Small high heat flux density nuclear reaction target

Abstract

The present application relates to a kind of small high heat flux nuclear reaction target, reaction target is arranged in the water circuit of pipeline end, water circuit includes the water inlet pipe and water outlet pipe being arranged in the two sides of pipeline end, and the heat dissipation pipe being arranged between water inlet pipe and water outlet pipe, heat dissipation pipe is enclosed by reaction target and cover plate, the two sides of reaction target are connected with water inlet pipe end and water outlet pipe entrance respectively, micro-groove structure is arranged in the back of reaction target. Good heat conduction performance of red copper plate is used as reaction target, the actual parameter of micro-groove is determined according to thermodynamic simulation parameter, and the heat dissipation effect of reaction target is optimized. Cover plate uses organic glass material with smaller gamma ray absorption. Using the nuclear reaction target disclosed in the present application, more than 5kW / cm 2 Heat flux can be efficiently dissipated, and when using the cylindrical detector, the target can be easily replaced, and the reaction target is small enough to have little effect on gamma detection efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of nuclear reaction targets, and particularly relates to a small high-heat-flux nuclear reaction target. BACKGROUND

[0002] The world's strongest current, the 400kV strong current accelerator in the Jinping deep underground laboratory, can provide a 10mA proton beam or a 5mA He+ beam, and the beam spot size is about 10mm in diameter (±2σ). The total power of the 10mA energy 100keV proton beam is 1kW, and the heat flux density is as shown in the following table: Figure 1 As can be seen from the table, the central heat flux density can reach 2.5kW / cm 2 . For the strong current experiment carried out on the accelerator, the beam is basically completely deposited in the reaction target or target liner, so in order to ensure the safe operation of the accelerator and the smooth development of the strong current experiment, the reaction target must be able to withstand the corresponding heat flux density.

[0003] The existing typical reaction targets that can withstand high heat flux density in the world are as follows:

[0004] 1. The reaction target liner of the commercial accelerator of the Dutch High Voltage Company adopts circulating water cooling of the back panel of the reaction target and is matched with a beam scanning device. The internal design of the target liner is unknown, but it is only suitable for a maximum beam intensity of tens of microamperes;

[0005] 2. The cooled high-power neutron conversion target of Spain can have a total power of up to 400kW (NIMA 724 (2013) 34). The device is large and very expensive, and is only suitable for special devices;

[0006] 3. The liquid metal cooled INFN neutron target of Italy can withstand a heat flux density of 3kW / cm 2 . It needs to be matched with an external liquid metal circulating system. The liquid metal is corrosive, so safety needs to be considered. In addition, the liquid metal and the copper shell have a great influence on the detection efficiency of gamma rays, and are not suitable for the measurement of extremely low cross-section experiments in the Jinping deep underground laboratory.

[0007] 4. The reaction target of the University of Stuttgart adopts a microporous structure, which is claimed to be able to withstand a heat flux density of 10kW / cm 2 (Phys. Rev. C 73 (2006) 055801). It is designed for the 4π high-purity germanium of the LUNA laboratory, and the technical details are not disclosed.

[0008] In summary, the existing high-power targets in the world are not suitable for the strong current experiment in the Jinping deep underground laboratory, and their technical details cannot be used for reference. We can only independently develop based on the needs we face. SUMMARY

[0009] In view of the defects in the prior art, the purpose of the present application is to provide a small high heat flux density nuclear reaction target which can realize more than 5kW / cm 2 The heat flow density is radiated, and when the cylindrical BGO detector (Science Bulletin 67 (2022) 125) is used in cooperation, the target replacement operation is facilitated, and the influence of the small and compact reaction target on the gamma detection efficiency is small.

