Superconducting coil framework, superconducting magnet and cooling method thereof

Abstract

The invention relates to the technical field of superconducting magnets, in particular to a superconducting coil framework, a superconducting magnet and a cooling method thereof.The superconducting coil framework comprises a main frame body, the main frame body is provided with a plurality of installation grooves used for containing a plurality of superconducting coils in a one-to-one correspondence mode, and the main frame body is hollow and forms a cooling cavity; the at least two mounting bottom plates are oppositely arranged to form a group, and the included angle alpha between the central axis of one group of oppositely arranged mounting bottom plates and the central axis of the other adjacent group of oppositely arranged mounting bottom plates is 66 degrees. The included angle of 66 degrees can improve the magnetic field intensity of the center of the superconducting magnet formed by the superconducting coil framework and the superconducting coil and optimize the distribution of the magnetic field intensity; axial acting force generated by the superconducting coil can be transmitted to the mounting bottom plate, and the mounting bottom plate can provide enough supporting force to support the superconducting coil. And a refrigerant can be introduced into the cooling cavity of the main frame body to pre-cool the main frame body and the mounting bottom plate, so that the pre-cooling of the superconducting coil is realized.

Description

Technical Field

[0001] This application relates to the field of superconducting magnet technology, and in particular to a superconducting coil frame, a superconducting magnet and a cooling method thereof. Background Technology

[0002] In superconducting magnets used for magnetron-controlled single crystal growth, especially those used to generate horizontal magnetic fields, superconducting coils are typically fixed to a coil frame. Inappropriate placement of adjacent superconducting coils can lead to a weaker magnetic field at the center of the superconducting magnet under the same conditions. Furthermore, the bolted connection of the superconducting coil to the coil frame presents several challenges. First, the axial force exerted by the superconducting coil is substantial, and this force can only be transmitted to the coil frame through the bolts. This results in the coil frame failing to provide sufficient axial support for the superconducting coil, negatively impacting its stability. Second, this connection method necessitates cooling through methods such as winding cooling pipes or installing cooling boxes around the coil frame, making the manufacturing process cumbersome. Summary of the Invention

[0003] This application provides a superconducting coil frame, a superconducting magnet, and a cooling method thereof to solve the problems in the prior art where unreasonable superconducting coil positioning leads to a weak central magnetic field, the coil frame cannot provide sufficient axial support force leading to instability of the superconducting coil, and the superconducting coil's heat conduction connection is not conducive to cooling.

[0004] On one hand, this application provides a superconducting coil frame, including: a main frame body, formed into a ring shape, having multiple mounting slots for correspondingly accommodating multiple superconducting coils, the multiple mounting slots being arranged at intervals along the circumference of the main frame body, the main frame body being hollow to form a cooling cavity; and mounting base plates, configured to be respectively attached to the bottom of the mounting slots, at least two mounting base plates being arranged opposite each other to form a group, and at least two groups of mounting base plates being provided, wherein the angle α between the central axis of one group of oppositely arranged mounting base plates and the central axis of the adjacent group of oppositely arranged mounting base plates is 66°, the mounting base plates being used to attach and connect the superconducting coils, so as to provide axial support force for the superconducting coils together with the main frame body, and to transfer the temperature of the cooling cavity to the superconducting coils.

[0005] Preferably, the mounting slot is located on the inner side of the main frame.

[0006] Preferably, there are four mounting slots, with two mounting slots forming a group. The two groups of mounting slots are symmetrically arranged, and the center angle of the mounting base plate on each of the two mounting slots in each group is α.

[0007] Preferably, the center of the mounting base is located in the same horizontal plane.

[0008] Preferably, the mounting base plate includes a plate body formed in the shape of a disc, a plurality of reinforcing ribs disposed on the plate body, and a connecting plate connected to the reinforcing ribs. The reinforcing ribs are disposed on the side of the plate body away from the center of the main frame body, the plurality of reinforcing ribs are arranged at intervals along the circumference of the plate body, and the reinforcing ribs are connected to the main frame body through the connecting plate.

[0009] Preferably, the main frame includes a support plate disposed on the edge of the mounting groove, and the support plate and the mounting base plate cooperate to form a mounting area for mounting the superconducting coil, the depth of the mounting area being greater than or equal to the thickness of the superconducting coil.

