Compact superconducting coil heat transfer structure and liquid-helium-free superconducting magnet

Abstract

This invention belongs to the field of nuclear magnetic resonance technology and discloses a compact superconducting coil heat transfer structure and a liquid helium-free superconducting magnet. The compact superconducting coil heat transfer structure, applied to a liquid helium-free superconducting magnet, includes a tubular superconducting coil winding frame. A flattened superconducting coil assembly is wound around the outer surface of the superconducting coil winding frame via grooves. A heat transfer plate is provided on the outer side of the superconducting coil winding frame, and an end-face heat-conducting plate is provided at each end of the superconducting coil winding frame. Each end of the heat transfer plate is connected to the corresponding end-face heat-conducting plate, and a heat transfer metal plate is connected to both end-face heat-conducting plates. The heat transfer metal plate is in contact with the superconducting coil assembly to form a closed heat transfer loop. This invention has a compact overall structure and, through the heat transfer plates, significantly reduces the risk of excitation quench, improving the ease of use and stability of the equipment.

Description

Technical Field

[0001] This invention belongs to the field of nuclear magnetic resonance technology, specifically relating to a compact superconducting coil heat transfer structure and a liquid helium-free superconducting magnet. Background Technology

[0002] Due to the scarcity of liquid helium resources in my country, liquid helium-free superconducting magnet systems have begun to develop rapidly. The difference between liquid helium-free and liquid helium-based superconducting magnet systems lies in the cooling method of the superconducting magnet. Liquid helium-based systems have a liquid helium tank to hold liquid helium, which is then injected to control the ambient temperature of the superconducting coil. Liquid helium-free systems, on the other hand, use contact heat conduction, with a metal strip wound around the outside of the superconducting coil for heat conduction. The end of the metal strip is connected to the second-stage cold head of the refrigerator. Compared to liquid helium-based systems, liquid helium-free superconducting magnet systems have lower production costs and require less liquid helium, representing the future trend in superconducting magnet systems.

[0003] Traditional liquid helium-free superconducting magnets rely on cryogenic refrigerators to lower the entire superconducting coil to the required cryogenic state. The structure connecting the cryogenic refrigerator and the superconducting coil (including the coil frame) is often made of high-purity oxygen-free copper. To ensure that the cooling meets the design requirements, a certain degree of redundancy is adopted, that is, a considerable number of oxygen-free copper plates are used to cover the surface of the superconducting coil and frame as much as possible. This can maximize the stability of the cryogenic system of the superconducting magnet. However, excessive use of oxygen-free copper will greatly increase the overall weight, volume and cost. Moreover, thicker oxygen-free copper plates are used as the main heat transfer structure, while other sub-components, such as quench protection units, excitation and power-on units, on / off switches, and vacuum suction devices, are distributed in a relatively large space.

[0004] Currently, if patients need MRI scans of their joints, most must schedule a traditional whole-body MRI, which involves long waiting times, uncomfortable scanning procedures, and cumbersome steps requiring visits to large hospitals. Given this market situation, there is a need to design a compact, lightweight MRI device that can be deployed in community hospitals at all levels, as well as small county and township health institutions, with low practical requirements.

[0005] To achieve the above application scenarios and design requirements, a novel liquid helium-free superconducting magnet heat transfer structure needs to be proposed, and the space of the superconducting heat transfer structure in the axial and radial directions should be minimized as much as possible. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a compact superconducting coil heat transfer structure for a liquid helium superconducting magnet and a liquid helium-free superconducting magnet, so as to reduce its space occupation in the axial and radial directions from the perspective of heat transfer structure.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] On one hand, a compact superconducting coil heat transfer structure is provided for use in liquid helium-free superconducting magnets. It includes a tubular superconducting coil winding frame, with a flat superconducting coil assembly wound around its outer surface via slots. A heat transfer plate is provided on the outer side of the superconducting coil winding frame, and an end-face heat-conducting plate is provided at each end of the frame. The two ends of the heat transfer plate are connected to the corresponding end-face heat-conducting plates. A heat transfer metal plate is also connected to the end-face heat-conducting plates at both ends, and the heat transfer metal plate is in contact with the superconducting coil assembly to form a closed heat transfer loop.

