Conductive-cooled superconducting magnet with liquid nitrogen precooling and nitrogen-fixed cold storage functions

Abstract

This invention discloses a conductive cooling superconducting magnet with liquid nitrogen precooling and solid nitrogen storage functions, belonging to the field of superconducting magnet technology. Its main purpose is to improve the cooling efficiency of superconducting coils, thereby shortening equipment start-up time and reducing energy waste during superconducting coil operation, thus lowering operating costs. The main technical solution of this invention is as follows: the conductive cooling superconducting magnet includes a superconducting coil; a conductive cooling assembly, which includes a refrigerator and a cooling conduction component, with the secondary cold head of the refrigerator connected to the cooling conduction component, and the cooling conduction component connected to the superconducting coil; a container connected to the cooling conduction component, the container including a liquid inlet and a gas outlet, the liquid inlet being used to supply liquid nitrogen into the container; the container has a liquid nitrogen precooling state and a solid nitrogen storage state. In the liquid nitrogen precooling state, the liquid nitrogen in the container precools the superconducting coil; in the solid nitrogen storage state, the liquid nitrogen in the container transforms into solid nitrogen under the action of the refrigerator.

Description

Technical Field

[0001] This invention relates to the field of superconducting magnet technology, and more specifically, to a conductive cooling superconducting magnet with liquid nitrogen precooling and fixed nitrogen storage cooling functions. Background Technology

[0002] Superconducting magnets have a wide range of applications in medical diagnosis and particle therapy, scientific research, and transportation.

[0003] Superconducting magnets operate in cryogenic environments. Conductive cooling is an important cooling technology for superconducting magnets. It involves direct contact between the cold head of the refrigerator and the cooling structure of the magnet, efficiently transferring the cooling energy to the superconducting coil. Compared with traditional cooling methods such as continuous liquid helium flow and liquid helium immersion, it has advantages such as high cooling efficiency and good operational stability.

[0004] However, existing conductive cooling superconducting magnets still have some problems and limitations in practical applications. On the one hand, in the initial startup phase, the process of cooling from room temperature to the superconducting magnet's operating temperature is relatively slow, which not only prolongs the equipment's startup time. On the other hand, in some applications requiring long-term stable operation, the magnet's cooling system consumes a large amount of energy to maintain the low-temperature environment, even when the magnet is in standby mode, resulting in energy waste and increased operating costs. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a conductive cooling superconducting magnet with liquid nitrogen precooling and solid nitrogen storage functions. The main purpose is to improve the cooling efficiency of the superconducting coil, so as to shorten the start-up time of the equipment and reduce energy waste during the operation of the superconducting coil, thereby reducing operating costs.

[0006] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0007] This invention provides a conductive cooling superconducting magnet with liquid nitrogen precooling and fixed nitrogen storage functions, comprising:

[0008] Superconducting coils;

[0009] A conductive cooling assembly, comprising a refrigerator and a heat conduction component, wherein the secondary cold head of the refrigerator is connected to the heat conduction component, and the heat conduction component is connected to the superconducting coil;

[0010] A container connected to the cooling assembly includes a liquid inlet and a gas outlet. The liquid inlet is used to supply liquid nitrogen into the container. The container has a liquid nitrogen pre-cooling state and a solid nitrogen storage state. In the liquid nitrogen pre-cooling state, the liquid nitrogen in the container pre-cools the superconducting coil. In the solid nitrogen storage state, the liquid nitrogen in the container changes into solid nitrogen under the action of the refrigerator.

[0011] Furthermore, a cooling material is provided inside the container, and the cooling material is in contact with the inner wall of the container.

[0012] Furthermore, the superconducting coil includes a main coil and two shielding coils, with the shielding coils disposed at corresponding ends of the main coil;

[0013] The conductive cooling superconducting magnet also includes multiple axial tie rods, which are connected between the two shielding coils and arranged circumferentially around the main coil. The axial tie rods are used to generate telescopic deformation in the length direction to adjust the relative displacement between the main coil and the shielding coil.

