Low temperature cooling device, cooling system and operation method of dry superconducting magnet

Abstract

The present application provides a low-temperature cooling device, a cooling system and an operating method of a dry superconducting magnet, which belongs to the field of cooling technology of dry superconducting magnets. The gas buffer tank of the low-temperature cooling device is connected to the cold storage container, and the gas buffer tank and the cold storage container together form a closed cavity, so that the gas in the gas buffer tank can enter the cold storage container to be cooled into a solid refrigerant, and the solid refrigerant sublimated in the cold storage container can enter the gas buffer tank. The refrigerator is located outside the cold storage container and is configured to cool the gas in the cold storage container into a solid refrigerant and to cool the dry superconducting magnet; the cold storage container is configured to cool the dry superconducting magnet when the solid refrigerant sublimates. When the refrigerator stops working, the heating rate of the dry superconducting magnet can be slowed down, and the time for the dry superconducting magnet to heat up to the temperature threshold can be extended to avoid the dry superconducting magnet from quenching when the refrigerator is shut down, thereby increasing the stability and flexibility of the system.

Description

Technical Field

[0001] The present application relates to the technical field of cooling of dry superconducting magnets, and in particular to a low-temperature cooling device, a cooling system and an operating method thereof for a dry superconducting magnet. Background Art

[0002] With the rising price of liquid helium and the scarcity of helium resources, different methods are being tried in various scenarios to reduce the use of helium and improve the efficiency of helium use. The common cooling method for superconducting magnets is to use liquid helium to soak the superconducting coils. Usually, tens to thousands of liters of liquid helium are used to meet the soaking requirements. In order to improve the efficiency of helium use and reduce dependence on liquid helium, dry magnets are gradually being used in various devices including magnetic resonance systems, NMR systems, and scientific instruments. The so-called dry magnet refers to the use of conduction cooling to transfer the coldness of the refrigerator to the magnet coil to be cooled. After the coil is cooled to the expected temperature, it will achieve a superconducting state and meet the working requirements. Dry magnets do not require a large amount of liquid helium soaking, only need to turn on the refrigerator to cool. At the same time, in the case of rewarming, helium will not escape due to the rising temperature of the cold medium.

[0003] The dry magnet solution also brings corresponding problems. During the operation of the equipment, it is inevitable that there will be water outages, power outages, and refrigerator shutdowns, and the magnet coil will heat up. If such a situation is detected, the magnet coil can actively reduce the field to a safe value. However, due to the small heat capacity of the magnet coil at low temperatures, after the refrigerator system stops working, the magnet coil will heat up quickly and will quench after exceeding the threshold, and the magnet coil can no longer actively reduce the field to a safe value. Summary of the invention

[0004] The purpose of the present application is to provide a low-temperature cooling device, a cooling system and an operating method of a dry superconducting magnet, which can slow down the heating rate of the dry superconducting magnet when the refrigerator stops working, prolong the time for the dry superconducting magnet to heat up to the temperature threshold, avoid the dry superconducting magnet from quenching when the refrigerator stops working, and increase the stability and flexibility of the system.

[0005] In a first aspect, the present application provides a low-temperature cooling device for a dry superconducting magnet, comprising a gas buffer tank, a cold storage container, and a refrigerator. The gas buffer tank is connected to the cold storage container, and the gas buffer tank and the cold storage container together form a closed cavity, so that the gas in the gas buffer tank can enter the cold storage container to be cooled into a solid refrigerant, and the solid refrigerant sublimated in the cold storage container can enter the gas buffer tank. The refrigerator is located outside the cold storage container and is configured to cool the gas in the cold storage container into a solid refrigerant and to cool the dry superconducting magnet; the cold storage container is configured to cool the dry superconducting magnet when the solid refrigerant sublimates.