[0010] Preferably, the main frame also has a liquid nitrogen inlet, a liquid nitrogen outlet and a first air extraction port connected to the cooling chamber. Liquid nitrogen can be introduced into the cooling chamber through the liquid nitrogen inlet and liquid nitrogen or a mixture of liquid nitrogen and nitrogen can be discharged through the liquid nitrogen outlet. Air can be discharged through the first air extraction port to form a vacuum state.

[0011] On the other hand, this application also provides a superconducting magnet, including: a superconducting coil; and the superconducting coil frame described above, wherein the superconducting coil is mounted to a mounting groove.

[0012] Preferably, the superconducting magnet further includes a cold screen and a Dewar. The cold screen is hollow, forming a first mounting cavity. The superconducting coil frame is disposed in the first mounting cavity. The Dewar is hollow, forming a second mounting cavity. The Dewar has a second evacuation port connected to the second mounting cavity. The second mounting cavity can be made into a vacuum state through the second evacuation port. The cold screen is disposed in the second mounting cavity.

[0013] Furthermore, this application also provides a cooling method for a superconducting magnet, applied to the aforementioned superconducting magnet, comprising the following steps:

[0014] The second mounting cavity in Dewar and the cooling cavity inside the main frame are evacuated to a vacuum state;

[0015] Liquid nitrogen is introduced into the cooling chamber, and the refrigeration unit is started simultaneously;

[0016] Pre-cooling begins, with the refrigerator cooling the cold screen and superconducting coil frame through conduction cooling, and the liquid nitrogen in the cooling chamber cooling the superconducting coil frame through heat exchange, until the temperature of the first mounting cavity, the superconducting coil frame and the superconducting coil are the same as the temperature of the liquid nitrogen in the cooling chamber.

[0017] Extract the liquid nitrogen from the cooling chamber and restore the cooling chamber to a vacuum state;

[0018] The refrigerator continues to cool the cold screen and the superconducting coil frame through conduction cooling until the temperature of the first mounting cavity, the superconducting coil frame, and the superconducting coil reaches the operating temperature of the superconducting coil.

[0019] The beneficial effects of this application are as follows:

[0020] The mounting slot is equipped with a mounting base plate on which the superconducting coil can be mounted. Firstly, the central axis of one set of opposing mounting base plates forms a 66° angle with the central axis of another set of opposing mounting base plates. This ensures that the central axis of the superconducting coils on one set of mounting base plates forms a 66° angle with the corresponding superconducting coils on the other set of mounting base plates. This positioning enhances the magnetic field strength at the center of the superconducting magnet composed of the superconducting coil frame and the superconducting coils, and optimizes the magnetic field strength distribution. Secondly, the axial force generated by the superconducting coils can be transmitted to the mounting base plate, which provides sufficient support to enhance the stability of the superconducting coils. Thirdly, a refrigerant such as liquid nitrogen can be introduced into the cooling chamber of the main frame to pre-cool the main frame and mounting base plates, thereby pre-cooling the superconducting coils. This eliminates the need for external cooling pipes or cooling boxes around the superconducting coil frame, simplifying the manufacturing process.

[0021] The superconducting magnet and its cooling method provided in this application incorporate all the advantages of the superconducting coil frame described above, since they include the superconducting coil frame described in this application. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 A perspective view of the superconducting coil skeleton provided in the embodiments of this application;

[0024] Figure 2 for Figure 1 Top view;

[0025] Figure 3 A perspective view of a superconducting magnet provided in an embodiment of this application, wherein the cold screen and Dewar are not shown;

[0026] Figure 4 for Figure 3 Longitudinal cross-section of a superconducting magnet;

[0027] Figure 5 Simulation diagram of the magnetic field strength and magnetic field distribution of the superconducting magnet in the crucible provided in the embodiments of this application.

[0028] Figure label:

[0029] 10. Superconducting coil frame; 11. Main frame; 111. Mounting slot; 112. Support plate; 113. Upper frame; 114. Lower frame; 115. Connecting column; 116. Cooling chamber; 12. Mounting base plate; 121. Plate; 122. Reinforcing rib; 123. Connecting plate; 20. Superconducting coil; 30. Cooling shield; 31. First mounting chamber; 40. Dewar; 41. Inner cylinder; 42. Outer cylinder; 43. Upper cover plate; 44. Lower cover plate; 45. Second mounting chamber; 51. Cooling guide plate; 52. Cooling guide connecting plate; 61. Second tie rod; 62. Third tie rod. Detailed Implementation

[0030] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] The following is combined Figures 1 to 4 This application describes the superconducting coil frame 10, the superconducting magnet, and the cooling method thereof provided in the embodiments of this application.