[0014] Furthermore, the superconducting coil also includes two annular end plates, and the shielded coil is connected to the main coil through the annular end plates;

[0015] The axial tie rod is connected between the two annular end plates.

[0016] Furthermore, the annular end plate is provided with a plurality of through holes, which are arranged at intervals along the circumference of the annular end plate, and the through holes are located between two adjacent axial tie rods.

[0017] Furthermore, the cooling component includes a first cooling element, a second cooling element, and a third cooling element. The first cooling element is connected between the two shielding coils, and the first cooling element is connected to the second cooling element and the third cooling element, respectively.

[0018] The secondary cold head of the refrigeration unit is connected to the first cooling conductor, the second cooling conductor is connected to the main coil, and the third cooling conductor is connected to the shielding coil.

[0019] The container is disposed between the first cooling element and the main coil, and is connected to the second cooling element.

[0020] Furthermore, the first cooling component includes a first cooling plate and a second cooling plate. The first cooling plate is a U-shaped plate. The first cooling plate includes a first arm and a second arm connected to each other. The first arm is connected to the secondary cold head of the refrigerator. The second arm is connected to the second cooling plate. The second cooling plate is connected between the two shielding coils. The second cooling plate is connected to the second cooling component and the third cooling component respectively.

[0021] The container is positioned between the second cooling plate and the main coil.

[0022] Furthermore, the second cooling component includes a first flexible cooling strip, a third cooling plate, a second flexible cooling strip, and a first copper sheet. The third cooling plate is disposed between the container and the main coil. The first flexible cooling strip covers the outside of the container. One end of the first flexible cooling strip is connected to the second cooling plate, and the other end of the first flexible cooling strip is connected to the third cooling plate. The first copper sheet covers the outside of the main coil, and the second flexible cooling strip covers the outside of the first copper sheet. One end of the second flexible cooling strip is connected to the third cooling plate.

[0023] Furthermore, the third cooling component includes a third flexible cooling strip and a second copper sheet, the second copper sheet covering the outside of the shielding coil, the third flexible cooling strip covering the outside of the second copper sheet, and the third flexible cooling strip being connected to the second cooling plate.

[0024] Furthermore, the conductive cooling superconducting magnet with liquid nitrogen precooling and fixed nitrogen storage functions also includes: a Dewar, a cold screen, a liquid inlet pipe, an outlet pipe, and multiple connecting rods, wherein the cold screen is disposed inside the Dewar; one end of the multiple connecting rods is connected to the container, and the other end of the multiple connecting rods passes through the cold screen and is connected to the top plate of the Dewar;

[0025] One end of the liquid inlet pipe is connected to the liquid inlet, and the other end of the liquid inlet pipe passes through the cold screen;

[0026] One end of the vent pipe is connected to the vent, and the other end of the vent pipe passes through the cold shield.

[0027] By employing the above technical solution, the present invention has at least the following beneficial effects:

[0028] The conductive cooling superconducting magnet with liquid nitrogen pre-cooling and solid nitrogen storage functions provided in this embodiment of the invention allows the container to be in a liquid nitrogen pre-cooling state when the superconducting magnet is started. The container rapidly pre-cools the cooling components through the liquid nitrogen stored inside. That is, the refrigerator and liquid nitrogen jointly pre-cool the superconducting coil through the cooling components to rapidly reduce the temperature of the superconducting coil. After the temperature of the superconducting coil drops to the liquid nitrogen temperature, the refrigerator continues to cool the superconducting coil through the cooling components until the temperature of the superconducting coil reaches its operating temperature. This significantly improves the cooling efficiency of the superconducting coil, greatly shortens the time required for the superconducting coil to drop from room temperature to operating temperature, and thus greatly shortens the start-up time of the superconducting magnet and the start-up time of the equipment.