[0009] The heat transfer plate is provided with a secondary heat transfer conversion plate on its outer side. The secondary heat transfer conversion plate is provided with a secondary heat connection component for the refrigerator. The secondary heat connection component for the refrigerator connects the refrigerator and the superconducting coil assembly.

[0010] In one possible implementation, the edge of the end face heat-conducting plate has a bent connecting portion that overlaps the outside of the heat transfer plate.

[0011] In one possible implementation, the contact surface between the connection and the heat transfer plate is coated with a first silicone grease coating to reduce thermal resistance.

[0012] In one possible implementation, the heat transfer metal plate is formed by bending or stamping to create multiple embedded portions that extend into the grooves and fit against the superconducting coil assembly.

[0013] In a possible implementation, the embedded portion is provided with a second silicone grease coating or an epoxy coating.

[0014] In one possible implementation, the refrigeration unit has two secondary thermal connectors that are symmetrically fixed to both sides of the secondary heat transfer conversion plate by fasteners, and the upper ends of the two refrigeration unit secondary thermal connectors are simultaneously connected to the lower connecting plate of the secondary cold head of the refrigeration unit by fasteners.

[0015] In a possible implementation, the secondary heat transfer conversion plate is further provided with an excitation and power supply unit, one end of which is connected to the HTS power supply lead and the other end is coupled to the superconducting wire.

[0016] In one possible implementation, the heat transfer plate is further provided with an on / off switch unit adjacent to the secondary heat transfer conversion plate. The on / off switch unit is coupled to the positive and negative poles of the superconducting coil and the excitation and power-on unit through a junction box.

[0017] In a possible implementation, the heat transfer plate is further provided with a quench protection unit connected to the end face heat conduction plate;

[0018] The quench protection unit includes a metal mounting plate, an insulating sleeve rod for conductive plates, conductive metal plates, a low-temperature diode, and an insulating base plate. The insulating base plate is connected to the end face heat-conducting plate through the metal mounting plate. Multiple parallel conductive metal plates are connected to the insulating base plate through insulating fixing components. A low-temperature diode is provided between adjacent conductive metal plates.

[0019] On the other hand, a liquid helium-free superconducting magnet is also provided, characterized in that it includes a compact superconducting coil heat transfer structure as described in any of the above technical solutions.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The compact superconducting coil heat transfer structure of the present invention has a compact overall structure and can form a compact closed heat transfer loop with the superconducting coil through the heat transfer plate, end face heat conduction plate and heat transfer metal plate. This can result in high heat transfer efficiency and help control the temperature difference between the secondary cold head of the refrigerator and the highest temperature point (farthest end) of the superconducting coil within 0.1K, which greatly reduces the risk of excitation failure and improves the ease of use and stability of the equipment.

[0022] Moreover, the flexible connection structure has been modified, and instead of using copper braided strips, copper plates are bent to form the secondary thermal connection of the refrigeration unit. This can meet the mechanical performance of the superconducting coil and the low-temperature shrinkage performance of the cold head. This maximizes the heat transfer cross-sectional area of ​​the secondary cold head thermal connection, and the requirements for copper material can be appropriately relaxed, reducing costs while fully meeting design requirements.

[0023] Meanwhile, the compact superconducting coil heat transfer structure, along with the optimized design of each part, significantly reduces costs and further decreases the weight and space of the entire magnet. This greatly reduces the requirements for installation conditions and site conditions. At the same time, the liquid helium-free design structure can also meet the needs of many medical institutions that do not have a superheated helium recovery system. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of a compact superconducting coil heat transfer structure according to an embodiment of this application;

[0025] Figure 2 This is a schematic diagram of the arrangement of heat transfer metal plates in a compact superconducting coil heat transfer structure according to an embodiment of this application.

