Superconducting magnet structure and magnetic resonance equipment

Abstract

This invention relates to a superconducting magnet structure and a magnetic resonance imaging (MRI) device. The superconducting magnet structure includes: a cryogenic holder comprising an outer container, a magnet assembly, and a radiation shielding layer, wherein the magnet assembly is disposed inside the outer container, and the radiation shielding layer is located between the outer container and the magnet assembly; and a cooling assembly comprising a cryostat, a first thermal switch, and a second thermal switch, wherein the cryostat is disposed within the outer container and has a first cold head and a second cold head. The first thermal switch can switch between the first cold head and the radiation shielding layer, and the second cold head is connected to the magnet assembly via the second thermal switch. By switching the cryostat between the first thermal switch and the second thermal switch and the radiation shielding layer and magnet assembly inside the superconducting magnet structure, the evaporation of liquid helium in the magnet assembly is prevented, thereby avoiding quench loss and ensuring the performance of the superconducting magnet structure.

Description

Technical Field

[0001] This invention relates to the field of medical imaging equipment technology, and in particular to a superconducting magnet structure and magnetic resonance imaging device. Background Technology

[0002] In MR (Magnetic Resonance) equipment, the cold head is one of the key components for maintaining the cryogenic temperature of the superconducting magnet and preventing liquid helium from evaporating. The cold head consists of a primary and a secondary stage. The primary stage maintains the cryogenic temperature of the cooling screen, while the secondary stage liquefies the helium gas into liquid helium. The cold head is typically connected to the cooling screen and the liquid helium tank using a highly thermally conductive connection method, allowing the cooling energy from the cold head to be efficiently transferred to the interior of the superconducting magnet.

[0003] However, when the cold head is shut down or replaced, it ceases to provide cooling and becomes a good conductor. External heat is first transferred to the cold head, making it easy for heat to enter the superconducting magnet through this highly thermally conductive connection. This causes the cooling screen temperature to rise, liquid helium to evaporate, and liquid helium to be lost. This is especially problematic for low-liquid-helium or helium-free magnets. After the cold head shuts down, without a large amount of liquid helium as a heat sink, heat is quickly transferred to the superconducting coils, easily causing quench failure and affecting the performance of the superconducting magnet. Summary of the Invention

[0004] Therefore, it is necessary to provide a superconducting magnet structure and magnetic resonance device that can control the on / off state of the cold energy transfer path to address the quenching problem caused by the cold head of the refrigerator transferring heat to the interior when the refrigerator is shut down or replaced.

[0005] A superconducting magnet structure, comprising:

[0006] A cryogenic holder includes an outer container, a magnet assembly, and a radiation shielding layer, wherein the magnet assembly is disposed inside the outer container, and the radiation shielding layer is located between the outer container and the magnet assembly; and

[0007] A refrigeration assembly includes a refrigeration unit, a first thermal switch, and / or a second thermal switch. The refrigeration unit is disposed in the outer container and has a first cold head and a second cold head. The first thermal switch can connect the first cold head to the radiation shielding layer. The second cold head is connected to the magnet assembly through the second thermal switch.

[0008] In one embodiment, the first thermal switch includes a first housing, a first cold end, and a first hot end. The first housing is hollow, and the first cold end and the first hot end are respectively disposed at both ends of the first housing. The first cold end is connected to the first cold head, and the first hot end is connected to the radiation shielding layer.

[0009] The interior of the first housing is filled with a first cooling medium capable of gas-liquid conversion.

[0010] In one embodiment, the second thermal switch includes a second housing, a second cold end, and a second hot end. The second housing is hollow, and the second cold end and the second hot end are respectively disposed at both ends of the second housing. The second cold end is connected to the second cold head, and the second hot end is connected to the magnet assembly.

[0011] The interior of the second housing is filled with a second cooling medium capable of gas-liquid conversion.

[0012] In one embodiment, the boiling point range of the first cooling medium is different from that of the second cooling medium.

[0013] In one embodiment, the first thermal switch and the second thermal switch are retractable components. When the first thermal switch is cooled, it can extend to connect the first cold head to the radiation shielding layer, and when the second thermal switch is cooled, it can extend to connect the second cold head to the magnet assembly.

[0014] In one embodiment, the magnet assembly includes an inner container and a superconducting coil disposed within the inner container, with the second thermal switch connected to the inner container; or, the second thermal switch is connected to the superconducting coil.

[0015] In one embodiment, the number of the first thermal switches is one or more, and when the number of the first thermal switches is multiple, the multiple first thermal switches are spaced apart.

[0016] The number of the second thermal switches is one or more. When the number of the second thermal switches is multiple, the multiple second thermal switches are arranged at intervals.

[0017] In one embodiment, the cooling assembly further includes a first connector and a second connector, wherein the first connector is connected to both ends of the first thermal switch to connect the first cold head and the radiation shielding layer respectively;

[0018] The second connector is connected to both ends of the second thermal switch to connect the second cold head and the magnet assembly respectively.

[0019] A magnetic resonance imaging (MRI) device includes a gradient coil, a radio frequency (RF) coil, and a superconducting magnet structure. The superconducting magnet structure has a scanning aperture, the RF coil is disposed in the scanning aperture, and the gradient coil is located between the RF coil and the superconducting magnet structure. The superconducting magnet structure includes:

[0020] A cryogenic holder includes an outer container, a magnet assembly, and a radiation shielding layer, wherein the magnet assembly is disposed inside the outer container, and the radiation shielding layer is located between the outer container and the magnet assembly; and

[0021] Refrigeration components, including:

[0022] A refrigeration unit is installed in the outer container;

[0023] A connector for connecting the refrigerator and the magnet assembly, or for connecting the refrigerator and the radiation shielding layer;

[0024] A thermal switch is connected in series with the connector. The thermal switch contains a cooling medium, and changes in the state of the cooling medium cause the thermal switch to be in an on or off mode.

[0025] In one embodiment, the thermal switch includes a first thermal switch and / or a second thermal switch;

[0026] The first thermal switch includes a first housing, a first cold end, and a first hot end. The first housing is hollow. The first cold end and the first hot end are respectively disposed at both ends of the first housing. The first cold end is connected to the first cold head, and the first hot end is connected to the radiation shielding layer. The interior of the first housing is filled with a first cooling medium capable of gas-liquid conversion.

