Thermal switch and dilution refrigerator

Abstract

The invention provides a thermal switch and a dilution refrigerator, and relates to the technical field of dilution refrigeration, the thermal switch comprises a pipe body and two heat conduction members, the two heat conduction members respectively cover the two ends of the pipe body to define a sealing cavity, and the two heat conduction members respond to the sealing cavity filled with heat conduction gas to form heat conduction. And forming thermal isolation in response to a vacuum state within the sealed cavity. Each heat conduction piece is provided with a plurality of extension pipes extending towards the other heat conduction piece, the extension pipes belonging to the same heat conduction piece are concentrically and sequentially arranged, and the extension pipes belonging to different heat conduction pieces are sequentially and alternately sleeved in the radial direction and are at least partially overlapped in the axial direction; and a plurality of annular gaps for heat-conducting gas to flow are formed between the adjacent extension pipes.

Description

Technical Field

[0001] The present invention relates to the technical field of dilution refrigeration, and more specifically, to a thermal switch and a dilution refrigerator. Background Art

[0002] A dilution refrigerator is a refrigeration device that can achieve extremely low temperatures (millikelvin level, mK). It is widely used in quantum computing, condensed matter physics research, astronomical detection, and materials science. In quantum computing, a dilution refrigerator provides a low-temperature environment close to absolute zero for superconducting quantum bits to maintain quantum coherence and reduce thermal noise interference. In condensed matter physics research, a dilution refrigerator is used to explore novel quantum phenomena at low temperatures, such as superconductivity, superfluidity, and topological phase transitions. In addition, dilution refrigerators are also used in deep space probes to cool infrared sensors to improve detection sensitivity. With the rapid development of quantum technology and low-temperature physics, dilution refrigerators have become an indispensable core equipment in scientific research and high-tech fields.

[0003] Dilution refrigerators are based on helium-3 ( 3 He) and helium-4 ( 4 The core principle is to use the phase change characteristics of He mixture to achieve refrigeration. 3 He at extremely low temperatures 3 He- 4 He mixture separation endothermic process. Specifically, when 3 He atoms from the condensed phase ( 3 He-rich phase) crosses the phase boundary into the dilute phase ( 4 When the He-depleted phase is used, it absorbs heat, thereby reducing the system temperature. This process is achieved through a continuous cycle: 3 The He gas is compressed, cooled and reinjected into the mixture, creating a continuous refrigeration effect. Dilution refrigerators are usually used in conjunction with a precooling system (such as a pulse tube refrigerator or a liquid helium refrigerator) to reduce the temperature to an initial low temperature (about 1-4 K), thereby providing the basic conditions for the dilution refrigeration process.

[0004] The thermal switch is a key component in the dilution refrigerator, which is used to control the on and off of heat conduction between different temperature zones. For example, during the startup phase of the refrigerator, the thermal switch can be closed to accelerate the pre-cooling process; and after reaching the target low temperature, the thermal switch can be disconnected to reduce heat leakage. The working principle of the thermal switch is usually based on mechanisms such as gas adsorption, mechanical contact or superconducting transition. In the related technology, the thermal switch based on gas adsorption has a relatively simple structure and low manufacturing cost, so it is widely used. However, there is a defect that the heat exchange area is small, which affects the heat exchange efficiency. Therefore, how to improve the thermal conductivity of the thermal switch has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the present invention provides a thermal switch and a dilution refrigerator, which can effectively increase the internal heat exchange area and enhance the heat conduction capacity.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a thermal switch, including a tube body; two heat-conducting parts, which are respectively sealed at both ends of the above-mentioned tube body to define a sealed cavity, and the two above-mentioned heat-conducting parts form heat conduction in response to the sealing cavity being filled with heat-conducting gas, and form thermal isolation in response to the sealed cavity being in a vacuum state; each of the above-mentioned heat-conducting parts is formed with a plurality of extension tubes extending toward another of the above-mentioned heat-conducting parts, and the extension tubes belonging to the same heat-conducting part are concentrically arranged in sequence; the extension tubes belonging to different heat-conducting parts are alternately sleeved in sequence in the radial direction, and at least partially overlap in the axial direction, and a plurality of annular gaps for the above-mentioned heat-conducting gas to flow are formed between adjacent ones of the above-mentioned extension tubes.

[0007] According to an embodiment of the present invention, a control component is further included, which is configured to absorb the heat-conducting gas in the sealed cavity or release the heat-conducting gas to the sealed cavity in response to temperature changes.

[0008] According to an embodiment of the present invention, the control component includes: a shell connected to the sealed cavity through a gas pipeline; an adsorbent arranged in the shell and configured to selectively adsorb or release the heat-conducting gas.

[0009] According to an embodiment of the present invention, the housing is configured in a disc shape, and a recessed portion is formed at the center of the upper surface of the housing, which is suitable for installing a heat source.

[0010] According to an embodiment of the present invention, the control assembly further comprises a mounting base configured to support the housing.