[0026] Figure 3 This is a schematic diagram of the connection structure of a secondary thermal connector for a refrigerator, which is a compact superconducting coil heat transfer structure according to an embodiment of this application.

[0027] Figure 4 This is a schematic diagram of the quench protection unit of a compact superconducting coil heat transfer structure according to an embodiment of this application;

[0028] Figure 5 This is a side view of the vacuum suction structure of a compact superconducting coil heat transfer structure according to an embodiment of this application.

[0029] In the diagram: 1-End face heat-conducting plate; 2-Superconducting coil winding frame; 3-Superconducting coil assembly; 4-Heat transfer plate; 5-Quake protection unit; 6-Secondary thermal connection of the refrigerator; 7-Secondary heat transfer conversion plate; 8-Excitation and power-on unit; 9-On / off closing switch unit; 10-Vacuum suction unit; 11-Heat transfer copper plate; 12-Mounting aluminum plate; 13-Conduction plate insulating sleeve rod; 14-Conduction copper plate; 15-Low temperature diode; 16-Insulating base plate; 17-Secondary cold head lower connection plate; 18-Screw; 19-Mounting base; 20-Base plate; 21-Mounting front panel; 22-Surface pressure plate. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Traditional cooling of liquid helium-free superconducting magnets relies on cryogenic refrigerators to lower the entire superconducting coil to the required cryogenic state. The structure connecting the cryogenic refrigerator and the superconducting coil (including the coil frame) often uses high-purity oxygen-free copper. To ensure the cooling meets design requirements, a certain degree of redundancy is employed, meaning a considerable number of oxygen-free copper plates are used to cover the surface of the superconducting coil and frame as much as possible. This maximizes the stability of the superconducting magnet cryogenic system. However, excessive use of oxygen-free copper significantly increases the overall weight and cost. Traditional methods use thicker oxygen-free copper plates as the primary heat transfer structure, while distributing other sub-components, such as quench protection units, excitation and power-on units, on / off switches, and vacuum suction devices, within a relatively large space.

[0032] Currently, most patients requiring MRI scans of joints need to schedule traditional whole-body MRI scans, which involve long waiting times, uncomfortable scanning procedures, and cumbersome processes requiring visits to large hospitals. Based on this market situation, a compact and lightweight magnet was designed for deployment in community hospitals and small township health centers at all levels. Considering the environmental, site, and location limitations of lower-level health institutions, it operates using a liquid helium-free superconducting magnet. During normal operation, it requires no liquid helium refilling and no periodic checks of pressure or helium consumption, simplifying maintenance and installation. Due to its lightweight structure, it does not have special requirements regarding site load-bearing capacity. The load-bearing design of most civil buildings can accommodate the magnet.

[0033] At the same time, the needs of customers must be considered. As a core component of the MRI system, the superconducting magnet, in addition to structural and weight limitations, also needs to control the overall cost in order to provide high-quality and affordable joint imaging services to a wide range of patients.

[0034] To meet the aforementioned application scenarios and design requirements, a novel liquid helium-free superconducting magnet layout structure needs to be proposed, minimizing the space required for the superconducting coil in both the axial and radial directions. This necessitates a redesign of components mounted on the cryogenic structure, including the cryogenic heat transfer structure, cold head thermal connection assembly, vacuum suction device, quench protection device, on / off switch, and excitation and power supply unit, while simultaneously optimizing their layout in conjunction with the cryogenic structure itself.