[0029] Furthermore, during the operation of the superconducting magnet, a refrigerator provides cooling energy to maintain the low-temperature working environment. At this time, the container can be in a nitrogen-fixed cold storage state; that is, the liquid nitrogen inside the container transforms into solid nitrogen under the action of the refrigerator. When the superconducting coil unexpectedly loses its quench, the solid nitrogen can rapidly release its cooling energy, allowing the superconducting coil to quickly return to its operating temperature, thereby shortening the recovery time of the superconducting magnet. In other words, recovering, storing, and reusing the cooling energy generated during the operation of the superconducting magnet reduces energy waste, significantly saves operating costs, and expands the application range of superconducting magnets. Attached Figure Description

[0030] Figure 1 A schematic diagram of a conductive cooling superconducting magnet with liquid nitrogen precooling and solid nitrogen storage functions provided in an embodiment of the present invention from a first-view perspective;

[0031] Figure 2 A cross-sectional schematic diagram of a superconducting coil in a conductive cooling superconducting magnet with liquid nitrogen precooling and solid nitrogen storage functions, provided as an embodiment of the present invention;

[0032] Figure 3 A schematic diagram of a conductive cooling superconducting magnet with liquid nitrogen precooling and solid nitrogen storage functions provided in an embodiment of the present invention from a second-view perspective;

[0033] Figure 4 This is a schematic diagram of the structure of a container in a conductive cooling superconducting magnet with liquid nitrogen precooling and solid nitrogen storage functions, provided in an embodiment of the present invention.

[0034] Figure 5 A temperature distribution cloud map of a superconducting coil after cooling and stabilization of a conductive cooling superconducting magnet with liquid nitrogen pre-cooling and fixed nitrogen storage functions, provided for an embodiment of the present invention;

[0035] Figure 6 The graph shows the temperature variation over time of a superconducting coil with liquid nitrogen pre-cooling and solid nitrogen storage cooling functions in a conductive cooling superconducting magnet, as provided in an embodiment of the present invention, under different cooling methods. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Some embodiments of the invention will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0037] like Figure 1 As shown, this embodiment of the invention provides a conductive cooling superconducting magnet with liquid nitrogen precooling and solid nitrogen storage functions, including a superconducting coil 1; a conductive cooling assembly, which includes a refrigerator 2 and a cooling component 3, wherein the secondary cold head of the refrigerator 2 is connected to the cooling component 3, and the cooling component 3 is connected to the superconducting coil 1; and a container 4 connected to the cooling component 3, which includes a liquid inlet and a gas outlet, wherein the liquid inlet is used to deliver liquid nitrogen into the container 4; the container 4 has a liquid nitrogen precooling state and a solid nitrogen storage state. In the liquid nitrogen precooling state, the liquid nitrogen in the container 4 precools the superconducting coil 1, and in the solid nitrogen storage state, the liquid nitrogen in the container 4 is phase-transformed into solid nitrogen under the action of the refrigerator 2.

[0038] The number of refrigerators 2 can be two. The inlet of container 4 is used to supply liquid nitrogen into container 4. During the pre-cooling process of superconducting coil 1 by liquid nitrogen, the liquid nitrogen vaporizes and is discharged through the outlet. Then, liquid nitrogen can be input into container 4 through the inlet so that during the operation of the superconducting magnet, the liquid nitrogen will change into solid nitrogen under the action of refrigerator 2 and store the cooling capacity.

[0039] The container 4 can be made of a high-strength, high-thermal-conductivity material, such as stainless steel, to ensure good mechanical strength and withstand the low-temperature environment of liquid nitrogen and pressure changes during nitrogen fixation. Furthermore, the container 4 can be equipped with temperature sensors, pressure gauges, heaters, and other components to monitor parameters such as temperature and pressure in real time. The heaters can be activated based on the operating status and needs of the superconducting magnet, enabling control over the liquid and solid nitrogen states and ensuring effective storage and release of cold energy. In addition, the container 4 employs vacuum insulation, with multiple layers of insulation material wrapped around its exterior, giving it excellent thermal insulation properties. This reduces liquid nitrogen evaporation loss, improves liquid nitrogen utilization efficiency, and accelerates the pre-cooling and cooling process of the superconducting coil 1.

