Precooling method for a cryostat and a superconducting magnet

Abstract

The application relates to a thermostat and a precooling method of a superconducting magnet, which is applied to a dewar flask, the dewar flask comprising a first vacuum layer, the first vacuum layer comprising a cold screen structure, and the precooling method comprising the following steps: when filling a refrigerant and / or cooling the cold screen structure, reducing the vacuum degree of the first vacuum layer. In the precooling method of the thermostat and the superconducting magnet, in order to improve the precooling cooling efficiency of the thermostat, the first vacuum layer of the vacuum layer can be broken to be handled, and when the first vacuum layer itself has a specified design vacuum degree, the broken handling breaks the original design vacuum degree of the first vacuum layer, reduces the vacuum degree of the first vacuum layer to below the original design vacuum degree, and maintains the reduced vacuum degree at a suitable target vacuum value. The reduced vacuum degree can accelerate the convection cooling of the refrigerant in the thermostat on the cold screen structure, effectively matches the cooling process of the cold screen structure, and improves the cooling speed.

Description

Technical Field

[0001] This invention relates to the field of cryogenic equipment technology, and in particular to a precooling method for a thermostat and a superconducting magnet. Background Technology

[0002] In cryogenic equipment systems, in order to reduce the radiative heat leakage of the thermostat, the temperature of the cold shield structure inside the thermostat needs to be reduced to the target temperature value as soon as possible during the pre-cooling process to weaken the radiative heat leakage of the thermostat.

[0003] Currently, the cold shield structure is usually placed in the vacuum jacket of the thermostat. When the thermostat is pre-cooled by filling it with refrigerant (such as liquid nitrogen or liquid helium), the vacuum environment in the vacuum jacket of the thermostat will inhibit the low-temperature convection in that space, thereby reducing the cooling rate of the cold shield structure. Moreover, the higher the vacuum level of the vacuum environment, the more obvious the low-temperature convection effect in that space, and the lower the cooling rate of the cold shield structure. This results in a very long pre-cooling time for the cold shield structure, which can last for several days or even more than ten days, seriously affecting work efficiency. Summary of the Invention

[0004] Therefore, it is necessary to provide a pre-cooling method for the thermostat and superconducting magnet to address the technical problem of long pre-cooling time for the cold shield structure in the thermostat.

[0005] This invention provides a pre-cooling method for a thermostat, applied to a Dewar flask, wherein the Dewar flask includes a first vacuum jacket, and the first vacuum jacket includes a cold shield structure. The pre-cooling method includes the following steps:

[0006] When refrigerant is injected and / or the cold shield structure is cooled, the vacuum level of the first vacuum interlayer is reduced.

[0007] In one embodiment, after the refrigerant is injected and / or the cold shield structure is cooled, the vacuum level of the first vacuum interlayer is increased.

[0008] In one embodiment, reducing the vacuum level of the first vacuum interlayer includes:

[0009] The refrigerant is injected into the first vacuum interlayer.

[0010] In one embodiment, the cold screen structure includes a second vacuum interlayer, within which a cooling component is included;

[0011] First, refrigerant is filled into the refrigeration component, and then the vacuum level of the first vacuum interlayer is reduced, thereby using the refrigeration component to lower the temperature of the cold screen structure; or, the vacuum level of the first vacuum interlayer is reduced first, and then refrigerant is filled into the refrigeration component, thereby using the refrigeration component to lower the temperature of the cold screen structure.

[0012] In one embodiment, reducing the vacuum level of the first vacuum interlayer includes:

[0013] Reduce the vacuum level of the first vacuum interlayer to the target vacuum value.

[0014] In one embodiment, the target vacuum value is 5 x 10⁻⁶. -4 KPa to 3x10 -2 Between kPa.

[0015] In one embodiment, different temperatures of the cold screen structure correspond to different target vacuum values.

[0016] In one embodiment, a magnet structure is provided in the first vacuum interlayer of the Dewar flask.

[0017] In one embodiment, the refrigerant is liquid helium or helium gas.

[0018] The present invention also provides a precooling method for a superconducting magnet, including the precooling method for the thermostat.