[0032] The superconducting coil frame 10 includes: a main frame 11, which is formed in an annular shape and has multiple mounting slots 111 for correspondingly accommodating multiple superconducting coils 20. The multiple mounting slots 111 are arranged at intervals along the circumference of the main frame 11. The main frame 11 is hollow and forms a cooling cavity 116. The mounting base plates 12 are configured to be attached to the bottom of the mounting slots 111 in a corresponding manner. At least two mounting base plates 12 are arranged opposite each other to form a group, and at least two groups of mounting base plates 12 are provided. The angle α between the central axis of one group of oppositely arranged mounting base plates 12 and the central axis of the adjacent group of oppositely arranged mounting base plates 12 is 66°. The mounting base plates 12 are used to attach and connect the superconducting coils 20 so as to provide stable axial support force for the superconducting coils 20 together with the main frame 11 and transfer the temperature of the cooling cavity 116 to the superconducting coils 20.

[0033] The superconducting coil frame 10 is used to mount the superconducting coil 20 and cooperates with the superconducting coil 20 to form a superconducting magnet. The mounting slot 111 is used to insert the superconducting coil 20, which can be mounted on the mounting base plate 12 within the mounting slot 111. The superconducting coil 20 is also a ring structure, concentrically arranged with the mounting base plate 12. The angle α between the central axes of two opposing mounting base plates 12 in one group and the central axes of two opposing mounting base plates 12 in an adjacent group is 66°. This ensures that the angle between the central axes of the two opposing superconducting coils 20 corresponding to the two opposing mounting base plates 12 in one group and the central axes of the two opposing superconducting coils 20 corresponding to the two opposing mounting base plates 12 in another group is 66°, thereby increasing the magnetic field strength at the center of the superconducting magnet and optimizing the magnetic field strength distribution. Figure 5 As shown, when the superconducting magnet is used for the preparation of 300mm magnetron-controlled Czochralski single crystals, the magnetic field strength generated by the superconducting coil 20 in the crucible of the single crystal furnace is uniformly distributed, especially the circumferentially uniform magnetic field strength near the crucible wall. This effectively suppresses the generation of oxygen on the crucible wall and reduces the oxygen content in the single crystal rod, which is beneficial to improving the quality of the single crystal rod. When the superconducting coil 20 is working, it generates an axial force that can be directly transmitted to the mounting base 12. The mounting base 12 generates a reaction force to the superconducting coil 20, which provides sufficient support for the superconducting coil 20, thereby improving its stability. The superconducting coil 20 needs to be cooled to a suitable operating temperature. To reduce cooling time and improve cooling efficiency, the main frame 11 is hollowed out to form a cooling chamber 116. A refrigerant such as liquid nitrogen can be introduced into the cooling chamber 116 to pre-cool the main frame 11 and the mounting base 12, thereby cooling the superconducting coil 20 and achieving pre-cooling of the superconducting coil 20. In addition, the superconducting magnet's cooler (described in detail later) can continue to cool the superconducting coil 20, while the cooling shield 30 (described in detail later) and Dewar 40 (described in detail later) can maintain the low-temperature environment of the superconducting magnet. Compared with the existing technology of winding cooling pipes or setting cooling boxes around the outer periphery of the superconducting coil frame 10, this application adopts a combined cooling method of introducing refrigerant into the cooling cavity 116 of the superconducting coil frame 10 and conducting cooling of the superconducting coil frame 10 through a cooler. This can effectively reduce the manufacturing difficulty, cost, and maintenance difficulty of the superconducting magnet, and improve the cooling efficiency of the superconducting coil 20.