[0010] To achieve the above purpose, the technical scheme adopted by the present application is: a small high heat flux density nuclear reaction target, the reaction target is arranged in the water circulation circuit at the end of the pipeline, the water circulation circuit includes the water inlet pipeline and the water outlet pipeline arranged at both sides of the end of the pipeline, and the heat dissipation pipeline arranged between the water inlet pipeline and the water outlet pipeline, the heat dissipation pipeline is enclosed by the reaction target and the cover plate, the two sides of the reaction target are connected with the end of the water inlet pipeline and the inlet of the water outlet pipeline respectively, and the micro groove structure is arranged at the back of the reaction target.

[0011] Further, the reaction target is 3mm thick, the micro groove is 0.2mm wide, 0.2mm apart, and 1.2mm deep.

[0012] Further, the micro groove structure on the back of the reaction target is processed by wire cutting, and the wire cutting uses a cutting wire with a diameter of 0.18mm.

[0013] Further, the micro groove structure on the back of the reaction target is processed by a numerical control milling machine, and the numerical control milling machine uses a milling cutter with a diameter of 0.2mm.

[0014] Further, a vacuum sealing ring is installed at the contact between the water inlet pipeline wall and the water outlet pipeline wall and the front surface of the reaction target.

[0015] Further, a water sealing ring is arranged at the contact between the side wall of the pipeline end and the cover plate.

[0016] Further, the cover plate is made of organic glass material.

[0017] Further, the reaction target is made of red copper plate material.

[0018] Further, the reaction target is 50mm in diameter.

[0019] Further, the thickness of the reaction target is 3mm.

[0020] The beneficial technical effect of the present application is that: the small high heat flux density nuclear reaction target disclosed by the present application is arranged in the water circulation circuit at the end of the pipeline, the water circulation circuit comprises the water inlet pipeline and the water outlet pipeline arranged at both sides of the end of the pipeline, and the heat dissipation pipeline arranged between the water inlet pipeline and the water outlet pipeline, the heat dissipation pipeline is enclosed by the reaction target and the cover plate, the two sides of the reaction target are connected with the end of the water inlet pipeline and the inlet of the water outlet pipeline respectively, and the micro groove structure is arranged at the back of the reaction target. The red copper plate with good heat conduction performance is used as the reaction target, the actual parameters of the micro groove are determined according to the thermodynamic simulation parameters, and the heat dissipation effect of the reaction target is optimized. The cover plate is made of organic glass material with small gamma ray absorption, and the nuclear reaction target disclosed in the present application can realize high-efficiency heat dissipation of more than 5kW / cm2 heat flux density, facilitate target replacement operation when the cylindrical detector is used in cooperation, and ensure that the reaction target is small enough and has little influence on the gamma detection efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a heat flux density distribution schematic diagram of the prior art with a total power of 1kW;

[0022] Figure 2 It is a structure schematic diagram of the small high heat flux density nuclear reaction target according to the embodiment of the present application;

[0023] Figure 3 It is a micro groove structure schematic diagram in the small high heat flux density nuclear reaction target according to the embodiment of the present application;

[0024] In the figure: 1-pipeline end, 2-reaction target, 3-micro groove structure, 4-vacuum sealing ring, 5-water sealing ring, 6-cover plate. DETAILED DESCRIPTION

[0025] The present application will be further described below in combination with the drawings and specific embodiments.

[0026] Embodiment one

[0027] The embodiment of the present application provides a small high heat flux density nuclear reaction target, a red copper plate with good heat conduction performance is used as the reaction target, the diameter is about 50mm, the thickness is controlled to be 3mm in order to minimize the influence on the gamma ray detection and to withstand the pressure of vacuum and cooling water, the front surface is polished for evaporation or sputtering reaction target material, and the edge position is sealed with an O-ring for vacuum.

[0028] In order to facilitate processing and control costs, the reaction target back plate is designed to have a micro groove structure and circulate water for cooling, according to thermodynamic simulation, the smaller the groove width and interval, the better the heat dissipation effect, and the change of the water groove depth has little effect on heat dissipation, finally, according to the simulation effect and combined with the actual processing precision, the water groove specifications are determined as 0.2mm in width, 0.2mm in interval and 1.2mm in depth.