[0027] The second thermal switch includes a second housing, a second cold end, and a second hot end. The second housing is hollow. The second cold end and the second hot end are respectively disposed at both ends of the second housing. The second cold end is connected to the second cold head, and the second hot end is connected to the radiation shielding layer. The interior of the second housing is filled with a second cooling medium capable of gas-liquid conversion.

[0028] By adopting the above technical solution, the present invention has at least the following technical effects:

[0029] The superconducting magnet structure and magnetic resonance device of the present invention include a first cold head of a cryostat connected to a radiation shielding layer via a first thermal switch, and a second cold head connected to a magnet assembly via a second thermal switch. When the cryostat is operating, the first thermal switch enables heat transfer / coupling between the first cold head and the radiation shielding layer, and the second thermal switch enables heat coupling between the second cold head and the magnet assembly. The cooling capacity of the cryostat can be transferred to the radiation shielding layer via the first cold head and the first thermal switch, and to the magnet assembly via the second cold head and the second thermal switch. When the cryostat is not operating or when the cryostat is replaced, the first and second thermal switches are disconnected, preventing external heat from being transferred to the radiation shielding layer and the magnet assembly via these switches. By connecting the refrigerator to the radiation shielding layer and magnet components inside the superconducting magnet structure through the on / off switching of the first and second thermal switches, the refrigerator and the superconducting magnet structure are connected when the refrigerator is working. When the refrigerator is not working or is being replaced, the first and second thermal switches are disconnected to form an open circuit, preventing heat transfer or inhibiting heat transfer. This effectively solves the problem of quenching caused by the cold head of the refrigerator transferring heat to the interior when the refrigerator is stopped or replaced, thus preventing the evaporation of liquid helium in the magnet components and avoiding quenching, ensuring the performance of the superconducting magnet structure. Attached Figure Description

[0030] Figure 1 This is a partial schematic diagram of a superconducting magnet structure according to an embodiment of the present invention;

[0031] Figure 2 for Figure 1 A three-dimensional view of the cooling component in the superconducting magnet structure shown;

[0032] Figure 3 for Figure 1 A schematic diagram of the first thermal switch being turned on in the superconducting magnet structure shown;

[0033] Figure 4 for Figure 1 A schematic diagram of the superconducting magnet structure when the first thermal switch is disconnected;

[0034] Figure 5 for Figure 1 A schematic diagram of the second thermal switch being turned on in the superconducting magnet structure shown;

[0035] Figure 6 for Figure 1 A schematic diagram of the second thermal switch being disconnected in the superconducting magnet structure shown.

[0036] Wherein: 100, superconducting magnet structure; 110, cryogenic holder; 111, outer container; 112, magnet assembly; 1121, inner container; 1122, superconducting coil; 113, radiation shielding layer; 120, cooling assembly; 121, refrigerator; 1211, first cold head; 1212, second cold head; 122, first thermal switch; 1221, first housing; 1222, first cold end; 1223, first hot end; 1224, first cooling medium; 123, second thermal switch; 1231, second housing; 1232, second cold end; 1233, second hot end; 1234, second cooling medium; 124, first connector; 125, second connector. Detailed Implementation

[0037] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0038] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0039] 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 invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0040] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," 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 or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0042] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0043] See Figure 1 and Figure 2 This invention provides a superconducting magnet structure 100. This superconducting magnet structure 100 is used in a magnetic resonance imaging (MRI) device to image a specific area, obtaining image information of that area to facilitate diagnosis by medical personnel. It is understood that the imaging area here typically refers to the location of the patient's lesion; however, in other embodiments of this invention, the imaging area can be other locations requiring imaging.

[0044] In current magnetic resonance imaging (MRI) devices, the cold head generates cooling energy and transfers it to the interior to cool the superconducting magnet, ensuring its proper functioning and imaging quality. However, when the cold head is shut down or needs replacement, it stops cooling. In this case, the cold head transfers heat from the outside to the interior, causing the internal temperature of the superconducting magnet to rise, which can lead to liquid helium evaporation and a high risk of quench failure.

[0045] To address this, the present invention provides a novel superconducting magnet structure 100 that prevents heat transfer to the interior of the superconducting magnet structure 100, thereby preventing liquid helium evaporation, avoiding quench loss, ensuring the performance of the superconducting magnet structure 100, and consequently ensuring the performance of the magnetic resonance imaging (MRI) device. The specific structure of the superconducting magnet structure 100 is described in detail below.

[0046] See Figure 1 and Figure 2 In one embodiment, the superconducting magnet structure 100 includes a cryogenic holder 110 and a cooling assembly 120. The cryogenic holder 110 includes an outer container 111, a magnet assembly 112, and a radiation shielding layer 113, which can be coaxially or non-coaxially arranged. The magnet assembly 112 is disposed inside the outer container 111, and the radiation shielding layer 113 is located between the outer container 111 and the magnet assembly 112. The refrigeration assembly 120 includes a refrigerator 121, a first thermal switch 122, and a second thermal switch 123. The refrigerator 121 is disposed in the outer container 111. The refrigerator 121 has a first cold head 1211 and a second cold head 1212. The first thermal switch 122 can switch the connection between the first cold head 1211 and the radiation shielding layer 113, that is, the efficiency of heat transfer between the first cold head 1211 and the radiation shielding layer 113 is controlled by the first thermal switch 122. The second cold head 1212 is connected to the magnet assembly 112 through the second thermal switch 123, and the efficiency of heat transfer between the second cold head 1212 and the magnet assembly 112 is controlled by the first thermal switch 122.

[0047] The cryogenic holder 110 is the main structure of the superconducting magnet structure 100, used to house the various components of the superconducting magnet structure 100 and maintain it at a low temperature to ensure the performance of the superconducting magnet structure 100. Specifically, the cryogenic holder 110 includes an outer container 111, a magnet assembly 112 disposed within the outer container 111, and a radiation shielding layer 113 disposed between the outer container 111 and the magnet assembly 112. The outer container 111 has a through hole extending in the axial direction, which is the magnet hole of the magnetic resonance device. The outer container 111 is an annular closed structure, and the magnet assembly 112 is coaxially arranged with the outer container 111, and the magnet assembly 112 is disposed inside the outer container 111.