[0040] The conductive cooling superconducting magnet with liquid nitrogen pre-cooling and solid nitrogen storage functions provided in this embodiment of the invention allows the container 4 to be in a liquid nitrogen pre-cooling state when the superconducting magnet is started. The container 4 rapidly pre-cools the cooling component 3 through the liquid nitrogen stored inside it. That is, the refrigerator 2 and the liquid nitrogen jointly pre-cool the superconducting coil 1 through the cooling component 3, so that the temperature of the superconducting coil 1 drops rapidly. After the temperature of the superconducting coil 1 drops to the liquid nitrogen temperature, the refrigerator 2 continues to cool the superconducting coil 1 through the cooling component 3 until the temperature of the superconducting coil 1 reaches its working temperature. This significantly improves the cooling efficiency of the superconducting coil 1 and greatly shortens the time required for the superconducting coil 1 to drop from room temperature to working temperature, thereby greatly shortening the start-up time of the superconducting magnet and the start-up time of the equipment.

[0041] Furthermore, during the operation of the superconducting magnet, the refrigerator 2 provides cooling to maintain the low-temperature working environment of the superconducting magnet. At this time, the container 4 can be in a nitrogen-fixed cold storage state, that is, the liquid nitrogen in the container 4 changes phase to solid nitrogen under the action of the refrigerator 2. When the superconducting coil 1 accidentally loses its quench, the solid nitrogen can quickly release its cooling energy to allow the superconducting coil 1 to quickly return to its operating temperature, thereby shortening the recovery time of the superconducting magnet. In other words, the cooling energy generated during the operation of the superconducting magnet is recovered, stored, and reused, reducing energy waste, greatly saving operating costs, and expanding the application range of the superconducting magnet.

[0042] In some embodiments, a cooling material may be provided inside the container 4, and the cooling material is in contact with the inner wall of the container 4 so that the cooling capacity of the liquid nitrogen can be easily transferred to the wall of the container 4 through the cooling material, and then to the cooling assembly 3, thereby improving the cooling efficiency of the superconducting coil 1. Correspondingly, the cooling capacity of the refrigerator 2 can also be easily transferred to the cooling material through the wall of the container 4, thereby improving the solidification efficiency of the liquid nitrogen inside the container 4.

[0043] Among them, the cooling material can be superconducting materials such as graphene or copper composite strip.

[0044] In some embodiments, see Figure 2 The superconducting coil 1 may include a main coil 11 and two shielding coils 12. The shielding coils 12 are disposed at the corresponding ends of the main coil 11, and the two shielding coils 12 are symmetrically disposed at both ends of the main coil 11. The conductive cooling superconducting magnet may also include a plurality of axial tie rods 5. The plurality of axial tie rods 5 are connected between the two shielding coils 12 and are arranged circumferentially around the main coil 11. The axial tie rods 5 are used to generate extension and contraction deformation in the length direction to adjust the relative displacement between the main coil 11 and the shielding coils 12.

[0045] The axial tie rod 5 can be made of aluminum alloy, while the coil frame can be made of stainless steel. Stainless steel and aluminum alloy have different coefficients of thermal expansion. This difference can be used to achieve the following: in low-temperature environments, the axial tie rod 5 contracts, its length decreases, and the distance between the main coil 11 and the shielding coil 12 decreases. When the superconducting coil 1 is energized, the axial tie rod 5 extends, and the distance between the main coil 11 and the shielding coil 12 increases. This controls the relative position between the main coil 11 and the shielding coil 12, ensuring that the main coil 11 and the shielding coil 12 reach the preset relative position, thereby ensuring the magnetic field quality of the superconducting coil 1.