[0029] like Figure 2 As shown, the front side of pipe end 1 is connected to the accelerator pipe. During normal operation, the interior of pipe end 1 is under vacuum. The sidewall of pipe end 1 is made of aluminum. Water circulation loops are set on both sides of pipe end 1, with inlet and outlet pipes respectively on each side. A heat dissipation pipe is installed between the inlet and outlet pipes, formed by the reaction target 2 and cover plate 6. The two sides of the reaction target 2 are connected to the end of the inlet pipe and the inlet of the outlet pipe, respectively. A microgroove structure 3 is set on the back of the reaction target 2. Vacuum sealing rings 4 are installed at the contact points between the inlet and outlet pipe walls and the front surface of the reaction target to achieve a vacuum seal inside the pipe. A water sealing ring 5 is installed at the contact point between the sidewall of pipe end 1 and cover plate 6 to seal the circulating water. The arrows indicate the direction of circulating water flow.

[0030] To facilitate testing and observation, cover plate 6 is made of plexiglass, which has low absorption of gamma rays, while other supporting materials such as vacuum pipes and screws are made of aluminum as much as possible.

[0031] The microgroove structure 3 on the back of the reaction target 2 can be processed in two ways. The first method is wire cutting, which requires a cutting wire diameter of 0.18 mm and high stability. The second method is machining with a CNC milling machine using a milling cutter with a diameter of 0.2 mm. The grooves produced by the first method have irregular edges and rounded bottoms. The grooves produced by the second method are relatively regular. However, due to the thinner milling cutter, the feed speed cannot be too fast. The first method requires continuous cleaning of the copper adhering to the cutting wire during long-term processing. Therefore, the processing time for both methods is roughly the same, about two hours to complete one piece.

[0032] The samples fabricated using this design underwent in-beam testing. At a 45-degree back angle, an infrared thermal imager was used to monitor the beam spot shape and the surface temperature of the reaction target through an observation window. A camera behind the reaction target monitored the circulating water through an acrylic base plate. During the test, a proton beam with an energy of 350 keV was used to bombard the reaction target, and the beam current intensity was continuously increased. From the ammeter readings and the infrared thermal imager images, the beam current intensity was observed to be approximately 6.07 mA, equivalent to a total power of 2.1 kW. At this point, boiling bubbles were observed in the trench. The highest temperature measured by the thermal imager stabilized at 118 degrees Celsius, still far below the safe temperature (the melting point of the target material).

[0033] By examining the 35mm aperture on the front surface of the test sample from a reaction target viewed at a 45-degree angle, the beam spot diameter can be calculated to be less than 8mm. Since the beam distribution cannot be measured under high-current conditions, the heat flux density can be estimated. Typically, the beam follows a normal distribution, in which case the central heat flux density is approximately 10.5 kW / cm². 2Even with a uniform beam distribution, the heat flux density exceeded 5.4 kW / cm². 2 Therefore, the heat flux density that the reaction target can withstand is 5.4–10.5 kW / cm³. 2 It has already exceeded the Jinping deep-earth high-current experiment by 5 kW / cm². 2 Requirements.

[0034] While the heat dissipation effect of the microgroove structure of this invention may not be as good as that of the microporous structure, the microgrooves are easier to manufacture, with a processing cost of approximately 500 yuan per target. Furthermore, the used target surface can be polished and reused repeatedly, further reducing the cost of using the target. Additionally, according to Geant4 simulations, the overall impact of this invention on gamma ray detection is less than 5%, and the invention also features convenient target replacement.

[0035] like Figure 3 As shown, the diameter of the reaction target can be adjusted as needed. In this embodiment, the target liner is 3 mm thick, and the microgrooves are 0.2 mm wide, spaced 0.2 mm apart, and 1.2 mm deep.