[0048] There is a space between the magnet assembly 112 and the outer container 111, which is a vacuum environment. The vacuum environment reduces the radiation of cold energy from the magnet assembly 112 and minimizes the conduction of external heat to the inner magnet assembly 112, ensuring that the magnet assembly 112 is in a low-temperature environment. Furthermore, a radiation shielding layer 113 is installed in this space, surrounding the magnet assembly 112. The radiation shielding layer 113 further isolates external radiated heat, preventing external heat from radiating to the magnet assembly 112.

[0049] Understandably, the magnet assembly 112 includes an inner container 1121 and a superconducting coil 1122 disposed within the inner container 1121. The inner container 1121 holds a cooling medium, which can be liquid helium, hyperpolarizing materials, etc. The cooling medium can be directly or indirectly thermally coupled to the superconducting coil 1122. The superconducting coil 1122 can be immersed in the cooling medium; alternatively, the cooling medium can be contained within a pipe, and the pipe can be thermally coupled to the superconducting coil 1122. Cooling the superconducting coil 1122 with the cooling medium reduces its temperature, ensuring its performance and preventing quench loss. The specific structure of the magnet assembly 112 will be mentioned later; here, it is simply referred to as the magnet assembly 112.

[0050] The cooling component 120 is disposed in the cryogenic holder 110, specifically in the outer container 111 of the cryogenic holder 110. The cooling component 120 can cool the magnet component 112 and the radiation shielding layer 113 of the cryogenic holder 110, reduce the temperature of the radiation shielding layer 113, prevent the radiation shielding layer 113 from transferring heat to the magnet component 112, thereby reducing the temperature of the magnet component 112, ensuring the performance of the magnet component 112, and preventing overrunning.

[0051] Specifically, the cooling assembly 120 includes a refrigerator 121, a first thermal switch 122, and / or a second thermal switch 123. The refrigerator 121 includes a first cold head 1211 and a second cold head 1212. When the refrigerator 121 is working, the cooling energy generated by the refrigerator 121 can be transferred to the first cold head 1211 and the second cold head 1212, and then the first cold head 1211 and the second cold head 1212 respectively transfer the cooling energy to the radiation shielding layer 113 and the magnet assembly 112.

[0052] Understandably, the refrigeration component includes a thermal switch and a connector, with the thermal switch having both on and off modes. The connector connects the refrigeration unit and the magnet assembly, and / or connects the refrigeration unit and the radiation shielding layer. When the thermal switch is on, thermal coupling occurs between the refrigeration unit and the magnet assembly, or between the refrigeration unit and the radiation shielding layer; when the thermal switch is off, thermal isolation occurs between the refrigeration unit and the magnet assembly, or between the refrigeration unit and the radiation shielding layer. Understandably, by controlling the on / off state of the cooling energy transfer path through the thermal switch, both cooling and radiation shielding effects are guaranteed.

[0053] Optionally, the thermal switch includes a first thermal switch 122 and / or a second thermal switch 123. That is, the number of thermal switches can be one, which can be either the first thermal switch 122 or the second thermal switch 123. In other embodiments of the present invention, the number of thermal switches is two, that is, the thermal switches include the first thermal switch 122 and the second thermal switch 123. This invention is only described using the example of two thermal switches; the structure and principle of one thermal switch are substantially the same as those of two thermal switches, and will not be described in detail here.

[0054] The first cold head 1211 is connected to the radiation shielding layer 113 via a first thermal switch 122. When the refrigerator 121 is working, the first thermal switch 122 is in the open mode, enabling the first cold head 1211 to connect with the radiation shielding layer 113. At this time, the cooling energy generated by the refrigerator 121 can be conducted to the radiation shielding layer 113 through the first thermal switch 122 to cool the radiation shielding layer 113, reducing its temperature and thus reducing radiative heat transfer from the outer container 111 to the magnet assembly 112. When the refrigerator 121 is stopped or replaced, the first thermal switch 122 can reduce the thermal coupling efficiency between the first cold head 1211 and the radiation shielding layer 113, or even block the thermal coupling between them. In this embodiment, the first thermal switch 122 is in a fully closed mode, and there is an open circuit between the first cold head 1211 and the radiation shielding layer 113. The heat generated by the refrigerator 121 cannot be conducted to the radiation shielding layer 113 through the first thermal switch 122. Although the first cold head 1211 is a good conductor of heat, because the first thermal switch 122 disconnects the connection between the first cold head 1211 and the radiation shielding layer 113, external heat will not be transferred to the radiation shielding layer 113 through the first thermal switch 122 via the first cold head 1211, thus ensuring the radiation shielding effect on the external container 111.

[0055] The second cold head 1212 is connected to the magnet assembly 112 via a second thermal switch 123. When the refrigerator 121 is working, the second thermal switch 123 is in the open mode, allowing the second cold head 1212 to connect to the magnet assembly 112. At this time, the cooling energy generated by the refrigerator 121 can be conducted to the magnet assembly 112 through the second thermal switch 123 to cool the magnet assembly 112 and lower its temperature. When the refrigerator 121 is stopped or replaced, the second thermal switch 123 is in the initial closed mode, reducing the thermal coupling efficiency between the second cold head 1212 and the magnet assembly 112. As the temperature difference between the second cold head 1212 and the magnet assembly 112 increases, the second thermal switch 123 is in the fully closed mode, creating an open circuit between the second cold head 1212 and the magnet assembly 112, preventing the heat generated by the refrigerator 121 from being conducted to the magnet assembly 112 through the second thermal switch 123. Although the second cold head 1212 is a good conductor of heat, since the second thermal switch 123 disconnects the connection between the second cold head 1212 and the magnet assembly 112, external heat will not be transferred to the magnet assembly 112 through the second cold head 1212 and the second thermal switch 123, thus ensuring the cooling effect on the magnet assembly 112.