[0046] In some embodiments, see Figure 2 The superconducting coil 1 may also include two annular end plates 13, which may be made of stainless steel. The shielding coil 12 is connected to the main coil 11 through the annular end plates 13. An axial tie rod 5 is connected between the two annular end plates 13. The axial tie rod 5 is used to constrain the shielding coil 12 to separate axially relative to the main coil 11, ensuring the relative distance between the main coil 11 and the shielding coil 12.

[0047] In some embodiments, see Figure 2 The annular end plate 13 is provided with multiple through holes 131, which are arranged at intervals along the circumference of the annular end plate 13. The through holes 131 are located between two adjacent axial tie rods 5.

[0048] By setting multiple through holes 131 on the annular end plate 13, the annular end plate 13 forms a hollow structure design, which helps to reduce the cold mass of the annular end plate 13, thereby reducing the cold mass of the superconducting coil 1.

[0049] In some embodiments, the outer layers of both the main coil 11 and the shielding coil 12 can be wound with aluminum alloy wire to control and manage stress, ensuring the shape and quality of the magnetic field. Furthermore, the conductors of both the main coil 11 and the shielding coil 12 can be wound with high-performance superconducting materials (such as niobium-tin alloy or niobium-titanium alloy), enabling the superconducting coil 1 to carry a large current and generate a high-intensity magnetic field.

[0050] In some embodiments, see Figure 3 The cooling component 3 may include a first cooling component 31, a second cooling component 32, and a third cooling component 33. The first cooling component 31 is connected between two shielded coils 12, and the first cooling component 31 is connected to the second cooling component 32 and the third cooling component 33 respectively. The secondary cold head of the refrigerator 2 is connected to the first cooling component 31, the second cooling component 32 is connected to the main coil 11, and the third cooling component 33 is connected to the shielded coil 12. The container 4 is disposed between the first cooling component 31 and the main coil 11, and is connected to the second cooling component 32.

[0051] When the superconducting magnet is started, container 4 can be in a liquid nitrogen pre-cooling state. That is, container 4 rapidly pre-cools the second cooling element 32 with the liquid nitrogen stored inside. The second cooling element 32 quickly transfers the cooling energy to the main coil 11. At the same time, the liquid nitrogen transfers the cooling energy to the third cooling element 33 through the first cooling element 31. The third cooling element 33 quickly transfers the cooling energy to the shielding coil 12, so that the temperature of the superconducting coil 1 drops rapidly. Then, the refrigerator 2 can be started. Its secondary cold head continues to cool the superconducting coil 1 through the first cooling element 31, the second cooling element 32 and the third cooling element 33 until the temperature of the superconducting coil 1 reaches its working temperature. This shortens the time for the superconducting coil 1 to drop from room temperature to working temperature, improves the cooling efficiency of the superconducting coil 1, and thus shortens the start-up time of the equipment.

[0052] Furthermore, during the operation of the superconducting magnet, the cooling energy of the refrigerator 2 is transferred to the container 4 through the first cooling conductor 31 and the second cooling conductor 32, so that the liquid nitrogen in the container 4 is converted into solid nitrogen to store the cooling energy. When the superconducting coil 1 accidentally loses its quench, the solid nitrogen can quickly release the cooling energy, so that the superconducting coil 1 can quickly return to the operating temperature, thereby shortening the recovery time of the superconducting magnet.

[0053] In addition, the cooling capacity of the refrigerator 2 and the container 4 is transferred to the main coil 11 and the shielding coil 12 respectively through the cooling conductive component 3, so that the temperature distribution of the superconducting coil is uniform and the stable operation of the superconducting magnet is ensured.