[0006] When the refrigerator is working, the cold energy generated by the refrigerator can be used to cool the dry superconducting magnet and the cold storage container. The air pressure in the cold storage container drops, and the gas in the gas buffer tank enters the cold storage container. Since the temperature in the cold storage container is relatively low, the gas entering the cold storage container can be cooled into a solid state. When the refrigerator stops working, although the refrigerator no longer generates cold energy, the solid refrigerant in the cold storage container will sublime into gas, which will enter the gas buffer tank again. At the same time, the solid refrigerant absorbs a large amount of heat when it sublimates, which reduces the temperature of the cold storage container (slows down the heating rate of the cold storage container), which can also slow down the heating rate of the dry superconducting magnet and prolong the time for the dry superconducting magnet to heat up to the temperature threshold, thus avoiding the quenching of the dry superconducting magnet when the refrigerator stops working, and increasing the stability and flexibility of the system. At the same time, the cold storage container and the gas buffer tank together form a closed cavity, and the cold head of the refrigerator does not need to be extended into the cold storage container, avoiding the problem of performance degradation of the cold head after the refrigerant solidifies at low temperature; and the gas is in a closed circulation cavity, reducing maintenance costs and making the device simpler.

[0007] In a possible implementation, the gas buffer tank is connected to the cold storage container via a pipeline, and a temperature sensor and a heater are provided outside the pipeline near the cold storage container.

[0008] If too much solid refrigerant is produced in the cold storage container, the pipeline may be blocked. Therefore, a temperature sensor and a heater are set at one end of the pipeline close to the cold storage container. On the one hand, if the temperature sensor detects that the temperature in the pipeline is too low, it means that there may be solid refrigerant in the pipeline, and the heater is turned on to heat the solid refrigerant to sublime into gas; if the temperature sensor detects that the temperature in the pipeline rises, it means that the solid refrigerant in the pipeline has turned into gas, and the heater is turned off to avoid clogging of the pipeline.

[0009] In a possible embodiment, the pipeline includes a first pipeline and a second pipeline, the first pipeline and the second pipeline are respectively connected to the gas buffer tank and the cold storage container, the first pipeline is provided with a first one-way valve so that the gas in the gas buffer tank can enter the cold storage container, and the second pipeline is provided with a second one-way valve so that the gas in the cold storage container can enter the gas buffer tank.

[0010] The gas in the gas buffer tank enters the cold storage container from the first pipeline, and the gas in the cold storage container enters the gas buffer tank from the second pipeline, forming a circulating closed space.

[0011] In a possible implementation, the refrigerator includes a primary cold head, a secondary cold head, a cold shield and a cold conduction belt, the primary cold head is connected to the cold shield, the cold shield is spaced apart from the cold storage container, the secondary cold head is connected to the cold conduction belt, and the cold conduction belt is connected to the outer shell of the cold storage container.

[0012] The primary cold head, secondary cold head, cold shield and cold conduction belt are all located outside the cold storage container, which can avoid the problem of performance degradation after the refrigerant solidifies at low temperatures. In addition, the primary cold head and cold shield can be used for pre-cooling, and then the secondary cold head and cold conduction belt can be used for further cooling, so that the temperature inside the cold storage container is lower and the gas can be cooled into solid refrigerant.

[0013] In a possible implementation, the cold shield wraps the cold storage container and the cold conductive belt; the cold shield is also used to wrap the dry superconducting magnet.

[0014] The above-mentioned setting method of the cold shield can pre-cool the cold storage container, the cold conduction belt and the dry superconducting magnet, so as to lower the temperature in the cold storage container and achieve a better cooling effect on the dry superconducting magnet.

[0015] In a possible implementation, the cooling belt is a metal belt, which can make it easier to cool the gas in the cold storage container into a solid state and also make it easier to refrigerate the dry superconducting magnet.

[0016] In a possible implementation, a heat exchange component for increasing the heat exchange area is provided in the cold storage container, so that the heat exchange effect between the gas in the cold storage container and the cold can be better, so that the gas can be quickly condensed into a solid refrigerant.

[0017] In a possible implementation, the heat exchange element is a foam metal, which is disposed in the cold storage container and connected to the inner wall of the cold storage container.

[0018] There are many small holes in the foam metal, and the gas can easily enter the foam metal; at the same time, the cold energy on the cooling belt is also transferred to the foam metal, and the gas and the cold energy exchange heat in the holes of the foam metal, so that the gas can quickly condense into solid refrigerant.

[0019] On the one hand, the connection between the foam metal and the cold storage container can be made more secure, and the thermal resistance at the connection interface can be smaller; on the other hand, the cold energy of the cooling belt can be more easily transferred to the foam metal through the metal belt to exchange heat with the gas.