[0034] The main frame 11 is a hollow structure, with low mass, which saves on manufacturing costs and reduces heat radiation, thus facilitating rapid cooling of the superconducting coil 20. The main frame 11 can be made of stainless steel, ensuring structural strength and rigidity while accelerating cooling. The main frame 11 includes an annular upper frame 113 and a lower frame 114, as well as connecting columns 115 that connect the upper and lower frames 113 and 114. All three are hollow. The upper and lower frames 113 and 114 have the same diameter and are coaxially arranged, connected by multiple connecting columns 115 spaced circumferentially along the upper and lower frames 114. The upper frame 113, lower frame 114, and connecting columns 115 are internally interconnected to form a cooling chamber 116, through which a refrigerant such as liquid nitrogen can enter the upper frame 113. Within frame 13, liquid nitrogen flows through connecting column 115 to the lower frame 114 to pre-cool the main frame 11, mounting base plate 12, and superconducting coil 20 (at this time, the chiller also conducts heat to cool the main frame 11, mounting base plate 12, and superconducting coil 20). The pre-cooled liquid nitrogen (which may also heat up to form a mixture of liquid nitrogen and nitrogen gas) flows from the lower frame 114 through connecting column 115 to the upper frame 113 and then out of the upper frame 113. The upper frame 113, lower frame 114, and connecting column 115 are all formed by welding plates.

[0035] Please refer to Figure 1 and Figure 2 ,in, Figure 1 and Figure 2 These are a perspective view and a top view of the superconducting coil skeleton 10 provided in the embodiments of this application.

[0036] In some embodiments, the mounting groove 111 is located on the inner side of the main frame 11.

[0037] In some embodiments, four mounting slots 111 are provided, with each pair of mounting slots 111 forming a group. The two groups of mounting slots 111 are symmetrically arranged, and the central angle of the mounting base plate 12 provided on the two mounting slots 111 in each group is α.

[0038] by Figure 2 The orientation is described as shown, with the horizontal center line of the main frame 11 as the line of symmetry. Two mounting slots 111 above the line of symmetry form one group, and two mounting slots 111 below the line of symmetry form another group. The two groups of mounting slots 111 are symmetrical about the line of symmetry. In this embodiment, the central angle α of the mounting base plate 12 on the two mounting slots 111 in each group is 66°. With this configuration, when the superconducting magnet is used for the preparation of 300mm magnetron-controlled Czochralski single crystals, a result can be obtained in the crucible as shown... Figure 5 The optimal magnetic field strength and magnetic field distribution are shown.

[0039] Please refer to Figure 1In some embodiments, the centers of all mounting base plates 12 are located in the same horizontal plane.

[0040] With the above settings, the centers of all the superconducting coils 20 set on the mounting base plate 12 can also be located in the same horizontal plane, so as to generate a horizontal magnetic field.

[0041] Please continue reading. Figure 1 In some embodiments, the mounting base plate 12 includes a plate body 121 formed in the shape of a disc, a plurality of reinforcing ribs 122 disposed on the plate body 121, and a connecting plate 123 connected to the reinforcing ribs 122. The reinforcing ribs 122 are disposed on the side of the plate body 121 away from the center of the main frame 11. The plurality of reinforcing ribs 122 are arranged at intervals along the circumference of the plate body 121. The reinforcing ribs 122 are connected to the main frame 11 through the connecting plate 123.

[0042] When the superconducting coil 20 is working, it generates an axial force. The mounting base plate 12 is used to bear this force and support the superconducting coil 20. Specifically, the plate 121 is used to attach and connect the superconducting coil 20, the reinforcing rib 122 is used to increase the overall structural strength of the mounting base plate 12, enabling it to withstand the axial force generated by the superconducting coil 20 and to stably support it, and the connecting plate 123 is used to connect the reinforcing rib 122 to the main frame 11. This allows a portion of the force from the superconducting coil 20 borne by the plate 121 to be transferred to the main frame 11 through the reinforcing rib 122 and the connecting plate 123, thus enabling the main frame 11 to share the force borne by the plate 121 and the reinforcing rib 122.

[0043] The plate 121 is formed into a circular plate structure, the connecting plate 123 is formed into an arc shape, and multiple reinforcing ribs 122 are connected to each connecting plate 123 to increase the structural strength of the multiple reinforcing ribs 122.

[0044] Please continue reading. Figure 1 In some embodiments, the main frame 11 includes a support plate 112 disposed on the edge of the mounting groove 111. The support plate 112 and the mounting base plate 12 cooperate to form a mounting area for mounting the superconducting coil 20. The depth of the mounting area (the axial dimension of the mounting groove 111) is greater than or equal to the thickness of the superconducting coil 20 (the axial dimension of the superconducting coil 20).

[0045] When the superconducting coil 20 is in operation, it also generates a radial force. Therefore, a support plate 112 is provided so that when the superconducting coil 20 generates a radial force, the support plate 112 generates a reaction force to the superconducting coil 20, thereby supporting the superconducting coil 20. Furthermore, the superconducting coil 20 can be entirely located within the installation area, so that the edge of the superconducting coil 20 can fully contact the support plate 112 in the thickness direction, thereby obtaining stable support from the support plate 112.