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] Please refer to Figure 1-5 As shown, an embodiment of this application provides a compact superconducting coil heat transfer structure for use in liquid helium-free superconducting magnets. It includes a tubular superconducting coil winding frame 2, with a flattened superconducting coil assembly 3 wound around its outer surface via grooves. A heat transfer plate 4 is provided on the outer side of the superconducting coil winding frame 2. An end-face heat-conducting plate 1 is provided at each end of the superconducting coil winding frame 2, with each end of the heat transfer plate 4 connected to the corresponding end-face heat-conducting plate 1. A heat transfer metal plate is also connected to the end-face heat-conducting plates 1 at both ends, and the heat transfer metal plate is in contact with the superconducting coil assembly 3 to form a closed heat transfer loop. A secondary heat transfer conversion plate 7 is provided on the outer side of the heat transfer plate 4, and a secondary thermal connector 6 for a refrigerator is provided on the secondary heat transfer conversion plate 7, connecting the refrigerator and the superconducting coil assembly 3.

[0037] This technical solution results in a compact overall structure. The heat transfer plate 4, the end face heat conduction plate 1, and the heat transfer metal plate can form a compact closed heat transfer loop with the superconducting coil, which can achieve high heat transfer efficiency. This helps to control the temperature difference between the secondary cold head of the refrigerator and the highest temperature point (farthest end) of the superconducting coil within 0.1K, greatly reducing the risk of excitation failure and improving the ease of use and stability of the equipment.

[0038] In one embodiment, the edge of the end face heat-conducting plate 1 has a bent connecting portion that overlaps the outside of the heat transfer plate 4.

[0039] The connection formed by bending allows the end face heat-conducting plate 1 to come into closer contact with the heat transfer plate 4. The overlapping method can obtain a larger contact area and improve the heat transfer effect.

[0040] Furthermore, to improve the thermal resistance of the contact surface, the contact surface between the connecting part and the heat transfer plate 4 is coated with a first silicone grease coating to reduce thermal resistance. This further reduces the temperature difference between the heat transfer surface and the secondary cold head of the cryogenic refrigerator.

[0041] In embodiments of this application, the heat transfer metal plate is formed by bending or stamping to create a plurality of embedded portions that extend into the groove and fit against the superconducting coil assembly 3.

[0042] The heat transfer metal plate can be embedded in the heat transfer metal plate and fit into the superconducting coil group 3, which makes the superconducting coil group 3 more stable in the wire slot and can also ensure the heat transfer performance of the coil in the axial direction.

[0043] Furthermore, the embedded portion is provided with a second silicone grease coating or an epoxy coating. The second silicone grease coating or epoxy coating can reduce thermal resistance and improve heat transfer efficiency.

[0044] In the specific implementation process, the heat transfer metal plate is a heat transfer copper plate 11, which is made of 2mm thick copper plate bent and stamped to form an embedded part. During installation, it is first subjected to vacuum heat treatment to ensure that it fits in close contact with the frame and coil surface. At the same time, multiple sets of different surface pressure plates 22 can be set to press the heat transfer copper plate 11 tightly.

[0045] In a preferred embodiment of the secondary thermal connector 6 of the refrigeration unit, two secondary thermal connectors 6 are provided and are symmetrically fixedly connected to both sides of the secondary heat transfer conversion plate 7 by fasteners. The upper ends of the two secondary thermal connectors 6 are simultaneously connected to the lower connecting plate 17 of the secondary cold head of the refrigeration unit by fasteners.

[0046] The secondary thermal connector 6 of the refrigerator plays a crucial role in connecting the refrigeration unit to the overall superconducting coil. It also features a completely new design, abandoning the traditional structure of pressing or welding copper braided strips without liquid helium magnets. Instead, it uses an 8mm copper plate that is bent to provide sufficient heat transfer cross-sectional area. Simultaneously, the calculated and optimized bending structure effectively balances low-temperature stress, ensuring axial low-temperature contraction during refrigerator operation and guaranteeing coil stress balance and normal refrigerator operation. Furthermore, this structure of the secondary thermal connector 6 is highly beneficial for balancing the low-temperature stress of the superconducting coil and the low-temperature axial tensile force of the cold head. Because it is made of solid copper plate, it provides a sufficiently large heat transfer cross-sectional area while reducing installation space. Of course, due to its rigid structure, a dedicated secondary heat transfer conversion plate 7 provides additional installation and operation space.