[0020] In a second aspect, the present application provides a low-temperature cooling system for a dry superconducting magnet, comprising: a dry superconducting magnet and the above-mentioned low-temperature cooling device, wherein the dry superconducting magnet is located outside a cold storage container and is configured to be able to exchange heat with the cold storage container.

[0021] In a third aspect, the present application provides an operating method of the above-mentioned low-temperature cooling system, including a refrigerator operating mode and a refrigerator shutdown mode. The refrigerator operating mode includes: the refrigerator generates cold energy during operation, and the cold energy cools the cold storage container, so that the gas entering the cold storage container from the gas buffer tank is cooled into a solid state, and the dry superconducting magnet is cooled at the same time. The refrigerator shutdown mode includes: the solid refrigerant in the cold storage container sublimates into a gas and enters the gas buffer tank, and absorbs heat to slow down the heating rate in the cold storage container, thereby slowing down the heating rate of the dry superconducting magnet.

[0022] The dry superconducting magnet can be cooled by a refrigerator; at the same time, when the refrigerator is shut down, the heating rate of the dry superconducting magnet can be slowed down, and the time for the dry superconducting magnet to heat up to the temperature threshold can be prolonged, thereby avoiding the dry superconducting magnet from quenching when the refrigerator is shut down, and increasing the stability and flexibility of the system.

[0023] In a possible implementation, the gas in the gas buffer tank is nitrogen and / or neon. Nitrogen and neon have large specific heat capacities, and when the refrigerator is shut down, the heating rate of the dry superconducting magnet can be further slowed down. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, without paying any creative work, other related drawings can be obtained based on these drawings and they also belong to the protection scope of the present application.

[0025] Figure 1 A schematic diagram of a low-temperature cooling system for a dry superconducting magnet provided in an embodiment of the present application;

[0026] Figure 2 A schematic diagram of the structure of a cold storage container provided in an embodiment of the present application.

[0027] Icons: 100-dry superconducting magnet; 210-gas buffer tank; 220-cold storage container; 230-refrigeration machine; 241-first pipeline; 242-second pipeline; 243-temperature sensor; 244-heater; 231-first cold head; 232-second cold head; 233-cold shield; 234-cooling belt; 250-heat exchange component; 251-foam metal. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0029] Figure 1 Schematic diagram of a low temperature cooling system for a dry superconducting magnet provided in an embodiment of the present application. Figure 1 In the embodiment of the present application, the cryogenic cooling system of the dry superconducting magnet includes: a dry superconducting magnet 100 and a cryogenic cooling device for the dry superconducting magnet, and the cryogenic cooling device for the dry superconducting magnet is used to cool the dry superconducting magnet 100 to keep it in a superconducting state.

[0030] In the embodiment of the present application, the low temperature cooling device of the dry superconducting magnet includes a gas buffer tank 210, a cold storage container 220 and a refrigerator 230. The refrigerator 230 is located outside the cold storage container 220 and is configured to cool the gas in the cold storage container 220 into a solid refrigerant, and to cool the dry superconducting magnet 100 to keep it in a superconducting state; the cold storage container 220 is configured to cool the dry superconducting magnet 100 when the solid refrigerant sublimates (the dry superconducting magnet 100 is located outside the cold storage container 220). The gas buffer tank 210 is connected to the cold storage container 220, and the gas buffer tank 210 and the cold storage container 220 jointly form a closed cavity, so that the gas in the gas buffer tank 210 can enter the cold storage container 220 to be cooled into a solid refrigerant and the solid refrigerant sublimated in the cold storage container 220 can enter the gas buffer tank 210. The cold storage container 220 is configured to cool the gas in the cold storage container 220.

[0031] The operation method of the above-mentioned low-temperature cooling system includes a refrigerator 230 working mode and a refrigerator 230 shutdown mode. The refrigerator 230 working mode includes: the refrigerator 230 generates cold energy, which can be used to cool the dry superconducting magnet 100, and the cold energy can also be used to cool the cold storage container 220. The air pressure in the cold storage container 220 decreases, and the gas in the gas buffer tank 210 enters the cold storage container 220. Since the temperature in the cold storage container 220 is relatively low, the gas entering the cold storage container 220 can be cooled into a solid state. At the same time, the cold energy in the cold storage container 220 can also be used to cool the dry superconducting magnet 100.