[0054] In some embodiments, see Figure 3 The first cooling component 31 may include a first cooling plate 311 and a second cooling plate 312. The first cooling plate 311 is a U-shaped plate and includes a first arm and a second arm connected to each other. The first arm is connected to the secondary cold head of the refrigerator 2, and the second arm is connected to the second cooling plate 312. The second cooling plate 312 is connected between two shielded coils 12 and is connected to the second cooling component 32 and the third cooling component 33 respectively. The container 4 is disposed between the second cooling plate 312 and the main coil 11.

[0055] The cooling capacity of the refrigerator 2 can be transferred from the first cooling plate 311 to the second cooling plate 312, and then from the second cooling plate 312 to the second cooling component 32 and the third cooling component 33. The first cooling plate 311 is a U-shaped plate, which gives it a certain degree of elasticity. This allows for a flexible connection between the secondary cold head of the refrigerator 2 and the second cooling plate 312, rather than a rigid one. During the start-up or operation of the superconducting magnet, the first cooling plate 311 can deform under external force, thus preventing damage to the refrigerator 2 and other components.

[0056] In some embodiments, see Figure 3The second cooling component 32 may include a first flexible cooling strip 321, a third cooling plate 322, a second flexible cooling strip 323, and a first copper sheet 324. The third cooling plate 322 is disposed between the container 4 and the main coil 11. The first flexible cooling strip 321 covers the outside of the container 4. One end of the first flexible cooling strip 321 is connected to the second cooling plate 312, and the other end of the first flexible cooling strip 321 is connected to the third cooling plate 322. The first copper sheet 324 covers the outside of the main coil 11. The second flexible cooling strip 323 covers the outside of the first copper sheet 324, and one end of the second flexible cooling strip 323 is connected to the third cooling plate 322.

[0057] The cooling capacity of the refrigerator 2 is transferred to the second flexible cooling belt 323 via the first cooling plate 311, the second cooling plate 312, the first flexible cooling belt 321, and the third cooling plate 322, and then to the first copper sheet 324 via the second flexible cooling belt 323, and then to the main coil 11 via the first copper sheet 324; the cooling capacity of the container 4 is transferred to the first copper sheet 324 via the first flexible cooling belt 321, the third cooling plate 322, and the second flexible cooling belt 323, and then to the main coil 11 via the second flexible cooling belt 323; the cooling capacity of the refrigerator 2 is transferred to the first flexible cooling belt 321 and the third cooling plate 322 via the first cooling plate 311 and the second cooling plate 312, and then to the container 4 via the first flexible cooling belt 321 and the third cooling plate 322.

[0058] The first flexible cooling strip 321 and the second flexible cooling strip 323 can both be flexible copper braided strips. The first flexible cooling strip 321 is wrapped around the outside of the container 4, and the second flexible cooling strip 323 is wrapped around the outside of the main coil 11. This can buffer the external force caused by the deformation of the container 4 and the superconducting coil 1 due to factors such as temperature changes, thereby avoiding deformation or even damage to the cooling components.

[0059] The outer wall of container 4 can be connected to a fourth cold-conducting plate 41, and the first flexible cold-conducting strip 321 is connected to the fourth cold-conducting plate 41 to improve the efficiency of cold transfer between container 4 and the first flexible cold-conducting strip 321.

[0060] Specifically, each cooling component can be made of materials with good thermal conductivity, such as copper or aluminum. Both the main coil 11 and the shielding coil 12 can be wrapped with copper foil. The copper foil not only serves to conduct heat but also to shield interference, reduce leakage inductance, and reduce excitation current.

[0061] In some embodiments, see Figure 3The third cooling component 33 may include a third flexible cooling strip 331 and a second copper sheet. The second copper sheet covers the outside of the shielding coil 12, and the third flexible cooling strip 331 covers the outside of the second copper sheet. The third flexible cooling strip 331 is connected to the second cooling plate 312.

[0062] The cooling capacity of the refrigeration unit 2 is transferred to the third flexible cooling belt 331 via the first cooling plate 311 and the second cooling plate 312, and then transferred to the shielding coil 12 via the third flexible cooling belt 331 and the second copper sheet; the cooling capacity of the container 4 is transferred to the second cooling plate 312 via the first flexible cooling belt 321, and then transferred to the shielding coil 12 via the second cooling plate 312.