[0056] In other words, the refrigerator 121 is connected to the radiation shielding layer 113 and the magnet assembly 112 by switching the first thermal switch 122 and the second thermal switch 123 on and off. When the refrigerator 121 is working, the first thermal switch 122 and the second thermal switch 123 are in the conducting state, and the cooling capacity of the refrigerator 121 can be transferred to the radiation shielding layer 113 and the magnet assembly 112 through the first thermal switch 122 and the second thermal switch 123 respectively, reducing the temperature of the magnet assembly 112 and preventing overrunning of the coil. When the refrigerator 121 is not working or needs to be replaced, the first thermal switch 122 and the second thermal switch 123 disconnect the refrigerator 121 from the radiation shielding layer 113 and the magnet assembly 112, preventing external heat from being transferred to the internal magnet assembly 112 and radiation shielding layer 113 through the first cold head 1211 and the second cold head 1212 of the refrigerator 121, thereby preventing the loss of cooling medium in the magnet assembly 112 and reducing maintenance costs.

[0057] The superconducting magnet structure 100 of the above embodiment connects the refrigerator 121 with the radiation shielding layer 113 and the magnet assembly 112 inside the superconducting magnet structure 100 through the on / off connection of the first thermal switch 122 and the second thermal switch 123. This effectively solves the problem of quenching caused by the cold head of the refrigerator transferring heat to the interior when the refrigerator is stopped or replaced. This avoids the evaporation of liquid helium in the magnet assembly 112, thereby preventing quenching and ensuring the performance of the superconducting magnet structure 100.

[0058] Optionally, the outer container 111 includes a first outer cylinder, a first inner cylinder, and a first end plate. The first inner cylinder and the first outer cylinder are hollow cylindrical structures, respectively arranged radially from the center inwards. First end plates are respectively provided at both ends of the first inner cylinder. The first end plates are annular structures, and are respectively connected to the first inner cylinder and the first outer cylinder to seal them. Optionally, the outer container 111 is made of metal or composite material; further, it can be made of carbon steel or stainless steel.

[0059] Optionally, the inner container 1121 includes a second outer cylinder, a second inner cylinder, and a second end plate. The second inner cylinder and the second outer cylinder are hollow cylindrical structures, respectively arranged radially from the center inwards. Second end plates, which are annular structures, are respectively provided at both ends of the second inner cylinder, connecting to the second inner cylinder and the second outer cylinder to seal them respectively. Optionally, the inner container 1121 is made of metal or composite material; further, it can be made of carbon steel or stainless steel.

[0060] Optionally, the radiation shielding layer 113 includes a third outer cylinder, a third inner cylinder, and a third end plate. The third inner cylinder and the third outer cylinder are hollow cylindrical structures, respectively arranged radially from the center inwards. Third end plates are respectively provided at both ends of the third inner cylinder. The third end plates are annular structures, connected to the third inner cylinder and the third outer cylinder respectively, to seal them. Specifically, the third inner cylinder is located between the first inner cylinder and the second inner cylinder, the third outer cylinder is located between the first outer cylinder and the second outer cylinder, and the third end plate is located between the first end plate and the second end plate.

[0061] See Figures 1 to 4 In one embodiment of the present invention, the first thermal switch 122 includes a first housing 1221, a first cold end 1222, and a first hot end 1223. The first housing 1221 is hollow. The first cold end 1222 and the first hot end 1223 are respectively disposed at both ends of the first housing 1221. The first cold end 1222 is connected to the first cold head 1211, and the first hot end 1223 is connected to the radiation shielding layer 113. The interior of the first housing 1221 is filled with a first cooling medium 1224 capable of gas-liquid conversion.

[0062] The first housing 1221 is a hollow, closed structure, and its interior is filled with a first cooling medium 1224. The first cooling medium 1224 is capable of gas-liquid conversion. In the first housing 1221, the gaseous first cooling medium 1224 accumulates at the top, while the liquid first cooling medium 1224 accumulates at the bottom under gravity. A first cold end 1222 is located at the top of the first housing 1221, with one end extending into the interior and the other end connected to the first cold head 1211. Thus, the first cold end 1222 can contact the first cooling medium 1224 within the first housing 1221, enabling the first cold head 1211 to transfer cooling energy to the first cooling medium 1224. The first hot end 1223 is disposed at the bottom of the first housing 1221, and one end of the first hot end 1223 extends into the interior of the first housing 1221, while the other end of the first hot end 1223 is connected to the radiation shielding layer 113. In this way, the first hot end 1223 can come into contact with the first cooling medium 1224 in the first housing 1221, and the cooling medium 1224 can transfer cold energy to the radiation shielding layer 113 through the first hot end 1223.

[0063] See Figure 1 and Figure 3 When the refrigerator 121 is operating, the first thermal switch 122 connects the first cold head 1211 to the radiation shielding layer 113. Specifically, the cooling energy of the refrigerator 121 is transferred to the first cold head 1211. Since the first cold end 1222 is connected to the first cold head 1211, the cooling energy of the first cold head 1211 can be transferred to the first cold end 1222. The first cold end 1222 can transfer the cooling energy into the interior of the first housing 1221. The end of the first cold end 1222 can contact the gaseous first cooling medium 1224 in the first housing 1221 to transfer cooling energy to the first cooling medium 1224.

[0064] Understandably, the cooling energy received by the first cold end 1222 is lower than the boiling point of the first cooling medium 1224. When the gaseous first cooling medium 1224 absorbs the cooling energy transferred from the first cold end 1222, it liquefies on the end surface of the first cold end 1222. The liquefied first cooling medium 1224 flows downwards to the bottom of the first housing 1221 under gravity, forming a liquid accumulation. The liquid first cooling medium 1224 can contact the end of the first hot end 1223, causing the temperature of the first hot end 1223 to drop to the boiling point of the first cooling medium 1224, thus achieving the purpose of lowering the temperature of the first hot end 1223.

[0065] While the liquid first cooling medium 1224 transfers cooling energy to the first hot end 1223, the liquid first cooling medium 1224 absorbs heat from the first hot end 1223. After absorbing heat, the liquid first cooling medium 1224 evaporates into a gaseous state, forming a gaseous first cooling medium 1224. The gaseous first cooling medium 1224 rises in the first housing 1221 and comes into contact with the first cold end 1222. This process repeats, transferring the cooling energy from the first cold end 1222 to the first hot end 1223 through the gas-liquid conversion of the first cooling medium 1224. At this time, the first thermal switch 122 is in the open mode. Moreover, after absorbing cooling energy, the first hot end 1223 can transfer the cooling energy to the radiation shielding layer 113, exchange heat with the radiation shielding layer 113, and reduce the temperature of the radiation shielding layer 113. At the same time, the heat from the radiation shielding layer 113 is transferred to the first hot end 1223.