[0047] In the embodiments of this application, the secondary heat transfer conversion plate 7 may also be provided with an excitation and power supply unit 8, one end of which is connected to the HTS power supply lead and the other end is coupled to the superconducting wire.

[0048] Furthermore, the heat transfer plate 4 is also equipped with an on / off switch unit 9 adjacent to the secondary heat transfer conversion plate 7. The on / off switch unit 9 is coupled to the positive and negative poles of the superconducting coil and the excitation and power-on unit 8 through a junction box. The on / off switch unit 9 provides on / off control for the closed coil of the superconducting coil. It is coupled to the positive and negative poles of the superconducting coil and the excitation and power-on unit 8 through the junction box, and is tightly connected to the heat transfer plate 4 by high-temperature soldering.

[0049] In the embodiments of this application, the heat transfer plate 4 is further provided with a quench protection unit 5 connected to the end face heat conduction plate 1; the quench protection unit 5 includes a metal mounting plate, a conductive plate insulating sleeve 13, a conductive metal plate, a low temperature diode 15, and an insulating base plate 16; the insulating base plate 16 is connected to the end face heat conduction plate 1 through the metal mounting plate, and multiple parallel conductive metal plates are connected on the insulating base plate 16 through insulating fixing components, and a low temperature diode 15 is provided between adjacent conductive metal plates.

[0050] The quench protection unit 5 is assembled using an ultra-thin low-temperature diode 15. The design considers insulation and current-carrying performance while minimizing the overall structural dimensions. Specifically, the metal mounting plate is made of aluminum, the conductive plate insulating sleeve 13 isolates the positive and negative electrodes, and the conductive metal plate is preferably a conductive copper plate 14, made of 5mm copper, providing a current-carrying circuit for the diode. The low-temperature diode 15 is an ultra-thin type. Due to the extremely compact installation space, the insulating base plate 16 forms an insulating structure between the mounting metal plate and the heat transfer structure.

[0051] In other embodiments, a vacuum suction unit 10 may be provided to provide degassing operation inside the vacuum Dewar (not shown in the figure), ensuring that the internal vacuum is maintained. It also employs a compact design located at the top. Specifically, the vacuum suction unit 10 may include a mounting base 19 connected to the secondary heat transfer conversion plate 7. A base plate 20 is connected to the mounting base 19, and a front mounting panel 21 is located on the front side of the base plate 20. All of these components are made of bent aluminum alloy to ensure the stability of the heat transfer structure while minimizing the vertical height. Their thickness has also been optimized to fit into confined installation spaces.

[0052] Embodiments of this application also provide a liquid helium-free superconducting magnet, including a compact superconducting coil heat transfer structure as described in any of the above technical solutions.

[0053] Preferred embodiment:

[0054] Please refer to Figure 1-5As shown, a compact superconducting coil heat transfer structure is used in liquid helium-free superconducting magnets, including a superconducting coil winding frame 2, a superconducting coil assembly 3, a heat transfer plate 4, an end face heat-conducting plate 1, a heat transfer metal plate, a secondary heat transfer conversion plate 7, a secondary thermal connection component of a refrigerator 6, a quench protection unit 5, an excitation and energizing unit 8, an on / off closing switch unit 9, and a vacuum suction device, etc.

[0055] The end-face heat-conducting plate 1 is a component in the superconducting magnet heat transfer structure used for end-face heat conduction. It is arranged at both ends of the frame and connected to the top heat transfer plate 4. The contact surface between the end-face of the plate and the heat transfer plate 4 is coated with a low-temperature silicone grease layer to improve the thermal resistance of the contact surface and further reduce the temperature difference between the plate and the secondary cold head of the cryogenic refrigerator. The end-face heat-conducting plate 1 is made of 2mm bright thin copper plate by bending, which is lightweight and does not occupy external space in the axial direction of the superconducting coil, thus reducing the installation space of the external cold shield and vacuum Dewar shell.