[0063] The third flexible cooling strip 331 can be a flexible copper braided strip. When the third flexible cooling strip 331 is wrapped around the outside of the shielding coil 12, it can buffer the external force caused by the deformation of the superconducting coil 1 due to factors such as temperature changes, thereby avoiding deformation or even damage to the cooling component.

[0064] In some embodiments, see Figure 3 and Figure 4 The conductive cooling superconducting magnet may further include a Dewar, a cold screen 6, a liquid inlet pipe 7, an exhaust pipe 8, and multiple connecting rods 9. The cold screen 6 is disposed inside the Dewar. One end of each connecting rod 9 is connected to the container 4, and the other end of each connecting rod 9 passes through the cold screen 6 and connects to the top plate of the Dewar. One end of the liquid inlet pipe 7 is connected to the liquid inlet, and the other end of the liquid inlet pipe 7 passes through the cold screen 6. One end of the exhaust pipe 8 is connected to the exhaust outlet, and the other end of the exhaust pipe 8 passes through the cold screen 6. The container 4 is suspended from the top plate of the Dewar by the multiple connecting rods 9, which facilitates the stable installation of the container 4.

[0065] Figure 5 The temperature distribution contour map of superconducting coil 1 after the superconducting magnet has been cooled and stabilized is shown. (See diagram below.) Figure 5 As shown, the temperature of superconducting coil 1 is below 4.2K (lower than the design temperature), and the temperature distribution of superconducting coil 1 is uniform, with a maximum temperature difference of 0.5K. The highest temperature is located inside the frame of the main coil 11. All temperatures are below the shunt temperature of superconducting coil 1. Preliminary thermal analysis results indicate that the conductive cooling component effectively conducts cold energy to superconducting coil 1, while the temperature of the supporting structure remains within acceptable limits. The overall temperature distribution of superconducting coil 1 is uniform, meeting the design requirements of the superconducting magnet and ensuring its stable operation.

[0066] Appendix Figure 6 The temperature of superconducting coil 1 over time is shown under different cooling methods. The horizontal axis represents the cooling time (in hours), and the vertical axis represents the temperature of superconducting coil 1 (in Kelvin, K). Figure 6 The image shows three broken lines, representing the following three situations:

[0067] (a) One small refrigerator: The temperature gradually decreased from room temperature (about 300K) and stabilized at about 4.2K after about 540 hours.

[0068] (b) Two small refrigerators: The cooling rate was significantly faster, and the temperature reached 4.2K and stabilized after about 270 hours.

[0069] (c) Two small refrigerators + liquid nitrogen pre-cooling: the fastest cooling speed, stabilizing the temperature at around 4.2K in just about 92 hours.

[0070] from Figure 6 As can be seen, liquid nitrogen precooling significantly improves the cooling efficiency of superconducting coil 1 and greatly shortens the time required for the superconducting magnet to reach the working temperature.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A conductive cooling superconducting magnet with liquid nitrogen precooling and fixed nitrogen storage functions, characterized in that, include: Superconducting coils; A conductive cooling assembly, comprising a refrigerator and a heat conduction component, wherein the secondary cold head of the refrigerator is connected to the heat conduction component, and the heat conduction component is connected to the superconducting coil; A container connected to the cooling assembly includes a liquid inlet and a gas outlet. The liquid inlet is used to supply liquid nitrogen into the container. The container has a liquid nitrogen pre-cooling state and a solid nitrogen storage state. In the liquid nitrogen pre-cooling state, the liquid nitrogen in the container pre-cools the superconducting coil. In the solid nitrogen storage state, the liquid nitrogen in the container changes phase to solid nitrogen under the action of the refrigerator. The superconducting coil includes a main coil; The cooling component includes a first cooling element and a second cooling element; The first cooling component includes a second cooling plate; The second cooling component includes a first flexible cooling strip, a third cooling plate, a second flexible cooling strip, and a first copper sheet. The third cooling plate is disposed between the container and the main coil. The first flexible cooling strip covers the outside of the container. One end of the first flexible cooling strip is connected to the second cooling plate, and the other end of the first flexible cooling strip is connected to the third cooling plate. The first copper sheet covers the outside of the main coil, and the second flexible cooling strip covers the outside of the first copper sheet. One end of the second flexible cooling strip is connected to the third cooling plate.