[0011] According to an embodiment of the present invention, the mounting seat is made of a heat insulating material.

[0012] According to an embodiment of the present invention, the adsorbent includes activated carbon.

[0013] According to an embodiment of the present invention, the first heat conductive member of the two heat conductive members comprises an end cover, a receiving groove is formed on the lower surface of the end cover, and the extension tube with the smallest inner diameter of the first heat conductive member is located in the receiving groove and has an interference fit with the end cover.

[0014] According to an embodiment of the present invention, an extension column is further formed at the central portion of the second heat conductor of the two heat conductors, and the extension column extends in the axial direction to define an annular gap with the inner wall of the extension tube with the smallest inner diameter in the first heat conductor.

[0015] The present invention also provides a dilution refrigerator, comprising: a plurality of cold plates arranged in parallel and at intervals along the axial direction; a thermal switch such as that in any of the above embodiments, wherein two heat conducting members of the thermal switch are respectively connected to the cold plates of two adjacent stages, so that the cold plates of two adjacent stages form heat conduction or heat isolation.

[0016] The thermal switch provided by the present invention forms heat conduction between two heat-conducting parts by filling a heat-conducting gas into a sealed cavity, and forms thermal isolation between the two heat-conducting parts by evacuating the sealed cavity. A plurality of concentric extension tubes with gradually increasing inner diameters are formed on each heat-conducting part, and the two heat-conducting parts are plugged and matched through the extension tubes, and a narrow annular gap is defined between adjacent extension tubes. Compared with a traditional air-gap thermal switch, the heat exchange area is doubled, and the heat exchange efficiency is effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a half-section perspective view of a thermal switch provided by an embodiment of the present invention;

[0018] Figure 2 is a cross-sectional schematic diagram of a thermal switch provided by an embodiment of the present invention with the tube body removed;

[0019] Figure 3 is a schematic cross-sectional view of a thermal switch provided by an embodiment of the present invention, showing a control assembly;

[0020] Figure 4 yes Figure 3 A partial enlarged view of the middle A;

[0021] Figure 5 It is a schematic diagram of the working principle of the dilution refrigerator provided by an embodiment of the present invention.

[0022] In the drawings, the meanings of the reference numerals are as follows:

[0023] 1. Heat conducting parts;

[0024] 11. Extension pipe;

[0025] 12. A first heat conducting member;

[0026] 121, end cap;

[0027] 1211, receiving tank;

[0028] 13. A second heat conducting member;

[0029] 131. Extension column;

[0030] 2. Pipe body;

[0031] 21. Sealed cavity;

[0032] 3. Control components;

[0033] 31. Shell;

[0034] 32. Adsorption parts;

[0035] 33. Mounting seat;

[0036] 4. Cold dishes;

[0037] 5. Thermal switch. DETAILED DESCRIPTION

[0038] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0039] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0040] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0041] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0042] Figure 1 is a half-section perspective view of a thermal switch provided by an embodiment of the present invention, Figure 2 is a cross-sectional schematic diagram of the thermal switch provided by an embodiment of the present invention with the tube body removed, Figure 3 is a cross-sectional schematic diagram of a thermal switch provided by an embodiment of the present invention, showing a control component, Figure 4 yes Figure 3 A partial enlarged view of point A in the middle.

[0043] An exemplary embodiment of the present invention provides a thermal switch, such as Figures 1 to 4 As shown, it includes two heat-conducting members 1 and a tube body 2. The two heat-conducting members 1 are respectively sealed at both ends of the tube body 2 to define a sealed cavity 21 (see Figure 4 As shown in the figure, the two heat-conducting members 1 form heat conduction in response to the heat-conducting gas being filled in the sealed cavity 21, and form heat isolation in response to the sealed cavity 21 being in a vacuum state. Each heat-conducting member 1 is formed with a plurality of extension tubes 11 extending toward another heat-conducting member 1, and the extension tubes 11 belonging to the same heat-conducting member 1 are arranged concentrically in sequence, and the extension tubes 11 belonging to different heat-conducting members 1 are alternately sleeved in sequence in the radial direction, and at least partially overlap in the axial direction, and a plurality of annular gaps for the heat-conducting gas to flow are formed between adjacent extension tubes 11.

[0044] In such an embodiment, the two heat-conducting parts 1 and the tube body 2 define a sealed cavity 21, and the two heat-conducting parts 1 do not contact each other. The two heat-conducting parts 1 are heat-conducted by filling the sealed cavity 21 with heat-conducting gas, and the sealed cavity 21 is evacuated to form thermal isolation between the two heat-conducting parts 1. Specifically, a plurality of concentric extension tubes 11 with gradually increasing inner diameters are formed on each heat-conducting part 1, and the two heat-conducting parts 1 are plugged and matched through the extension tubes 11. In other words, the extension tube 11 of one heat-conducting part 1 is located in the gap between the adjacent extension tubes 11 of the other heat-conducting part 1. The annular gap formed in this way enables the heat-conducting gas to fully exchange heat with the two heat-conducting parts 1 during the flow process, effectively increasing the heat exchange area and improving the heat exchange efficiency.