[0019] In the aforementioned pre-cooling method for the thermostat and superconducting magnet, to improve the pre-cooling efficiency of the thermostat, the first vacuum interlayer of the vacuum layer can be evacuated. Assuming the first vacuum interlayer already has a predetermined design vacuum level, evacuation breaks the original design vacuum level, reducing it below the original design level while maintaining a suitable target vacuum value. The reduced vacuum level accelerates the convective cooling of the cold screen structure by the refrigerant within the thermostat, effectively matching the cooling process of the cold screen structure and increasing the cooling speed. Once the cold screen structure temperature drops to the target temperature, the pre-cooling operation is complete. At this point, a low vacuum environment is no longer needed to assist in the cooling process, so the vacuum layer can be evacuated again to restore the vacuum level of the first vacuum interlayer to its original design level. Throughout this process, by adjusting the vacuum level of the first vacuum interlayer, the pre-cooling process of the cold screen structure can be flexibly matched, improving the pre-cooling efficiency. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the thermostat provided in one embodiment of the present invention.

[0021] Icon labels:

[0022] 100. Vacuum inner cylinder; 200. Vacuum outer cylinder; 300. Cold screen inner cylinder; 400. Cold screen outer cylinder; 500. Low temperature inner cylinder; 600. Low temperature outer cylinder; 700. Refrigerant. Detailed Implementation

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] See Figure 1 As shown, one embodiment of the present invention provides a pre-cooling method for a thermostat, applied to a Dewar flask. The Dewar flask includes a first vacuum jacket containing a cold shield structure. The pre-cooling method includes the following steps: reducing the vacuum level of the first vacuum jacket during the injection of refrigerant 700 and / or cooling of the cold shield structure. A magnetic structure may be provided in the first vacuum jacket of the Dewar flask. The refrigerant 700 can be a liquid or a gas. It should be noted that the refrigerant 700 may convert between gas and liquid states at different stages of the refrigeration cycle. Those skilled in the art can select a suitable refrigerant according to their needs; no limitation is made here.

[0030] It should be noted that the Dewar flask has a vacuum inner cylinder 100 and a vacuum outer cylinder 200. The vacuum inner cylinder 100 and the vacuum outer cylinder 200 can be used to form a first vacuum interlayer of the Dewar flask. The first vacuum interlayer has an opening. Gas can be filled into the first vacuum interlayer or the gas in the first vacuum interlayer can be discharged from the opening. The vacuum degree of the first vacuum interlayer can be controlled by filling and discharging the gas in the first vacuum interlayer. Discharging the gas in the first vacuum interlayer and reducing the vacuum degree of the first vacuum interlayer can be regarded as a venting process of the first vacuum interlayer.

[0031] To improve the pre-cooling efficiency of the thermostat, when injecting refrigerant 700 or directly cooling the cold screen structure, the first vacuum interlayer of the vacuum layer can be punctured. Assuming that the first vacuum interlayer itself has a specified original design vacuum level, the puncture treatment is equivalent to breaking the original design vacuum level of the first vacuum interlayer, reducing the vacuum level of the first vacuum interlayer to below the original design vacuum level, and maintaining it at a suitable target vacuum value. The reduced vacuum level can accelerate the convective cooling of the cold screen structure by the refrigerant 700 in the thermostat, effectively matching the cooling process of the cold screen structure and improving the cooling speed.

[0032] Since the low vacuum environment is mainly used to accelerate the convective cooling of the cold screen structure by the refrigerant 700 in the thermostat, thereby assisting in the pre-cooling process of the cold screen structure, in one embodiment, after the refrigerant 700 is filled and the cold screen structure is cooled, the vacuum level of the first vacuum jacket can be increased. Specifically, after the temperature of the cold screen structure drops to the target temperature value, the pre-cooling operation of the cold screen structure can be completed. At this time, the low vacuum environment is no longer needed to assist in the cooling operation of the cold screen structure. Therefore, the opening of the first vacuum jacket can be used to evacuate the first vacuum jacket to restore the vacuum level of the first vacuum jacket to the original design vacuum level, ensuring that the product has the original characteristic requirements. In the entire process of controlling the vacuum level in the first vacuum jacket from the original design vacuum level to the low vacuum level and then from the low vacuum level back to the original design vacuum level, the pre-cooling method can flexibly match the pre-cooling process of the cold screen structure by adjusting the vacuum level of the first vacuum jacket at appropriate times, thereby improving the efficiency of pre-cooling.