2. The superconducting magnet with liquid nitrogen precooling and fixed nitrogen storage cooling functions according to claim 1, characterized in that, The container is provided with a cooling material, which is in contact with the inner wall of the container.

3. The superconducting magnet with liquid nitrogen precooling and fixed nitrogen storage cooling functions according to claim 1, characterized in that, The superconducting coil includes two shielding coils, which are disposed at the corresponding ends of the main coil; The conductive cooling superconducting magnet also includes multiple axial tie rods, which are connected between the two shielding coils and arranged circumferentially around the main coil. The axial tie rods are used to generate telescopic deformation in the length direction to adjust the relative displacement between the main coil and the shielding coil.

4. The superconducting magnet with liquid nitrogen precooling and fixed nitrogen storage cooling functions according to claim 3, characterized in that, The superconducting coil also includes two annular end plates, and the shielded coil is connected to the main coil through the annular end plates. The axial tie rod is connected between the two annular end plates.

5. The superconducting magnet with liquid nitrogen precooling and fixed nitrogen storage cooling functions according to claim 4, characterized in that, The annular end plate is provided with multiple through holes, which are arranged at intervals along the circumference of the annular end plate, and the through holes are located between two adjacent axial tie rods.

6. The superconducting magnet with liquid nitrogen precooling and fixed nitrogen storage cooling functions according to claim 3, characterized in that, The cooling component includes a third cooling element, the first cooling element is connected between the two shielding coils, and the first cooling element is connected to the second cooling element and the third cooling element respectively; The secondary cold head of the refrigeration unit is connected to the first cooling conductor, the second cooling conductor is connected to the main coil, and the third cooling conductor is connected to the shielding coil. The container is disposed between the first cooling element and the main coil, and is connected to the second cooling element.

7. The superconducting magnet with liquid nitrogen precooling and fixed nitrogen storage cooling functions according to claim 6, characterized in that, The first cooling component includes a first cooling plate, which is a U-shaped plate. The first cooling plate includes a first arm and a second arm connected to each other. The first arm is connected to the secondary cold head of the refrigerator, and the second arm is connected to the second cooling plate. The second cooling plate is connected between the two shielding coils and is connected to the second cooling component and the third cooling component respectively. The container is positioned between the second cooling plate and the main coil.

8. The superconducting magnet with liquid nitrogen precooling and fixed nitrogen storage cooling functions according to claim 7, characterized in that, The third cooling component includes a third flexible cooling strip and a second copper sheet. The second copper sheet covers the outside of the shielding coil, and the third flexible cooling strip covers the outside of the second copper sheet. The third flexible cooling strip is connected to the second cooling plate.

9. The superconducting magnet with liquid nitrogen precooling and fixed nitrogen storage cooling functions according to claim 6, characterized in that, Also includes: Dewar, cooling screen, liquid inlet pipe, gas outlet pipe, and multiple connecting rods; The cold shield is disposed inside the Dewar; One end of each of the multiple connecting rods is connected to the container, and the other end of each of the multiple connecting rods passes through the cold shield and is connected to the top plate of the Dewar; One end of the liquid inlet pipe is connected to the liquid inlet, and the other end of the liquid inlet pipe passes through the cold screen; One end of the vent pipe is connected to the vent, and the other end of the vent pipe passes through the cold shield.

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