[0046] The mounting groove 111 has an arc-shaped edge, the same curvature as the mounting base plate 12, so that the edge of the mounting base plate 12 can fit against the arc-shaped inner wall of the mounting groove 111. The support plate 112 is an arc-shaped plate, the same curvature as the mounting groove 111, so that the edge of the superconducting coil 20 can fit against the concave arc surface of the support plate 112, thereby supporting the superconducting coil 20. Four support plates 112 can be provided, concentrically arranged and evenly spaced along the circumference of the mounting groove 111.

[0047] In some embodiments, the main frame 11 also has a liquid nitrogen inlet (not shown in the figure), a liquid nitrogen outlet (not shown in the figure), and a first air extraction port (not shown in the figure) connected to the cooling chamber 116. Liquid nitrogen can be introduced into the cooling chamber 116 through the liquid nitrogen inlet and liquid nitrogen or a mixture of liquid nitrogen and nitrogen can be discharged through the liquid nitrogen outlet. Air can be discharged through the first air extraction port to form a vacuum state.

[0048] The first evacuation port is used to connect to a vacuum pump to evacuate the cooling chamber 116 to a vacuum state, so as to facilitate the introduction of liquid nitrogen and avoid the gas in the cooling chamber 116 from conducting heat and affecting the cooling efficiency. The liquid nitrogen inlet is used to connect to a liquid nitrogen storage tank to introduce liquid nitrogen into the cooling chamber 116. The liquid nitrogen outlet is used to connect to a liquid nitrogen heat exchanger and a liquid nitrogen pump to discharge liquid nitrogen or a mixture of liquid nitrogen and nitrogen gas. The temperature of liquid nitrogen is very low. Combined with the refrigerator, the simultaneous conduction cooling can quickly reduce the temperature of the superconducting coil frame 10 to the liquid nitrogen temperature in advance.

[0049] The liquid nitrogen inlet, the first evacuation port, and the liquid nitrogen outlet can be located at suitable positions on the main frame 11, such as the top. The liquid nitrogen storage tank is connected to the liquid nitrogen inlet via a liquid nitrogen input pipe and to the liquid nitrogen outlet via a liquid nitrogen output pipe. The liquid nitrogen output pipe is also equipped with a liquid nitrogen pump and a liquid nitrogen heat exchanger. The liquid nitrogen pump pumps liquid nitrogen into and out of the cooling chamber 116, creating a circulation of liquid nitrogen within the cooling chamber 116. Both the liquid nitrogen input and output pipes are sealed and pass through the Dewar 40 and the cold shield 30 before connecting to the cooling chamber 116. This sealing prevents air leakage from the Dewar 40 and heat leakage from the cold shield 30. Additionally, vacuum valves are installed on the liquid nitrogen input and output pipes, replacing the vacuum pump to create a vacuum state within the cooling chamber 116.

[0050] The superconducting magnet includes a superconducting coil 20 and the superconducting coil frame 10 described above, with the superconducting coil 20 mounted in the mounting slot 111.

[0051] Please refer to Figure 3 This is a perspective view of the superconducting magnet provided in the embodiments of this application, in which the cold screen 30 and Dewar 40 are not shown.

[0052] It should be noted that the superconducting magnet includes the superconducting coil frame 10, and thus includes all the advantages of the superconducting coil frame 10 mentioned above, which will not be repeated here.

[0053] The superconducting coil 20 includes a double-pancake coil with multiple layers stacked together.

[0054] In addition, the superconducting magnet also includes multiple cooling plates 51 and cooling connecting plates 52. The shape and size of the cooling plates 51 are the same as the shape and size of the plate 121 of the mounting base plate 12. Each cooling plate 51 corresponds to a superconducting coil 20 and is attached to the side of the superconducting coil 20 away from the mounting base plate 12. It is used to fix multiple superconducting coils 20. A cooling connecting plate 52 is connected between every two adjacent cooling plates 51. The temperature of one superconducting coil 20 can be transferred to its corresponding cooling plate 51, and then transferred to another adjacent cooling plate 51 through the cooling connecting plate 52 connected to the cooling plate 51. Then, it is transferred to its corresponding superconducting coil 20 through the other cooling plate 51, which can accelerate the cooling of all superconducting coils 20 to the same temperature.