[0036] During the assembly process, attention must be paid to vacuum sealing and water sealing. After assembly, ensure that water circulation is normal before use. When changing targets, water must be stopped and the water in the assembly must be drained. Alcohol can be poured in to drain the water before opening the back cover, or after opening the back cover, use a blower to fully evaporate the water before removing the reaction target to ensure that water vapor does not affect the vacuum equipment in the pipeline.

[0037] As can be seen from the above embodiments, the present invention discloses a small high heat flux density nuclear reaction target. The reaction target is set in a water circulation loop at the end of a pipe. The water circulation loop includes an inlet pipe and an outlet pipe on both sides of the end of the pipe, and a heat dissipation pipe between the inlet pipe and the outlet pipe. The heat dissipation pipe is enclosed by the reaction target and a cover plate. The two sides of the reaction target are connected to the end of the inlet pipe and the inlet of the outlet pipe, respectively. A microgroove structure is set on the back of the reaction target. A copper plate with good thermal conductivity is used as the reaction target. The actual parameters of the microgrooves are determined according to thermodynamic simulation parameters, thus optimizing the heat dissipation effect of the reaction target. The cover plate is made of plexiglass material with low absorption of gamma rays. Using the nuclear reaction target disclosed in this invention, efficient heat dissipation with a heat flux density exceeding 5 kW / cm2 can be achieved. When used with a cylindrical detector, it facilitates target replacement operations, while ensuring that the reaction target is small enough to have a small impact on gamma detection efficiency.

[0038] The device described in this invention is not limited to the embodiments described in the specific implementation. Other implementation methods derived by those skilled in the art based on the technical solution of this invention also fall within the scope of technical innovation of this invention.

Claims

1. A small high heat flux nuclear reaction target characterized by: The reaction target is arranged in a water circulation circuit at the end of the pipeline, the water circulation circuit comprises a water inlet pipeline and a water outlet pipeline arranged at both sides of the end of the pipeline, and a heat dissipation pipeline arranged between the water inlet pipeline and the water outlet pipeline, the heat dissipation pipeline is enclosed by the reaction target and a cover plate, the cover plate is made of organic glass material to reduce the influence on the gamma detection efficiency, the two sides of the reaction target are connected with the end of the water inlet pipeline and the inlet of the water outlet pipeline respectively, and the front surface of the reaction target faces the end of the pipeline to facilitate the target replacement operation when the cylindrical detector is used, the reaction target is made of red copper plate to enhance the heat conduction performance of the reaction target, and the water inlet pipeline is arranged above the water outlet pipeline, and a micro groove structure is arranged at the back of the reaction target to enhance the heat dissipation effect when circulating water is circulated in the water circulation pipeline.

2. A small high heat flux nuclear target as in claim 1, wherein: The reaction target has a thickness of 3 mm, the micro groove has a width of 0.2 mm, an interval of 0.2 mm and a depth of 1.2 mm.

3. A small high heat flux nuclear target as in claim 1, wherein: the target is a cylindrical target having a length of 2.5 cm to 5 cm and a diameter of 1.5 cm to 3 cm. The micro groove structure at the back of the reaction target is processed by wire cutting, and the wire cutting uses a cutting wire with a diameter of 0.18 mm.

4. A small high heat flux nuclear target as in claim 1, wherein: The micro groove structure at the back of the reaction target is processed by a numerical control milling machine, and the numerical control milling machine uses a milling cutter with a diameter of 0.2 mm.

5. A small high heat flux density nuclear reaction target as described in claim 1, characterized in that: A vacuum sealing ring is arranged at the contact position between the wall of the water inlet pipeline and the wall of the water outlet pipeline and the front surface of the reaction target.

6. A small high heat flux nuclear target as in claim 5, wherein: A water sealing ring is arranged at the contact position between the side wall of the end of the pipeline and the cover plate.

7. A small high heat flux nuclear target as in claim 1, wherein: the target is a small high heat flux nuclear target. The reaction target has a diameter of 50 mm.

8. A small high heat flux nuclear target as in claim 1, wherein: The reaction target has a thickness of 3 mm.

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