrupole (RFQ) technology, which simultaneously achieves lateral focusing and longitudinal beam convergence and acceleration of the proton beam by applying a high-frequency electric field, thereby enabling efficient beam transmission and acceleration.

[0031] The main function of medium-energy transmission line 6 is to perform beam matching on the high-energy proton beam before it strikes the target, ensuring it is ready for impact. Medium-energy transmission line 6 precisely transmits the accelerated proton beam to the target's impact region.

[0032] The high-power neutron target is a component used to generate neutrons. The preferred rotational speed of the neutron target body 8 is 300-600 revolutions per minute. The rotational motion of the neutron target body 8 causes the bombardment point of the proton beam to move continuously on the target surface, avoiding local overheating and significantly improving the target's ability to withstand high thermal loads.

[0033] Coating 82 is preferably a lithium coating (e.g.) 7 Li), the accelerated proton beam bombards the lithium coating, through 7 Li(p,n) 7 Be nuclei reactions produce neutron beams.

[0034] The reflector 9 surrounds the neutron target body 8 and is used to reflect the diverging neutrons in a predetermined direction.

[0035] The moderator 10 is used to slow down and homogenize the neutron beam generated by the nuclear reaction, slowing down the generated high-energy fast neutrons to the required energy so that they can be extracted from the collimator outlet 15. The main material of the moderator 10 is preferably a mixture of magnesium fluoride (MgF2), lithium fluoride (LiF), and aluminum (Al). These materials have a high scattering cross section for neutrons, and the neutrons collide with the atomic nuclei multiple times inside the moderator, effectively reducing their energy and thus achieving the purpose of slowing down the neutrons.

[0036] The collimator outlet 15 is used to collimate and shape the slowed neutron beam before outputting it.

[0037] The first connecting pipe 12 and the second connecting pipe 13 are connected to an external liquid gallium circulation supply system via a rotary joint (not shown in the figure, which is a conventional technology in the field), thereby realizing continuous and sealed delivery of coolant in a rotating state.

[0038] Hydrogen atoms are ionized in ion source 1 to generate a high-energy proton beam. The desired proton beam is filtered by isolation grid 2 and extracted and focused by extraction electrode 3 and low-energy transmission line 4. The proton beam is accelerated by accelerator 5 and bombarded with neutron target body 8 through medium-energy transmission line 6. Neutron target body 8 is rotated counterclockwise along its central axis by shielded motor 16. The proton beam generates a nuclear reaction on the coating 82 on the surface of neutron target body 8, producing a neutron beam. The generated neutron beam is reflected by reflector 9 and slowed down by moderator 10 to form a neutron beam with the desired energy spectrum. Finally, it is extracted by collimator outlet 15 and can be used in neutron radiography, material activation analysis, boron neutron capture therapy (BNCT), and other fields. Throughout the process, the heat of the target body is efficiently removed by continuously circulating liquid gallium, ensuring the long-term stable operation of the system.

[0039] The proton beam undergoes a nuclear reaction on the coating 82 on the surface of the neutron target 8, producing neutrons. This nuclear reaction generates a large amount of heat, resulting in an extremely high heat flux density. The deposited heat is rapidly transferred to the copper substrate 81 via the coating 82 on the surface of the neutron target 8. The copper substrate 81 is then cooled in a single-phase manner through forced circulation using a cooling medium. Liquid gallium enters the first cooling jacket 121 (or the second cooling jacket 131) from the top of the neutron target 8 through the first connecting pipe 12 (or the second connecting pipe 13), then flows back through the second cooling jacket 131 (or the first cooling jacket 121) and exits through the second connecting pipe 13 (or the first cooling jacket 121), efficiently carrying away heat. Simultaneously, the shielded motor 16 drives the neutron target 8 to rotate continuously counterclockwise around the axis 17, ensuring that no area on the surface of the neutron target 8 is continuously irradiated by the proton beam. This disperses the instantaneous high heat load in time and space, greatly improving the target material's tolerance limit and lifespan.