[0033] There are various ways to reduce the vacuum level of the first vacuum interlayer. For example, in one embodiment, the vacuum level of the first vacuum interlayer can be reduced by injecting the refrigerant 700 into the first vacuum interlayer. The refrigerant 700 can be liquid helium or helium gas, etc. Those skilled in the art can select a suitable refrigerant 700 to carry out the cooling operation according to the requirements, and there is no limitation here. Therefore, when the refrigerant 700 such as liquid helium or helium gas is filled into the first vacuum interlayer, the refrigerant 700 can exchange heat with the cold screen structure, thereby absorbing the heat of the cold screen structure and transferring it to the outside for dissipation. After the temperature of the cold screen structure is reduced to the target temperature value, the pre-cooling and cooling of the cold screen structure can be achieved.

[0034] The refrigerant 700 can be directly or indirectly filled into the first vacuum interlayer, as long as it allows for contact heat exchange with the cold shield structure using the refrigerant 700, achieving cooling of the cold shield structure. For example, see [reference needed]. Figure 1As shown, based on the thermostat structure, in one embodiment, the cold shield structure may further include a second vacuum interlayer. Since the cold shield structure is located in the first vacuum interlayer, the second vacuum interlayer is also equivalent to being located in the first vacuum interlayer. The second vacuum interlayer may include a refrigeration component, which can perform refrigeration operations. Therefore, based on the thermostat structure, refrigerant 700 can be filled in the refrigeration component, thereby achieving ground filling of refrigerant 700 in the middle of the first vacuum interlayer.

[0035] Furthermore, the order of filling the refrigerant 700 and reducing the vacuum level of the environment is not limited, as long as the reduced vacuum level can help improve the pre-cooling efficiency of the cold screen structure. For example, in one embodiment, the refrigerant 700 can be filled into the refrigeration component first, and then the vacuum level of the first vacuum interlayer can be reduced to reduce the temperature of the cold screen structure. Alternatively, the vacuum level of the first vacuum interlayer can be reduced first, and then the refrigerant 700 can be filled into the refrigeration component to reduce the temperature of the cold screen structure.

[0036] It should be noted that the cold shield structure has a cold shield inner cylinder 300 and a cold shield outer cylinder 400. The cold shield inner cylinder 300 and the cold shield outer cylinder 400 can be used to form a second vacuum interlayer. The refrigeration component has a low-temperature inner cylinder 500 and a low-temperature outer cylinder 600. The low-temperature inner cylinder 500 and the low-temperature outer cylinder 600 can be used to fill refrigerant 700.

[0037] The reduction in ambient vacuum can accelerate the convective cooling of the cold shield structure by the refrigerant 700 within the thermostat, thus improving the pre-cooling efficiency of the cold shield structure. This efficiency is also related to the degree of vacuum reduction. Those skilled in the art can adjust the degree of vacuum reduction according to actual needs to obtain the corresponding pre-cooling efficiency. For example, in one embodiment, when reducing the vacuum level of the first vacuum jacket, a target vacuum value can be set. When the operator performs vacuum breaking, the vacuum level of the first vacuum jacket can be reduced from the original design vacuum level to the target vacuum value according to standard requirements. The target vacuum value can be selected as 5 x 10⁻⁶. -4 KPa to 3x10 -2 Between kPa, for example, the target vacuum value can be 5 x 10. -4 KPa, 6x10 - 4 KPa, 7x10 -4 kPa, 8x10 -4 KPa, 9x10 -4 KPa, 1x10 -3 KPa, 2x10 -3 KPa, 3x10 -3 KPa, 4x10-3 KPa, 5x10 - 3 KPa, 6x10 -3 KPa, 7x10 -3 kPa, 8x10 -3 KPa, 9x10 -3 KPa, 1x10 -2 KPa, 2x10 -2 KPa, 3x10 -2 KPa, etc., can be set according to the needs of those skilled in the art, and are not limited here. Therefore, when the cold screen structure needs to be reduced to different temperatures, those skilled in the art can select different target vacuum values ​​to achieve standardized pre-cooling and cooling operations and improve work efficiency.