[0056] The superconducting coil winding skeleton 2 is entirely machined from thick-walled stainless steel tubing, making it significantly thinner in the radial direction than traditional superconducting coil skeletons, with a maximum thickness of less than 30mm. Optimized coil design eliminates the need for the external shielding reverse coil of traditional MRI superconducting magnets, thus greatly saving radial space. Similarly, it allows for sufficient space for the cold screen and vacuum Dewar. Furthermore, the use of profiled thick-walled stainless steel tubing significantly reduces processing time and costs, while also ensuring excellent mechanical and cryogenic performance of the skeleton.

[0057] Based on the description of the functions of the two components mentioned above, the axial and radial space optimization measures for the entire superconducting magnet cryogenic structure have been preliminarily completed.

[0058] Superconducting coil group 3 is a collective term for a group of superconducting coils. Superconducting coil group 3 uses low-temperature niobium-titanium superconducting wires uniformly and densely distributed within the precision-machined grooves of the frame. Considering low-temperature performance, each coil is impregnated with low-temperature epoxy resin, forming a low-temperature epoxy resin layer on the coil surface. Considering the overall compact design requirements and cost requirements, and while meeting the overall magnetic field distribution uniformity requirements, new constraints are imposed on the coils, including the coil volume V. coil The minimum value is taken, that is, the overall coil structure is flat, and the external shielding coil design of traditional MRI superconducting magnets is eliminated.

[0059] The heat transfer plate 4 is tightly connected to the secondary heat transfer conversion plate 7 and the end face heat conduction plate 1. It also houses a quench protection unit 5, an excitation and power supply unit 8, an on / off switch unit 9, and a small vacuum suction device. The heat transfer plate 4 ensures the low-temperature stability of the superconducting coil and its auxiliary equipment. It is the thickest copper plate component used in all low-temperature heat transfer structures, requiring approximately 8mm of high-purity oxygen-free plate for fabrication.

[0060] The quench protection unit 5 is assembled using ultra-thin low-temperature diodes 15. Its design considers insulation and current conduction performance while minimizing the overall structural dimensions. In a preferred embodiment of the quench protection unit 5, it includes an aluminum plate, a conductive plate insulating sleeve 13, a conductive metal plate, a low-temperature diode 15, and an insulating base plate 16. The insulating base plate 16 is connected to the end-face heat-conducting plate 1 via a metal mounting plate. Multiple parallel conductive metal plates are connected to the insulating base plate 16 via insulating fixing components, and low-temperature diodes 15 are positioned between adjacent conductive metal plates. (Please refer to...) Figure 2 As shown, the mounting aluminum plate 12 is installed at the bottom; the conductive plate insulating sleeve 13 is used to isolate the positive and negative electrodes; the conductive metal plate is a conductive copper plate 14, which is made of 5mm copper plate and provides a power-carrying circuit for the diode; the low temperature diode 15 is an ultra-thin low temperature diode 15; the insulating base plate 16, due to the extremely compact installation space, ensures that the mounting aluminum plate 12 is insulated from the heat transfer structure.

[0061] The secondary thermal connector 6 of the refrigerator plays a crucial role in connecting the refrigerator to the overall superconducting coil. It also features a completely new design, abandoning the traditional structure of pressing or welding copper braided strips without liquid helium magnets. Instead, it uses an 8mm copper plate through bending, providing sufficient heat transfer cross-sectional area. Simultaneously, the calculated and optimized bending structure effectively balances low-temperature stress, ensuring axial low-temperature contraction during refrigerator operation, guaranteeing coil stress balance and normal refrigerator operation. In a preferred connection structure of the secondary thermal connector 6, it connects the lower connecting plate 17 of the secondary cold head and the secondary heat transfer conversion plate, and is connected by screws 18. Figure 3 The design clearly demonstrates its folded structure that bends to one side, which is beneficial for balancing the low-temperature stress of the superconducting coil and the low-temperature axial tensile force of the cold head. Due to the use of solid copper plates, it provides a sufficiently large heat transfer cross-sectional area while reducing the installation space. Of course, as it is a rigid structure, a secondary heat transfer conversion plate is specially designed to provide some installation and operation space.