[0040] The vertical rotation design of the neutron target body 8 ensures that its surface is not continuously irradiated by the proton beam, thus reducing the average heating time and improving heat transfer capacity. This design also allows for a reduction in the volume of high-power targets. Liquid gallium (GaN) offers superior heat transfer capabilities, particularly in the supercooled boiling range, where its heat transfer coefficient is greater than that of supercooled water. Liquid gallium is physically stable, with a melting point of only 29.76°C, and while it may be liquid at room temperature, its boiling point is as high as 2403°C. Furthermore, liquid gallium has a wide operating range and is less prone to activation, making it suitable for cooling operations with higher heat transfer capabilities. Using liquid gallium enhances the heat transfer capacity of the neutron target body 8 while requiring less working fluid, facilitating the miniaturization of high-power neutron target designs. The vertical rotation design of the neutron target body 8, combined with the liquid gallium cooling circuit, improves its thermal tolerance limit and operational capability, facilitating the miniaturization of both the neutron target body 8 and the neutron generation system.

[0041] Key innovative designs and advantages of this invention: 1. Application of Liquid Gallium Coolant: This invention selects liquid metallic gallium as the cooling medium. It possesses excellent thermophysical properties such as low melting point, high boiling point, large heat capacity, and high thermal conductivity, and is chemically stable and not easily activated. Its overall heat exchange performance is far superior to conventional water cooling solutions. This allows for a smaller coolant flow rate to remove the same amount of heat, reducing system piping and pumping power, directly promoting system compactness and miniaturization.

[0042] 2. Vertical Rotating Target Structure: The rotating design ensures that the beam heat load is no longer concentrated in a fixed area, but is evenly distributed across a ring. Combined with the high-efficiency heat exchange of liquid gallium, this fundamentally solves the problems of target material ablation and short lifespan caused by high heat flux density. The vertical arrangement also facilitates the realization of rotary sealing and the overall integration of the system.

[0043] 3. Compact Integrated Design: The two core innovations mentioned above, combined with the optimized arrangement of components such as reflectors and moderators, enable the entire neutron generation system to achieve a compact structure and miniaturized size while ensuring high performance and high reliability, making it suitable for deployment and application in space-constrained environments such as hospitals and laboratories.

Claims

1. A compact vertically rotating high-power neutron target, comprising a neutron target body (8), characterized in that: The neutron target body (8) is vertically arranged, and a rotating shaft (17) is provided at the top of the neutron target body (8). The rotating shaft (17) is connected to a shielded motor (16). A first connecting pipe (12) and an annular second connecting pipe (13) are provided inside the rotating shaft (17). The second connecting pipe (13) is located outside the first connecting pipe (12). A first cooling sleeve (121) and a second cooling sleeve (131) are provided circumferentially inside the neutron target body (8). The first cooling sleeve (121) is connected to the first connecting pipe (12), and the second cooling sleeve (131) is connected to the second connecting pipe (13). The bottom of the first cooling sleeve (121) and the bottom of the second cooling sleeve (131) are connected. The first connecting pipe (12), the first cooling sleeve (121), the second cooling sleeve (131), and the second connecting pipe (13) constitute a cooling circuit. A cooling working medium is provided in the cooling circuit.

2. The compact vertical rotating high-power neutron target according to claim 1, characterized in that: The output end of the shielded motor (16) is provided with an active pulley (18), and a passive pulley (20) is connected to the rotating shaft (17). A transmission belt (19) is connected between the active pulley (18) and the passive pulley (20).

3. A compact vertical rotating high-power neutron target according to claim 1 or 2, characterized in that: The cooling medium is liquid gallium.

4. A compact vertical rotating high-power neutron target according to claim 3, characterized in that: The neutron target body (8) consists of a copper substrate (81) and a coating (82) on its surface, with an air cavity (83) at the center of the copper substrate (81).

5. A neutron generation system, comprising a shell cavity (14), characterized in that: The outer shell cavity (14) is provided with an ion source (1), an isolation grid (2), an extraction electrode (3), a low-energy transmission line (4), an accelerator (5), a medium-energy transmission line (6), a compact vertical rotating high-power neutron target as described in any one of claims 1-4, and a moderator (10). The outer shell cavity (14) is provided with a collimator outlet (15) at its end. The moderator (10) is located at the collimator outlet (15). The inner wall of the outer shell cavity (14) at the neutron target body (8) is provided with a reflector (9).

6. A neutron generation system according to claim 5, characterized in that: The shielded motor (16) is located outside the outer shell cavity (14).

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