[0038] This invention also provides a pre-cooling method for a superconducting magnet, including the pre-cooling method for the thermostat. Therefore, when it is necessary to pre-cool the superconducting magnet, the ambient vacuum level can be reduced to break the vacuum in the first vacuum interlayer. Assuming that the first vacuum interlayer of the thermostat itself has a predetermined original design vacuum level, the breaking process is equivalent to breaking the original design vacuum level of the first vacuum interlayer, reducing the vacuum level of the first vacuum interlayer to below the original design vacuum level, and maintaining it at a suitable target vacuum value. The reduced vacuum level can accelerate the convective cooling of the cold screen structure by the refrigerant 700 in the thermostat, effectively matching the cooling process of the cold screen structure and improving the cooling speed.

[0039] Once the temperature of the cold screen structure drops to the target temperature, the pre-cooling operation can be completed. At this point, a low-vacuum environment is no longer needed to assist in the cooling operation. Therefore, the opening in the first vacuum interlayer can be used to evacuate the first vacuum interlayer, restoring its vacuum level to the original design vacuum level. This ensures that the product retains its original performance requirements. Throughout the process of controlling the vacuum level in the first vacuum interlayer from the original design vacuum level to a low vacuum level and then back to the original design vacuum level, the pre-cooling method can flexibly match the pre-cooling process of the cold screen structure by selectively adjusting the vacuum level of the first vacuum interlayer at appropriate times, thereby improving the efficiency of pre-cooling.

[0040] 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.

[0041] 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 precooling method for a thermostat, applied to a Dewar flask, the Dewar flask comprising a vacuum inner cylinder (100), a vacuum outer cylinder (200), a low-temperature inner cylinder (500), and a low-temperature outer cylinder (600). The space between the low-temperature inner cylinder (500) and the low-temperature outer cylinder (600) is used to fill refrigerant; The vacuum inner cylinder (100) and the vacuum outer cylinder (200) form a first vacuum interlayer, characterized in that, The low-temperature inner cylinder (500) and the low-temperature outer cylinder (600) are disposed within the first vacuum interlayer; the first vacuum interlayer has an opening, and the first vacuum interlayer includes a cold shield structure, the cold shield structure including a cold shield inner cylinder and a cold shield outer cylinder, and the precooling method includes the following steps: Gas is introduced into the first vacuum interlayer through the opening of the first vacuum interlayer to reduce the vacuum level of the first vacuum interlayer. Refrigerant (700) is filled between the low-temperature inner cylinder (500) and the low-temperature outer cylinder (600) to reduce the temperature of the cold screen structure to the target temperature value, thereby achieving pre-cooling of the cold screen structure. After the refrigerant is filled and / or the cold shield structure is cooled, the first vacuum jacket is evacuated using the openings in the first vacuum jacket to increase the vacuum level of the first vacuum jacket.

2. The precooling method for the thermostat according to claim 1, characterized in that, The cold shield structure includes a second vacuum interlayer, which is formed between the inner cylinder and the outer cylinder of the cold shield. The second vacuum interlayer includes a refrigeration component, which includes the low-temperature inner cylinder and the low-temperature outer cylinder. First, refrigerant is filled into the refrigeration component, and then the vacuum level of the first vacuum interlayer is reduced, thereby using the refrigeration component to lower the temperature of the cold screen structure; or, the vacuum level of the first vacuum interlayer is reduced first, and then refrigerant is filled into the refrigeration component, thereby using the refrigeration component to lower the temperature of the cold screen structure.

3. The precooling method for the thermostat according to claim 1, characterized in that, The reduction of the vacuum level of the first vacuum interlayer includes: Reduce the vacuum level of the first vacuum interlayer to the target vacuum value.

4. The precooling method for the thermostat according to claim 3, characterized in that, The target vacuum value is 5x10. -4 KPa to 3x10 -2 Between kPa.

5. The precooling method for the thermostat according to claim 3, characterized in that, Different temperatures of the cold shield structure correspond to different target vacuum values.

6. The precooling method for the thermostat according to any one of claims 1-5, characterized in that, A magnet structure is provided in the first vacuum interlayer of the Dewar flask.

7. The precooling method for the thermostat according to any one of claims 1-5, characterized in that, The refrigerant is liquid helium or helium gas.

8. A pre-cooling method for a superconducting magnet, characterized in that, The precooling method of the thermostat included in any one of claims 1-7.

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