[0066] See Figure 1 and Figure 4 When the refrigerator 121 is not working, it no longer generates cooling, and the first cold head 1211 cannot receive cooling. Simultaneously, external heat is transferred to the first cold head 1211, resulting in a higher temperature. Because the first cold head 1211 is in contact with the first cold end 1222, it transfers heat to the first cold end 1222, causing its temperature to rise above the boiling point of the first cooling medium 1224. At this time, the gaseous cooling medium in contact with the first cold end 1222 will not liquefy. Furthermore, after the heat from the radiation shielding layer 113 is transferred to the first hot end 1223, the liquid first cooling medium 1224 below the first housing 1221 absorbs the heat from the first hot end 1223 and evaporates into a gaseous state, forming a gaseous first cooling medium 1224. Thus, the interior of the first housing 1221 is filled with the gaseous first cooling medium 1224.

[0067] In addition, since the temperature of the first hot end 1223 is lower than that of the first cold end 1222, the gaseous first cooling medium 1224 in the first housing 1221 is in a state of being hot on top and cold on the bottom, forming a natural temperature stratification. This results in low transfer efficiency of the gaseous first cooling medium 1224 in the first housing 1221. At this time, the first thermal switch 122 is in the off mode, blocking the heat from the first cold end 1222 from entering the first hot end 1223, thus realizing the transfer of cold energy.

[0068] Optionally, the first housing 1221 is made of a material with poor thermal conductivity. Further, the first housing 1221 is made of stainless steel. Of course, in other embodiments of the invention, the first housing 1221 may also be made of other materials with poor thermal conductivity, such as ceramics.

[0069] Optionally, the first cold end 1222 and the first hot end 1223 are made of a material with high thermal conductivity. Further, the first cold end 1222 and the first hot end 1223 are made of copper to ensure good thermal conductivity. Of course, in other embodiments of the present invention, the first cold end 1222 and the first hot end 1223 may also be made of other materials with good thermal conductivity. Optionally, the ends of the first hot end 1223 and the first cold end 1222 are provided with connecting threads to facilitate connection with other components.

[0070] See Figure 1 , Figure 2 , Figure 5 and Figure 6 In one embodiment, the second thermal switch 123 includes a second housing 1231, a second cold end 1232, and a second hot end 1233. The second housing 1231 is hollow. The second cold end 1232 and the second hot end 1233 are respectively disposed at both ends of the second housing 1231. The second cold end 1232 is connected to the second cold head 1212, and the second hot end 1233 is connected to the magnet assembly 112. The interior of the second housing 1231 is filled with a second cooling medium 1234 capable of gas-liquid conversion.

[0071] The second housing 1231 is a hollow, closed structure, and its interior is filled with a second cooling medium 1234. The second cooling medium 1234 is capable of gas-liquid conversion. In the second housing 1231, the gaseous second cooling medium 1234 accumulates at the top, while the liquid second cooling medium 1234 accumulates at the bottom under gravity. A second cold end 1232 is located at the top of the second housing 1231, with one end extending into the interior and the other end connected to the second cold head 1212. Thus, the second cold end 1232 can contact the second cooling medium 1234 within the second housing 1231, enabling the second cold head 1212 to transfer cooling energy to the second cooling medium 1234. The second hot end 1233 is disposed at the bottom of the second housing 1231, with one end extending into the interior of the second housing 1231 and the other end connected to the magnet assembly 112. Thus, the second hot end 1233 can contact the second cooling medium 1234 in the second housing 1231, enabling the second cooling medium 1234 to transfer cooling energy to the magnet assembly 112.

[0072] See Figure 1 and Figure 5When the refrigerator 121 is operating, the second thermal switch 123 connects the second cold head 1212 to the magnet assembly 112. Specifically, the cooling energy of the refrigerator 121 is transferred to the second cold head 1212. Since the second cold end 1232 is connected to the second cold head 1212, the cooling energy of the second cold head 1212 can be transferred to the second cold end 1232. The second cold end 1232 can transfer the cooling energy into the interior of the second housing 1231. The end of the second cold end 1232 can contact the gaseous second cooling medium 1234 in the second housing 1231 to transfer cooling energy to the second cooling medium 1234.

[0073] Understandably, the cooling energy received by the second cold end 1232 is lower than the boiling point of the second cooling medium 1234. When the gaseous second cooling medium 1234 absorbs the cooling energy transferred from the second cold end 1232, it liquefies on the end surface of the second cold end 1232. The liquefied second cooling medium 1234 flows downwards to the bottom of the second housing 1231 under gravity, forming a liquid accumulation. The liquid second cooling medium 1234 can contact the end of the second hot end 1233, causing the temperature of the second hot end 1233 to drop to the boiling point of the second cooling medium 1234, thus achieving the purpose of lowering the temperature of the second hot end 1233.

[0074] While the liquid second cooling medium 1234 transfers cooling energy to the second hot end 1233, it also absorbs heat from the hot end 1233. After absorbing heat, the liquid cooling medium evaporates into a gaseous state, forming a gaseous second cooling medium 1234. This gaseous cooling medium rises within the second housing 1231 and comes into contact with the second cold end 1232. This process repeats, transferring the cooling energy from the cold end 1232 to the hot end 1233 through the gas-liquid exchange of the second cooling medium 1234. At this time, the second thermal switch 123 is in the open mode. Furthermore, after absorbing cooling energy, the hot end 1233 can transfer it to the magnet assembly 112 for heat exchange, lowering the temperature of the magnet assembly 112. Simultaneously, the heat from the magnet assembly 112 is transferred to the hot end 1233.