[0055] Please refer to Figure 4 , Figure 4 This is a longitudinal cross-sectional view of the superconducting magnet provided in an embodiment of this application.

[0056] In some embodiments, the superconducting magnet further includes a cold screen 30 and a Dewar 40. The cold screen 30 is hollow and forms a first mounting cavity 31. The superconducting coil frame 10 is disposed in the first mounting cavity 31. The Dewar 40 is hollow and forms a second mounting cavity 45. The Dewar 40 has a second evacuation port (not shown in the figure) communicating with the second mounting cavity 45. The second mounting cavity 45 can be made into a vacuum state through the second evacuation port. The cold screen 30 is disposed in the second mounting cavity 45.

[0057] The cooling screen 30 isolates the superconducting coil 20 from the external temperature, keeping it in a suitable low-temperature environment. The second evacuation port is used to connect to a vacuum pump and can be connected to the same vacuum pump as the first evacuation port of the main frame 11. The second mounting cavity 45 of the Dewar 40 can form a vacuum state through the second evacuation port, preventing the gas in the second mounting cavity 45 from transferring the external temperature of the Dewar 40 to the cooling screen 30, thereby avoiding affecting the low-temperature environment of the superconducting coil 20.

[0058] The second vent can be located in a suitable position on the Dewar 40, such as the top or side, not shown in the figure. Figure 4As shown, the Dewar 40 includes an inner cylinder 41, an outer cylinder 42, and an upper cover plate 43 and a lower cover plate 44 connecting the inner cylinder 41 and the outer cylinder 42. The inner cylinder 41 and the outer cylinder 42 are cylindrical structures with different diameters. The upper cover plate 43 is fixed to the top of the inner cylinder 41 and the outer cylinder 42, and the lower cover plate 44 is fixed to the bottom of the inner cylinder 41 and the outer cylinder 42. The inner cylinder 41, the outer cylinder 42, the upper cover plate 43, and the lower cover plate 44 together form a second mounting cavity 45. The material of the inner cylinder 41 can be a non-magnetic material such as austenitic stainless steel, while the materials of the outer cylinder 42, the upper cover plate 43, and the lower cover plate 44 can all be magnetic materials such as carbon steel, forming a magnetic shielding layer. This arrangement can prevent the magnetic field of the superconducting magnet from affecting people or other equipment, and can also strengthen the magnetic field strength at the center of the superconducting magnet. The thickness of the outer cylinder 42, the upper cover plate 43 and the lower cover plate 44 can be 20mm to 50mm, preferably 20mm to 30mm. This thickness can reduce the mass of the superconducting magnet while meeting the requirements of the leakage magnetic field.

[0059] In some embodiments, two chillers can be configured and fixed to the upper surface of the Dewar 40. One chiller is used to cool two superconducting coils 20, and the other chiller is used to cool two other superconducting coils 20, thereby balancing the temperature of the superconducting coil frame 10, the cold screen 30, and the superconducting coils 20, reducing the temperature gradient, and meeting the operating temperature requirements of the superconducting coils 20. Furthermore, the chillers can be GM chillers. The primary cold head of the chiller can penetrate the Dewar 40 and be connected to the cold screen 30 via copper heat-conducting plates to cool the cold screen 30 to a certain temperature. The secondary cold head of the chiller can penetrate the cold screen 30 and be connected to the superconducting coil frame 10 via copper heat-conducting plates.

[0060] Please refer to Figure 3 In some embodiments, the superconducting magnet further includes a first tie rod (not shown in the figure), a second tie rod 61, and a third tie rod 62. One end of the first tie rod is connected to the lower frame 114 of the main frame 11 and passes through the cold screen 30, while the other end is connected to the top inner wall of the Dewar 40. One end of the second tie rod 61 is connected to the upper frame 113 of the main frame 11 and passes through the cold screen 30, while the other end is connected to the bottom inner wall of the Dewar 40. One end of the third tie rod 62 is connected to the connecting post 115 of the main frame 11 and passes through the cold screen 30, while the other end is connected to the side inner wall of the Dewar 40.