[0062] The secondary heat transfer conversion plate 7 provides installation space for the secondary thermal connector 6 of the refrigerator at the radial position of the superconducting coil, while saving space on both sides and ensuring the installation accuracy of the secondary thermal connector 6. Both the secondary heat transfer conversion plate 7 and the heat transfer plate 4 are made of 8mm copper plate, machined separately, and then welded together as a whole after completion.

[0063] The excitation and energizing unit 8 is the energizing structure of the low-temperature section. One end is connected to the upper HTS energizing lead, and the other end is coupled to the on / off switch inside the junction box via a superconducting wire.

[0064] The on / off switching unit provides on / off control for the closed coil of the superconducting coil. It is coupled to the positive and negative poles of the superconducting coil and the excitation and power supply unit 8 through a junction box, and is tightly connected to the heat transfer plate 4 by high-temperature soldering.

[0065] The vacuum suction unit 10 provides degassing for the interior of the vacuum Dewar (not shown in the figure), ensuring internal vacuum maintenance. It also features a compact design located at the top. Please refer to... Figure 4 As shown, in a preferred embodiment of the vacuum suction unit 10, it includes a mounting base 19, a base plate 20, and a mounting front panel 21. These components are all made of bent aluminum alloy to ensure a stable heat transfer structure while minimizing their vertical height. Figure 1 As shown, its thickness has also been optimized to fit into narrow installation spaces.

[0066] The heat transfer metal plate is a copper plate used for heat transfer between the frame and the coil surface, and it is connected to the end-face heat-conducting plate 1. The heat transfer metal plate is made of 2mm thick copper plate, bent or stamped. During installation, it undergoes vacuum heat treatment to ensure it adheres to the frame and the outer surface of the coil. Simultaneously, low-temperature silicone grease or low-temperature epoxy is applied during installation to fill any minor contact gaps. Its structure can take various forms. In a preferred embodiment of the heat transfer metal plate, please refer to... Figure 5 As shown, Figure 5 The diagram shows a partially enlarged view of the bonding of the heat transfer copper plate 11 to the surface of the skeleton coil. It illustrates a component structure that allows the heat transfer copper plate 11 to adhere closely to the skeleton surface. A surface pressure plate 22 is provided on the heat transfer copper plate 11, its function being to press the heat transfer copper plate 11 firmly. Depending on the structural design, multiple sets of different surface pressure plates 22 can be used, ensuring that the heat transfer copper plate 11 adheres to the skeleton while the downward preload allows it to naturally conform to the coil surface without damaging the coil structure or insulation, thus guaranteeing the coil's axial heat transfer performance. Simultaneously, the tight connection between the heat transfer copper plate 11 and the end-face heat-conducting plate 1 forms a complete closed heat transfer loop from top to bottom along the secondary cold head of the refrigerator, the secondary thermal connector 6 of the refrigerator, the end-face heat-conducting plate 1, the skeleton, and the coil. This significantly improves heat transfer efficiency and minimizes the temperature difference that could potentially cause quenching.

[0067] This preferred embodiment has the following beneficial effects:

[0068] 1. A very compact superconducting coil heat transfer structure is provided. At the same time, the optimized design of each part significantly reduces the cost and further reduces the weight and space of the entire magnet. This greatly reduces the requirements for its installation conditions and site. In addition, the liquid helium-free design structure can also meet the needs of many medical institutions that do not have a helium recovery system.