[0075] See Figure 1 and Figure 6When the refrigerator 121 is not working, it no longer generates cooling, and the second cold head 1212 cannot receive cooling. Simultaneously, external heat is transferred to the second cold head 1212, resulting in a higher temperature. Because the second cold head 1212 is in contact with the second cold end 1232, it transfers heat, causing the temperature of the second cold end 1232 to rise above the boiling point of the second cooling medium 1234. At this time, the gaseous cooling medium in contact with the second cold end 1232 will not liquefy. Furthermore, after the heat from the magnet assembly 112 is transferred to the second hot end 1233, the liquid second cooling medium 1234 below the second housing 1231 absorbs the heat from the second hot end 1233 and evaporates into a gaseous state, forming a gaseous second cooling medium 1234. Thus, the interior of the second housing 1231 is filled with the gaseous second cooling medium 1234.

[0076] In addition, since the temperature of the second hot end 1233 is lower than that of the second cold end 1232, the gaseous second cooling medium 1234 in the second shell 1231 is in a state of being hot on top and cold on the bottom, forming a natural temperature stratification. This results in low transfer efficiency of the gaseous second cooling medium 1234 in the second shell 1231. At this time, the second thermal switch 123 is in the closed mode, blocking the heat from the second cold end 1232 from entering the second hot end 1233, thus realizing the transfer of cold energy.

[0077] Optionally, the second housing 1231 is made of a material with poor thermal conductivity. Further, the second housing 1231 is made of stainless steel. Of course, in other embodiments of the invention, the second housing 1231 may also be made of other materials with poor thermal conductivity, such as ceramics.

[0078] Optionally, the second cold end 1232 and the second hot end 1233 are made of a material with high thermal conductivity. Further, the second cold end 1232 and the second hot end 1233 are made of copper to ensure good thermal conductivity. Of course, in other embodiments of the present invention, the second cold end 1232 and the second hot end 1233 may also be made of other materials with good thermal conductivity. Optionally, the ends of the second hot end 1233 and the second cold end 1232 are provided with connecting threads to facilitate connection with other components.

[0079] Understandably, the first cold head 1211 and the second cold head 1212 of the refrigerator 121 have different power and cooling capacity during operation. The first cold head 1211 includes a first cooler and a first copper block, which is connected to the first cold end 1222. Typically, the temperature of the first cold head 1211 is 30K–50K, and its cooling power is approximately 45W. The first cold head 1211 transfers the cooling capacity generated by the first cooler to the first cold end 1222 through the first copper block. The second cold head 1212 includes a second cooler and a second copper block, which is connected to the second cold end 1232. Typically, the temperature of the second cold head 1212 is approximately 4.2K, and its cooling power is approximately 1W. The second cold head 1212 transfers the cooling capacity generated by the second cooler to the second cold end 1232 through the second copper block.

[0080] Because the cooling capacity generated by the first cold head 1211 and the second cold head 1212 is different, the boiling points of the first cooling medium 1224 in the first thermal switch 122 (which cooperates with the first cold head 1211) and the second cooling medium 1234 (which cooperates with the second cold head 1212) are also different. Optionally, the first cooling medium 1224 is a gas with a boiling point range of 35K to 50K. Optionally, the first cooling medium 1224 can be neon or a mixture thereof. Optionally, the second cooling medium 1234 is a gas with a boiling point range of 3K to 5K. Optionally, the second cooling medium 1234 can be argon or a mixture thereof.

[0081] Optionally, the volume of the second thermal switch 123 is smaller than that of the first thermal switch 122. This can reduce the space occupied while ensuring the cooling effect.

[0082] In another embodiment of the present invention, the first thermal switch 122 and the second thermal switch 123 are retractable components. When the first thermal switch 122 is cooled, it can extend to connect the first cold head 1211 and the radiation shielding layer 113. When the second thermal switch 123 is cooled, it can extend to connect the second cold head 1212 and the magnet assembly 112.

[0083] In other words, the first thermal switch 122 and the second thermal switch 123 are retractable components. When the refrigerator 121 is working, the first thermal switch 122 extends, connecting the first cold head 1211 to the radiation shielding layer 113; the second thermal switch 123 extends, connecting the second cold head 1212 to the magnet assembly 112. When the refrigerator 121 is not working, the first thermal switch 122 and the second thermal switch 123 retract, causing the first thermal switch 122 to disconnect the first cold head 1211 from the radiation shielding layer 113, and the second thermal switch 123 to disconnect the second cold head 1212 from the magnet assembly 112.

[0084] For example, the first thermal switch 122 and the second thermal switch 123 are inflatable bellows or the like. The first thermal switch 122 is disposed on the first cold head 1211, and the second thermal switch 123 is disposed on the second cold head 1212. After the first thermal switch 122 is inflated, it expands and can connect to the radiation shielding layer 113. After the second thermal switch 123 is inflated, it can connect to the magnet assembly 112. When the first thermal switch 122 deflates, it detaches from the radiation shielding layer 113. After the second thermal switch 123 is deflated, it detaches from the magnet assembly 112.

[0085] Of course, in other embodiments of the present invention, the first thermal switch 122 and the second thermal switch 123 may also be made of other structures that can be stretched to achieve switching.

[0086] In one embodiment, the magnet assembly 112 includes an inner container 1121 and a superconducting coil 1122 disposed within the inner container 1121, with a second thermal switch 123 connected to the inner container 1121; or, the second thermal switch 123 is connected to the superconducting coil 1122. That is, the second hot end 1233 of the second thermal switch 123 can be directly connected to the inner container 1121 to reduce its temperature, cool the liquid helium within the inner container 1121, and thus lower the temperature of the superconducting coil 1122. Alternatively, the second hot end 1233 of the second thermal switch 123 can also be directly connected to the superconducting coil 1122 to directly lower its temperature. Further, the superconducting coil 1122 includes a coil body and a coil support, with the second thermal switch 123 connected to either the coil body or the coil support. Both methods achieve the goal of lowering the temperature of the superconducting coil 1122.

[0087] See Figure 2 In one embodiment, the number of first thermal switches 122 is one or more. When there are multiple first thermal switches 122, they are spaced apart. When there are multiple first thermal switches 122, each is connected to the radiation shielding layer 113, which can reduce the temperature of the radiation shielding layer 113 and ensure its cooling effect. Alternatively, the temperature of the heat radiation shielding layer 113 can be reduced using only one first thermal switch 122. Exemplarily, the number of first thermal switches 122 is two. Of course, in other embodiments of the present invention, the number of first thermal switches 122 can also be one, three, or more.