[0061] The first tie rod, the second tie rod 61, and the third tie rod 62 are used to support the superconducting coil frame 10. Each of these can be one, a combination of two, or a combination of three of the following: epoxy straight tie rod, racetrack-shaped epoxy tie rod, and titanium alloy straight tie rod. A disc spring can be installed at the connection between the third tie rod 62 and the Dewar 40 to compensate for the cold shrinkage deformation of the tie rod and other components through the elastic deformation of the disc spring. The third tie rod 62 and the Dewar 40 can be connected by threads, allowing for adjustment of the concentricity and magnetic field distribution of the superconducting magnet by screwing.

[0062] A cooling method for superconducting magnets, applied to the aforementioned superconducting magnets, includes the following steps:

[0063] S01. Evacuate the second mounting cavity 45 in the Dewar 40 and the cooling cavity 116 in the main frame 11 to a vacuum state.

[0064] S02. Introduce liquid nitrogen into the cooling chamber 116 and start the refrigeration unit at the same time;

[0065] S03. Pre-cooling begins. The refrigerator cools the cold screen 30 and the superconducting coil frame 10 through conduction cooling. The liquid nitrogen in the cooling chamber 116 cools the superconducting coil frame 10 through heat exchange until the temperature of the first mounting chamber 31, the superconducting coil frame 10 and the superconducting coil 20 are the same as the temperature of the liquid nitrogen in the cooling chamber 116, i.e. -196℃.

[0066] S04. Extract the liquid nitrogen from the cooling chamber 116 and restore the cooling chamber 116 to a vacuum state;

[0067] S05. The refrigerator continues to cool the cold shield 30 and the superconducting coil frame 10 through conductive cooling until the temperature of the first mounting cavity 31, the superconducting coil frame 10, and the superconducting coil 20 reaches the operating temperature of the superconducting coil 20, so that the superconducting coil 20 is in a superconducting state. After the temperature stabilizes at this operating temperature, it is energized. If the superconducting coil 20 is a high-temperature superconducting coil, its operating temperature can be approximately -253℃; if the superconducting coil 20 is a low-temperature superconducting coil, its operating temperature can be approximately -268.95℃.

[0068] In step S01, the gas in the second mounting cavity 45 is extracted through the second evacuation port on the Dewar 40 to prevent the gas in the second mounting cavity 45 from transferring heat from the outside of the second mounting cavity 45 to the cold screen 30, thereby avoiding affecting the low-temperature environment of the superconducting coil 20. The gas in the cooling cavity 116 is extracted through the first evacuation port on the main frame 11 to prevent the gas in the cooling cavity 116 from slowing down the subsequent cooling rate, and to facilitate the subsequent introduction of liquid nitrogen. The vacuum state of the second mounting cavity 45 and the cooling cavity 116 can reduce heat conduction and convection, and improve cooling efficiency.

[0069] In step S02, the liquid nitrogen itself has a low temperature, which can reduce the temperature inside the cooling chamber 116 and achieve pre-cooling. The liquid nitrogen has a large contact area with the cavity wall of the cooling chamber 116, which can achieve rapid pre-cooling of the superconducting coil 20. In conjunction with the refrigerator, it can further improve the cooling efficiency.

[0070] In step S03, the temperature of the superconducting coil skeleton 10 and the superconducting coil 20 can be rapidly reduced by the secondary cooling of the refrigerator and the liquid nitrogen cooling, thus achieving pre-cooling.

[0071] In step S04, after the superconducting coil skeleton 10 and the superconducting coil 20 are cooled to the temperature of liquid nitrogen, the liquid nitrogen is extracted from the cooling chamber 116 until the cooling chamber 116 is restored to a vacuum state, so that the temperature in the cooling chamber 116 is kept in a low range, and the temperature of the heated liquid nitrogen and the temperature of the vaporized nitrogen gas are prevented from being transferred back to the superconducting coil 20, thereby minimizing the cooling time of the superconducting coil 20.

[0072] In step S05, the temperature of the first mounting cavity 31, the superconducting coil skeleton 10, and the superconducting coil 20 is further reduced to complete the step cooling. That is, the first cooling is achieved by liquid nitrogen and a refrigerator, and the second cooling is achieved by the refrigerator alone.

[0073] This application employs a method of simultaneous pre-cooling with vacuuming, liquid nitrogen, and a refrigerator, followed by extraction of liquid nitrogen and continued cooling with the refrigerator. This method can rapidly reduce the superconducting coil 20 to its operating temperature. Compared to the prior art which only uses liquid nitrogen for cooling, this application achieves a lower and more reliable cooling temperature and higher cooling efficiency.