[0069] 2. The innovative use of thin copper plates instead of traditional thick copper plates in the heat transfer structure, and the close connection between the secondary cold head, frame and coil in the heat transfer circuit, results in high heat transfer efficiency. The temperature difference between the secondary cold head of the refrigerator and the highest temperature point (farthest end) of the superconducting coil can be controlled within 0.1K, which greatly reduces the risk of excitation failure and improves the ease of use and stability of the equipment.

[0070] 3. The flexible connection structure was modified, replacing the use of copper braided strip with bent copper plates. Calculations were performed to ensure that the structure met the mechanical properties of the superconducting coil and the low-temperature shrinkage performance of the cold head. This maximized the heat transfer cross-sectional area of ​​the secondary cold head's thermal connection, allowing for a more relaxed requirement for copper material. This reduced costs while fully meeting design requirements.

[0071] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A compact superconducting coil heat transfer structure, applied to liquid helium-free superconducting magnets, characterized in that: The system includes a tubular superconducting coil winding frame, on the outer surface of which a flat superconducting coil assembly is wound through wire grooves; a heat transfer plate is provided on the outer side of the superconducting coil winding frame, and an end face heat-conducting plate is provided at each end of the superconducting coil winding frame. The two ends of the heat transfer plate are respectively connected to the end face heat-conducting plate at the corresponding ends. A heat transfer metal plate is also connected to the end face heat-conducting plates at both ends. The heat transfer metal plate is in contact with the superconducting coil assembly to form a closed heat transfer loop. The heat transfer plate is provided with a secondary heat transfer conversion plate on its outer side. The secondary heat transfer conversion plate is provided with a secondary heat connection component for the refrigerator. The secondary heat connection component for the refrigerator connects the refrigerator and the superconducting coil assembly. The edge of the end face heat-conducting plate has a bent connecting part, which overlaps the outside of the heat transfer plate. The heat transfer metal plate is formed by bending or stamping to create multiple embedded portions that extend into the grooves and fit against the superconducting coil assembly.

2. The compact superconducting coil heat transfer structure according to claim 1, characterized in that: The contact surface between the connecting part and the heat transfer plate is coated with a first silicone grease coating to reduce thermal resistance.

3. The compact superconducting coil heat transfer structure according to claim 1, characterized in that: The embedded part is provided with a second silicone grease coating or epoxy coating.

4. A compact superconducting coil heat transfer structure according to any one of claims 1-3, characterized in that: The refrigeration unit has two secondary thermal connectors, which are symmetrically fixed to both sides of the secondary heat transfer conversion plate by fasteners. The upper ends of the two secondary thermal connectors are simultaneously connected to the lower connecting plate of the secondary cold head of the refrigeration unit by fasteners.

5. The compact superconducting coil heat transfer structure according to claim 4, characterized in that: The secondary heat transfer conversion plate is also equipped with an excitation and power supply unit. One end of the excitation and power supply unit is connected to the HTS power supply lead, and the other end is coupled to the superconducting wire.

6. The compact superconducting coil heat transfer structure according to claim 5, characterized in that: The heat transfer plate is also provided with an on / off switch unit adjacent to the secondary heat transfer conversion plate. The on / off switch unit is coupled to the positive and negative poles of the superconducting coil and the excitation and power-on unit through a junction box.

7. The compact superconducting coil heat transfer structure according to claim 1, characterized in that: The heat transfer plate is also provided with a quench protection unit connected to the end face heat conduction plate; The quench protection unit includes a metal mounting plate, an insulating sleeve rod for conductive plates, conductive metal plates, a low-temperature diode, and an insulating base plate. The insulating base plate is connected to the end face heat-conducting plate through the metal mounting plate. Multiple parallel conductive metal plates are connected to the insulating base plate through insulating fixing components. A low-temperature diode is provided between adjacent conductive metal plates.

8. A liquid helium-free superconducting magnet, characterized in that: Including a compact superconducting coil heat transfer structure as described in any one of claims 1-7.

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