[0088] In one embodiment, the number of second thermal switches 123 is one or more, and when there are multiple second thermal switches 123, they are spaced apart. When there are multiple second thermal switches 123, each is connected to the magnet assembly 112, which can reduce the temperature of the magnet assembly 112 and ensure the cooling effect of the magnet assembly 112. Of course, the temperature of the heat radiation shielding layer 113 can also be reduced using only one second thermal switch 123. Exemplarily, the number of second thermal switches 123 is one. Of course, in other embodiments of the present invention, the number of second thermal switches 123 can also be two or more.

[0089] See Figure 1 In one embodiment, the outer container 111 has a cold head cavity for mounting a first cold head 1211 and a second cold head 1212. A first thermal switch 122 is connected to a first copper block of the first cold head 1211 in the cold head cavity, and a second thermal switch 123 is connected to a second copper block of the second cold head 1212 in the cold head cavity. Of course, in other embodiments of the invention, the outer container 111 may not have a cold head cavity; the first thermal switch 122 connects to the first cold head 1211 in the space between the outer container 111 and the inner container 1121, and the second thermal switch 123 connects to the second cold head 1212 in the space between the outer container 111 and the inner container 1121.

[0090] See Figure 2 In one embodiment, the cooling assembly 120 further includes a first connector 124 and a second connector 125. The first connector 124 is connected to both ends of the first thermal switch 122 to connect the first cold head 1211 and the radiation shielding layer 113, respectively. The second connector 125 is connected to both ends of the second thermal switch 123 to connect the second cold head 1212 and the magnet assembly 112, respectively.

[0091] Each first thermal switch 122 corresponds to two first connectors 124. One first connector 124 connects the first cold end 1222 of the first thermal switch 122 to the first cold head 1211, and the other first connector 124 connects the first hot end 1223 to the radiation shielding layer 113. The cooling energy of the first cold head 1211 is transferred to the first cold end 1222 through the first connector 124, and then the first hot end 1223 transfers the cooling energy to the radiation shielding layer 113 through the first connector 124, thereby realizing the transfer of cooling energy. Optionally, the first connector 124 is made of a high thermal conductivity material. Further, the first connector 124 is a copper strip or other thermally conductive component.

[0092] Each second thermal switch 123 corresponds to two second connectors 125. One second connector 125 connects the second cold end 1232 of the second thermal switch 123 to the second cold head 1212, and the other second connector 125 connects the second hot end 1233 to the magnet assembly 112. The cooling energy of the second cold head 1212 is transferred to the second cold end 1232 through the second connector 125, and then the second hot end 1233 transfers the cooling energy to the magnet assembly 112 through the second connector 125, thereby realizing the transfer of cooling energy. Optionally, the second connector 125 is made of a high thermal conductivity material. The second connector 125 may extend into the interior of the inner container 1121 to cool the cooling medium contained in the inner container 1121, or the second connector 125 may extend into the pipe containing the cooling medium. Further, the second connector 125 is a copper strip or other thermally conductive component.

[0093] See Figures 1 to 6 The superconducting magnet structure 100 of the present invention establishes the connection and disconnection of the cold energy transmission channel between the refrigerator 121 and the internal cold energy transmission channel of the superconducting magnet structure 100 through a first thermal switch 122 and a second thermal switch 123. When the refrigerator 121 is working, the first thermal switch 122 and the second thermal switch 123 conduct the cold energy transmission channel, which can cool the radiation shielding layer 113 and the magnet assembly 112. When the refrigerator 121 is not working or needs to be replaced, the first thermal switch 122 and the second thermal switch 123 disconnect the cold energy transmission channel, thus preventing external cold energy from being transferred to the interior of the superconducting magnet structure 100 and preventing the superconducting magnet from overheating. In this way, it is not necessary to spend a long time cooling the radiation shielding layer 113 and the magnet assembly 112 during later use, saving time. At the same time, it can also reduce the loss of liquid helium in the magnet assembly 112 and the quenching failure of the superconducting coil 1122, reducing maintenance costs. Furthermore, the superconducting magnet structure 100 of the present invention is simple, easy to install, and highly reliable.

[0094] The present invention also provides a magnetic resonance imaging (MRI) device, including a gradient coil, a radio frequency (RF) coil, and a superconducting magnet structure 100. The superconducting magnet structure 100 has a scanning aperture, the RF coil is disposed in the scanning aperture, and the gradient coil is located between the RF coil and the superconducting magnet structure 100. The superconducting magnet structure 100 includes a cryogenic holder 110 and a cooling assembly 120. The cryogenic holder 110 includes an outer container 111, a magnet assembly 112, and a radiation shielding layer 113 coaxially arranged. The magnet assembly 112 is disposed inside the outer container 111, and the radiation shielding layer 113 is located between the outer container 111 and the magnet assembly 112. The refrigeration assembly 120 includes a refrigeration unit 121, a first thermal switch 122, and a second thermal switch 123. The refrigeration unit 121 is disposed in the outer container 111. The refrigeration unit 121 has a first cold head 1211 and a second cold head 1212. The first thermal switch 122 can connect the first cold head 1211 to the radiation shielding layer 113. The second cold head 1212 is connected to the magnet assembly 112 through the second thermal switch 123.

[0095] The superconducting magnet structure 100 in the magnetic resonance device of the present invention is the same as the superconducting magnet structure 100 in the above embodiments. The specific structure and working principle of the two are essentially the same, and will not be described in detail here. After adopting the above-mentioned superconducting magnet structure 100, the magnetic resonance device can avoid the superconducting magnet structure 100 from losing its quench, ensure the performance of the magnetic resonance device, reduce the cost of the device, and save the time for cooling the superconducting coil 1122 in later use.