[0074] In the description of this application, it should be understood that the terms "center", "depth", "thickness", "inner", "outer", "top", "bottom", "upper", "lower", "horizontal", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0075] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0076] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "fixation," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between the components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the connection within two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0077] In this application, the term "some embodiments," etc., refers to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0078] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A superconducting coil frame, characterized in that, include: The main frame is formed in the shape of a ring and has multiple mounting slots for accommodating multiple superconducting coils in a one-to-one correspondence. The multiple mounting slots are arranged at intervals along the circumference of the main frame. The main frame is hollow and forms a cooling cavity. as well as The mounting base plates are configured to be one-to-one correspondingly attached to the bottom of the mounting groove. At least two mounting base plates are arranged opposite each other to form a group, and at least two groups of mounting base plates are provided. The angle α between the central axis of one group of oppositely arranged mounting base plates and the central axis of the adjacent group of oppositely arranged mounting base plates is 66°. The mounting base plates are used to attach and connect the superconducting coil, so as to provide axial support force for the superconducting coil together with the main frame and transfer the temperature of the cooling cavity to the superconducting coil.

2. The superconducting coil frame according to claim 1, characterized in that, The mounting slot is located on the inner side of the main frame.

3. The superconducting coil frame according to claim 2, characterized in that, The mounting slots are configured as four, with each pair of mounting slots forming a group. The two groups of mounting slots are symmetrically arranged, and the central angle of the mounting base plate on each of the two mounting slots in each group is α.

4. The superconducting coil frame according to claim 2, characterized in that, The centers of all the mounting base plates are located in the same horizontal plane.

5. The superconducting coil frame according to claim 2, characterized in that, The mounting base plate includes a plate body formed in the shape of a disc, a plurality of reinforcing ribs disposed on the plate body, and a connecting plate connected to the reinforcing ribs. The reinforcing ribs are disposed on the side of the plate body away from the center of the main frame body. The plurality of reinforcing ribs are arranged at intervals along the circumference of the plate body. The reinforcing ribs are connected to the main frame body through the connecting plate.

6. The superconducting coil frame according to claim 2, characterized in that, The main frame includes a support plate disposed on the edge of the mounting groove. The support plate and the mounting base plate cooperate to form a mounting area for mounting the superconducting coil. The depth of the mounting area is greater than or equal to the thickness of the superconducting coil.

7. The superconducting coil frame according to any one of claims 1 to 6, characterized in that, The main frame also has a liquid nitrogen inlet, a liquid nitrogen outlet and a first air extraction port connected to the cooling chamber. Liquid nitrogen can be introduced into the cooling chamber through the liquid nitrogen inlet and liquid nitrogen or a mixture of liquid nitrogen and nitrogen can be discharged through the liquid nitrogen outlet. Air can be discharged through the first air extraction port to form a vacuum state.

8. A superconducting magnet, characterized in that, include: Superconducting coils; as well as The superconducting coil frame according to any one of claims 1 to 7, wherein the superconducting coil is mounted to the mounting slot.

9. The superconducting magnet according to claim 8, characterized in that, The superconducting magnet also includes a cold screen and a Dewar. The cold screen is hollow and forms a first mounting cavity. The superconducting coil frame is disposed in the first mounting cavity. The Dewar is hollow and forms a second mounting cavity. The Dewar has a second evacuation port connected to the second mounting cavity. The second mounting cavity can be made into a vacuum state through the second evacuation port. The cold screen is disposed in the second mounting cavity.

10. A cooling method for a superconducting magnet, characterized in that, The application to the superconducting magnet according to claim 9 includes the following steps: The second mounting cavity inside the Dewar and the cooling cavity inside the main frame are evacuated to a vacuum state; Liquid nitrogen is introduced into the cooling chamber, and the refrigeration unit is started simultaneously; Pre-cooling begins, with the refrigerator cooling the cold screen and the superconducting coil frame via conductive cooling, and the liquid nitrogen in the cooling chamber cooling the superconducting coil frame via heat exchange, until the temperatures of the first mounting cavity, the superconducting coil frame, and the superconducting coil are all the same as the temperature of the liquid nitrogen in the cooling chamber. Extract the liquid nitrogen from the cooling chamber and restore the cooling chamber to a vacuum state; The refrigerator continues to cool the cold screen and the superconducting coil frame through conductive cooling until the temperature of the first mounting cavity, the superconducting coil frame, and the superconducting coil reaches the operating temperature of the superconducting coil.

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