[0032] The shutdown mode of the refrigerator 230 includes: the solid refrigerant in the cold storage container 220 sublimates into gas and enters the gas buffer tank 210, and absorbs heat to slow down the temperature rise rate in the cold storage container 220, thereby slowing down the temperature rise rate of the dry superconducting magnet 100. When the refrigerator 230 stops, although the refrigerator 230 no longer generates cold, the solid refrigerant in the cold storage container 220 will sublimate into gas, which will enter the gas buffer tank 210. At the same time, the solid refrigerant absorbs a large amount of heat when it sublimates, so that the temperature of the cold storage container 220 is reduced (the temperature rise rate of the cold storage container 220 is slowed down), which can also slow down the temperature rise rate of the dry superconducting magnet 100, prolong the time for the dry superconducting magnet 100 to heat up to the temperature threshold, avoid the dry superconducting magnet 100 from quenching when the refrigerator 230 is shut down, and increase the stability and flexibility of the system. At the same time, the cold storage container 220 and the gas buffer tank 210 together form a closed cavity, and the cold head of the refrigerator 230 does not need to extend into the cold storage container 220, avoiding the problem of performance degradation of the cold head after the refrigerant solidifies at low temperatures; and the gas is in a closed circulation cavity, reducing maintenance costs and making the device simpler.

[0033] In the embodiment of the present application, the gas in the gas buffer tank 210 may be nitrogen and / or neon (nitrogen, neon, or a mixture of nitrogen and neon), nitrogen (the specific heat capacity of nitrogen is 0.2 J / cm 3 .K) and neon (the specific heat capacity of neon is 0.5 J / cm 3 .K) has a large specific heat capacity, and when the refrigerator 230 is shut down, the heating rate of the dry superconducting magnet 100 can be further slowed down.

[0034] In other embodiments, the gas in the gas buffer tank 210 may also be other gases with larger specific heat capacity, and the present application does not make any limitation thereto. As long as the gas can prolong the time for the dry superconducting magnet 100 to heat up to the temperature threshold when the refrigerator 230 is shut down, the gas is within the protection scope of the present application.

[0035] In order to make good use of the gas buffer tank 210, a safety valve and a discharge / filling valve are provided on the gas buffer tank 210 to fill the gas buffer tank 210 with gas or discharge the gas from the gas buffer tank 210, and to make the use of the gas buffer tank 210 safer.

[0036] In the embodiment of the present application, the gas buffer tank 210 can be used in an air environment or in a vacuum environment, which is not limited in the present application.

[0037] In the embodiment of the present application, the gas buffer tank 210 is connected to the cold storage container 220 through a pipeline, and a temperature sensor 243 and a heater 244 are provided outside the pipeline near the cold storage container 220.

[0038] If too much solid refrigerant is generated in the cold storage container 220, the pipeline may be blocked. Therefore, a temperature sensor 243 and a heater 244 are set at one end of the pipeline close to the cold storage container 220. On the one hand, if the temperature sensor 243 detects that the temperature in the pipeline is too low, it means that there may be solid refrigerant in the pipeline, and the heater 244 is turned on to heat the solid refrigerant to sublime into gas; if the temperature sensor 243 detects that the temperature in the pipeline rises, it means that the solid refrigerant in the pipeline has turned into gas, and the heater 244 is turned off to avoid clogging of the pipeline.

[0039] In one embodiment, there are two pipelines, including a first pipeline 241 and a second pipeline 242. The first pipeline 241 and the second pipeline 242 are respectively connected to the gas buffer tank 210 and the cold storage container 220. The first pipeline 241 is provided with a first one-way valve so that the gas in the gas buffer tank 210 can enter the cold storage container 220. The second pipeline 242 is provided with a second one-way valve so that the gas in the cold storage container 220 can enter the gas buffer tank 210.

[0040] The gas in the gas buffer tank 210 enters the cold storage container 220 from the first pipe 241, and the gas in the cold storage container 220 enters the gas buffer tank 210 from the second pipe 242, forming a closed circulation space. A temperature sensor 243 and a heater 244 are provided on the outer wall of the first pipe 241 and the second pipe 242 at one end close to the cold storage container 220, so as to avoid the blockage of the first pipe 241 and the second pipe 242 through the cooperation of the two temperature sensors 243 and the two heaters 244.