[0096] In one embodiment, the first thermal switch 122 includes a first housing 1221, a first cold end 1222, and a first hot end 1223. The first housing 1221 is hollow. The first cold end 1222 and the first hot end 1223 are respectively disposed at both ends of the first housing 1221. The first cold end 1222 is connected to the first cold head 1211, and the first hot end 1223 is connected to the radiation shielding layer 113. The interior of the first housing 1221 is filled with a first cooling medium 1224 capable of gas-liquid conversion. The second thermal switch 123 includes a second housing 1231, a second cold end 1232, and a second hot end 1233. The second housing 1231 is hollow. The second cold end 1232 and the second hot end 1233 are respectively disposed at both ends of the second housing 1231. The second cold end 1232 is connected to the second cold head 1212, and the second hot end 1233 is connected to the radiation shielding layer 113. The interior of the second housing 1231 is filled with a second cooling medium 1234 capable of gas-liquid conversion.

[0097] The first thermal switch 122 and the second thermal switch 123 establish the connection and disconnection of the cold energy transmission channel between the refrigerator 121 and the superconducting magnet structure 100. When the refrigerator 121 is working, the first thermal switch 122 and the second thermal switch 123 conduct the cold energy transmission channel, which can cool the radiation shielding layer 113 and the magnet assembly 112. When the refrigerator 121 is not working or needs to be replaced, the first thermal switch 122 and the second thermal switch 123 disconnect the cold energy transmission channel, thus preventing external cold energy from being transferred to the interior of the superconducting magnet structure 100 and preventing the superconducting magnet from overheating. The structure and working principle of the first thermal switch 122 and the second thermal switch 123 have been mentioned above and will not be repeated here.

[0098] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A superconducting magnet structure, characterized in that, include: A cryogenic holder includes an outer container, a magnet assembly, and a radiation shielding layer, wherein the magnet assembly is disposed inside the outer container, and the radiation shielding layer is located between the outer container and the magnet assembly; as well as A refrigeration assembly includes a refrigeration unit, a first thermal switch and / or a second thermal switch. The refrigeration unit is disposed in the outer container. The refrigeration unit has a first cold head and a second cold head. The first thermal switch can connect the first cold head to the radiation shielding layer. The second cold head is connected to the magnet assembly through the second thermal switch. The magnet assembly includes an inner container and a superconducting coil disposed within the inner container, wherein a second thermal switch is connected to the inner container, and the inner container contains a cooling medium; or, the second thermal switch is connected to the superconducting coil. The first thermal switch is filled with a first cooling medium capable of gas-liquid conversion, and the second thermal switch is filled with a second cooling medium capable of gas-liquid conversion. When the refrigerator is working, the first thermal switch converts gas and liquid through the first cooling medium to open the cold energy transmission channel and cool the radiation shielding layer. The second thermal switch conducts gas-liquid conversion through the second cooling medium to open the cold energy transmission channel and cool the magnet assembly.

2. The superconducting magnet structure according to claim 1, characterized in that, The first thermal switch includes a first housing, a first cold end, and a first hot end. The first housing is hollow. The first cold end and the first hot end are respectively disposed at both ends of the first housing. The first cold end is connected to the first cold head, and the first hot end is connected to the radiation shielding layer. The interior of the first housing is filled with a first cooling medium capable of gas-liquid conversion.

3. The superconducting magnet structure according to claim 2, characterized in that, The second thermal switch includes a second housing, a second cold end, and a second hot end. The second housing is hollow. The second cold end and the second hot end are respectively disposed at both ends of the second housing. The second cold end is connected to the second cold head, and the second hot end is connected to the magnet assembly. The interior of the second housing is filled with a second cooling medium capable of gas-liquid conversion.

4. The superconducting magnet structure according to claim 3, characterized in that, The boiling point range of the first cooling medium is different from that of the second cooling medium.

5. The superconducting magnet structure according to claim 1, characterized in that, The first thermal switch and the second thermal switch are retractable components. When the first thermal switch is cooled, it can extend to connect the first cold head and the radiation shielding layer. When the second thermal switch is cooled, it can extend to connect the second cold head and the magnet assembly.

6. The superconducting magnet structure according to any one of claims 1 to 5, characterized in that, The number of the first thermal switches is one or more; when the number of the first thermal switches is multiple, the multiple first thermal switches are arranged at intervals. The number of the second thermal switches is one or more. When the number of the second thermal switches is multiple, the multiple second thermal switches are arranged at intervals.

7. The superconducting magnet structure according to any one of claims 1 to 5, characterized in that, The refrigeration assembly further includes a first connector and a second connector. The first connector is connected to both ends of the first thermal switch to connect the first cold head and the radiation shielding layer, respectively. The second connector is connected to both ends of the second thermal switch to connect the second cold head and the magnet assembly respectively.

8. A magnetic resonance imaging device, characterized in that, The invention includes a gradient coil, a radio frequency coil, and a superconducting magnet structure as described in any one of claims 1-7, wherein the superconducting magnet structure has a scanning aperture, the radio frequency coil is disposed in the scanning aperture, and the gradient coil is located between the radio frequency coil and the superconducting magnet structure. The superconducting magnet structure includes: A cryogenic holder includes an outer container, a magnet assembly, and a radiation shielding layer, wherein the magnet assembly is disposed inside the outer container, and the radiation shielding layer is located between the outer container and the magnet assembly; and Refrigeration components, including: A refrigeration unit is installed in the outer container; A connector for connecting the refrigerator and the magnet assembly, or for connecting the refrigerator and the radiation shielding layer; A thermal switch is connected in series with the connector. The thermal switch contains a cooling medium, and changes in the state of the cooling medium cause the thermal switch to be in an on or off mode.

9. The magnetic resonance apparatus according to claim 8, characterized in that, The thermal switch includes a first thermal switch and / or a second thermal switch; The first thermal switch includes a first housing, a first cold end, and a first hot end. The first housing is hollow. The first cold end and the first hot end are respectively disposed at both ends of the first housing. The first cold end is connected to the first cold head of the superconducting magnet structure, and the first hot end is connected to the radiation shielding layer. The interior of the first housing is filled with a first cooling medium capable of gas-liquid conversion. The second thermal switch includes a second housing, a second cold end, and a second hot end. The second housing is hollow. The second cold end and the second hot end are respectively disposed at both ends of the second housing. The second cold end is connected to the second cold head of the superconducting magnet structure, and the second hot end is connected to the radiation shielding layer. The interior of the second housing is filled with a second cooling medium capable of gas-liquid conversion.

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