[0041] In another embodiment, the pipeline can also be one. When the refrigerator 230 is working, the gas in the gas buffer tank 210 enters the cold storage container 220 through the pipeline; when the refrigerator 230 is stopped, the gas in the cold storage container 220 enters the gas buffer tank 210 through the same pipeline, so that the gas buffer tank 210 and the cold storage container 220 form a sealed circulation space together.

[0042] In an embodiment of the present application, the refrigerator 230 includes a primary cold head 231, a secondary cold head 232, a cold shield 233 and a cold conduction belt 234. The primary cold head 231 is connected to the cold shield 233, the cold shield 233 is spaced apart from the cold storage container 220, the secondary cold head 232 is connected to the cold conduction belt 234, and the cold conduction belt 234 is connected to the outer shell of the cold storage container 220.

[0043] The primary cold head 231, the secondary cold head 232, the cold shield 233 and the cold conduction belt 234 are all located outside the cold storage container 220, which can avoid the problem of cold head performance attenuation after the refrigerant solidifies at low temperatures. And the primary cold head 231 and the cold shield 233 (the temperature of the cold shield 233 is about 50K) can be used for pre-cooling, and then the secondary cold head 232 and the cold conduction belt 234 (the temperature of the cold conduction belt 234 is about 4K) can be used for further cooling, so that the temperature inside the cold storage container 220 is lower, and the gas can be cooled into a solid refrigerant.

[0044] The cold shield 233 wraps the cold storage container 220, the cold conducting belt 234 and the dry superconducting magnet 100, so as to reduce the heat load in the low temperature area.

[0045] After the cold storage container 220 and the gas in the cold storage container 220 are cooled by the refrigerator 230 (the cold conduction belt 234 of the refrigerator 230), the dry superconducting magnet 100 is cooled at the same time. In order to enable the cold storage container 220 to cool the dry superconducting magnet 100 better, the thermal resistance between the cold storage container 220 and the dry superconducting magnet 100 is smaller. Optionally, the outer wall of the shell of the cold storage container 220 is made of metal (copper (the specific heat capacity of copper is 7.65x10 -3 J / cm 3 .K) or aluminum) is connected to the dry superconducting magnet 100.

[0046] Optionally, the cooling belt is a metal belt. It can make it easier to cool the gas in the cold storage container into a solid state, and it can also make it easier to refrigerate the dry superconducting magnet. For example, the cooling belt 234 can be a copper belt or an aluminum belt. High-purity copper belt or aluminum belt is used to achieve flexible connection (5N or above) and high heat transfer coefficient, and at the connection interface, argon arc welding is used to minimize contact thermal resistance.

[0047] In order to enable the gas entering the cold storage container 220 to be quickly cooled into a solid state in the cold storage container 220 . Figure 2 This is a schematic diagram of the structure of the cold storage container 220 provided in the embodiment of the present application. Figure 1 and Figure 2 Optionally, a heat exchange element 250 for increasing the heat exchange area is provided in the cold storage container 220.

[0048] In the embodiment of the present application, the heat exchange element 250 is a foam metal 251 (eg, foam copper or foam aluminum). The foam metal 251 is disposed in the cold storage container 220 and connected to the inner wall of the cold storage container 220 .

[0049] There are many small holes in the foam metal 251, and the gas can easily enter the foam metal 251; at the same time, the cold energy on the cooling belt 234 is also transferred to the foam metal 251, and the gas and the cold energy exchange heat at the holes of the foam metal 251, so that the gas can quickly condense into a solid refrigerant.

[0050] Optionally, the foam metal 251 can be brazed or soldered to the inner wall of the cold storage container 220. The shape of the foam metal 251 can be processed arbitrarily according to the shape of the cold storage container 220 to increase the heat exchange area between the gas and the cold storage container 220.

[0051] In another embodiment, the heat exchange element 250 may also be a fin-type heat exchange structure, which is also soldered or brazed to the inner wall of the cold storage container 220 to quickly cool the gas into a solid state.

[0052] The beneficial effects of the low temperature cooling system of the dry superconducting magnet and the operating method thereof provided in the embodiments of the present application include:

[0053] (1) When the refrigerator 230 is working, the dry superconducting magnet 100 can be cooled to be in a superconducting state, and the gas in the cold storage container 220 can be cooled into a solid refrigerant. When the refrigerator 230 is stopped, the solid refrigerant sublimates to slow down the heating rate of the cold storage container 220, which can slow down the heating rate of the dry superconducting magnet 100 and extend the time for the dry superconducting magnet 100 to heat up to the temperature threshold, thereby avoiding the dry superconducting magnet 100 from quenching when the refrigerator 230 is stopped, thereby increasing the stability and flexibility of the system.

[0054] (2) The cold storage container 220 and the gas buffer tank 210 together form a closed cavity. The cold head of the refrigerator 230 does not need to be extended into the cold storage container 220, thereby avoiding the problem of performance degradation of the cold head after the refrigerant solidifies at low temperatures. The gas is in a closed circulation cavity, which reduces maintenance costs and makes the device simpler.

[0055] (3) The foam metal 251 is arranged in the cold storage container 220, so that the gas in the cold storage container 220 can be quickly cooled into a solid state, so as to further avoid the dry superconducting magnet 100 from quenching when the refrigerator 230 is shut down, thereby increasing the stability and flexibility of the system.

[0056] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

Claims

1. A low temperature cooling device for a dry superconducting magnet, characterized in that: include: Gas buffer tanks, cold storage vessels and refrigerators; The gas buffer tank is in communication with the cold storage container, and the gas buffer tank and the cold storage container together form a closed cavity, so that the gas in the gas buffer tank can enter the cold storage container to be cooled into a solid refrigerant, and the sublimated solid refrigerant in the cold storage container can enter the gas buffer tank; The refrigerator is located outside the cold storage container and is configured to cool the gas in the cold storage container into the solid refrigerant and to cool the dry superconducting magnet; the cold storage container is configured to cool the dry superconducting magnet when the solid refrigerant sublimates; The gas buffer tank is connected to the cold storage container through a pipeline, and a temperature sensor and a heater are arranged outside the pipeline near the cold storage container; The refrigerator includes a primary cold head, a secondary cold head, a cold shield and a cold conduction belt, the primary cold head is connected to the cold shield, the cold shield is spaced apart from the cold storage container, the secondary cold head is connected to the cold conduction belt, and the cold conduction belt is connected to the outer shell of the cold storage container.

2. The cryogenic cooling device according to claim 1, characterized in that: The pipeline includes a first pipeline and a second pipeline, the first pipeline and the second pipeline are respectively connected to the gas buffer tank and the cold storage container, the first pipeline is provided with a first one-way valve so that the gas in the gas buffer tank can enter the cold storage container, and the second pipeline is provided with a second one-way valve so that the gas in the cold storage container can enter the gas buffer tank.

3. The cryogenic cooling device according to claim 1, characterized in that: The cold shield wraps the cold storage container and the cold conduction belt; the cold shield is also used to wrap the dry superconducting magnet.

4. The cryogenic cooling device according to claim 3, characterized in that: The cooling belt is a metal belt.

5. The cryogenic cooling device according to any one of claims 1 to 4, characterized in that: A heat exchange component for increasing the heat exchange area is arranged in the cold storage container.

6. The cryogenic cooling device according to claim 5, characterized in that: The heat exchange element is a foam metal, which is arranged in the cold storage container and connected to the inner wall of the cold storage container.

7. A low temperature cooling system for a dry superconducting magnet, characterized in that: include: A dry superconducting magnet and a low-temperature cooling device according to any one of claims 1 to 6, wherein the dry superconducting magnet is located outside the cold storage container and is configured to be able to exchange heat with the cold storage container.

8. A method for operating a low temperature cooling system according to claim 7, characterized in that: Including refrigerator working mode and refrigerator shutdown mode: The refrigerator operation mode includes: the refrigerator generates cold energy when working, and the cold energy cools the cold storage container, so that the gas entering the cold storage container from the gas buffer tank is cooled into a solid state, and the dry superconducting magnet is cooled at the same time; The refrigerator shutdown mode includes: the solid refrigerant in the cold storage container sublimates into gas and enters the gas buffer tank, and absorbs heat to slow down the temperature rise rate in the cold storage container, thereby slowing down the temperature rise rate of the dry superconducting magnet.

9. The method for operating a low temperature cooling system according to claim 8, characterized in that: The gas in the gas buffer tank is nitrogen and / or neon.

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