[0045] Exemplarily, two heat-conducting parts 1 are respectively in contact with two targets, and there is a temperature difference between the two targets. After the heat-conducting gas is filled in, the target with higher temperature transfers heat to the target with lower temperature. After the temperature difference between the two targets is reduced or the temperatures are equal, the heat-conducting gas is extracted so that no heat exchange occurs between the two targets.

[0046] In some optional embodiments, the material of the two heat-conducting parts 1 is preferably oxygen-free copper, and the material of the tube body 2 is preferably stainless steel. Oxygen-free copper has a high thermal conductivity whether in room temperature (about 300K) or extremely low temperature (mk level, usually less than 100mk) environment, which can further improve the thermal conductivity of the thermal switch. Stainless steel has high mechanical strength, is stable and reliable, and is easy to process. At the same time, it has low thermal conductivity. When the two heat-conducting parts 1 are in a thermal isolation state, it can reduce the heat leakage from the tube body 2.

[0047] In an exemplary embodiment, Figure 3 As shown, the thermal switch further includes a control component 3 , which is configured to absorb the heat-conducting gas in the sealed cavity 21 or release the heat-conducting gas to the sealed cavity 21 in response to temperature changes.

[0048] In such an embodiment, the control component 3 is temperature sensitive, and the temperature of the control component 3 is adjusted to change its sensitivity to the heat-conducting gas (for example, adsorption capacity), thereby achieving on-off control of the thermal switch.

[0049] According to an embodiment of the present invention, the control component 3 includes a shell 31 and an adsorbent 32. The shell 31 is connected to the sealed cavity 21 through a gas pipeline. The adsorbent 32 is arranged in the shell 31 and is configured to selectively adsorb or release the heat-conducting gas.

[0050] In such an embodiment, the adsorbent 32 has different adsorption capacities for the heat-conducting gas at different temperatures, and receives external heat or dissipates heat to the outside through the shell 31. In order to prevent the temperature of the adsorbent 32 and the shell 31 from affecting the target object or the heat-conducting member 1, the heat-conducting gas is transmitted through the gas pipeline so that the shell 31 and the adsorbent 32 are as far away from the heat-conducting member 1 as possible to reduce the interference of thermal radiation.

[0051] In some preferred embodiments, the housing 31 is made of oxygen-free copper, which can transfer heat to the adsorbent 32 as quickly as possible when an external heat source is present, thereby improving the response speed of the thermal switch. The gas pipeline can be made of stainless steel to ensure pipeline strength.

[0052] Further according to an embodiment of the present invention, the housing 31 is configured in a disc shape, and a recessed portion is formed at the center of the upper surface of the housing 31, which is suitable for installing a heat source.

[0053] In such an embodiment, the disc-shaped shell 31 cooperates with the recessed portion at the center so that when heat conduction is required, the heat of the heat source can be quickly diffused and transferred to the adsorption member 32 to release the heat-conducting gas as quickly as possible and connect the two heat-conducting members 1.

[0054] Optionally, the heat source includes but is not limited to a heater, and a thermometer is also provided in the recessed portion to monitor the heating temperature.

[0055] In some other embodiments, the housing 31 may also be constructed in a cubic shape, and accordingly, a heating plate is used as the heat source to facilitate heat transfer.

[0056] In an exemplary embodiment, the control assembly 3 further includes a mounting base 33 configured to support the housing 31 .

[0057] In such an embodiment, the mounting base 33 is suitable for mounting the housing 31 on the target body. The mounting base 33 can support or suspend the housing 31, share the bearing capacity of the gas pipeline, and avoid insufficient strength of the gas pipeline and reduced service life.

[0058] According to an embodiment of the present invention, the mounting seat 33 is made of a heat insulating material.

[0059] In such an embodiment, in order to further reduce the heat radiation interference of the housing 31 and the adsorbent 32, the mounting seat 33 is made of a heat-insulating material to isolate at least a portion of the heat. For example, in a dilution refrigerator, the two heat-conducting members 1 are respectively connected to the upper cold plate and the lower cold plate (the temperature of the upper cold plate is higher than that of the lower cold plate), and for the convenience of operation, the control component 3 is usually also installed on the cold plate, so the mounting seat 33 with heat-insulating ability effectively reduces the impact on the cold plate.

[0060] Exemplary thermal insulation materials include, but are not limited to, nylon or polytetrafluoroethylene.

[0061] In an exemplary embodiment, the adsorbent 32 includes activated carbon.

[0062] In such an embodiment, when the activated carbon is close to the extremely low temperature range (mk level, usually below 100mk), the adsorption capacity of the activated carbon is significantly enhanced, and the heat-conducting gas is effectively adsorbed, so that the sealed cavity 21 is as close to the vacuum state as possible, and the thermal isolation between the two heat-conducting parts 1 is achieved. When the temperature rises under the influence of the heat source, the adsorption capacity of the activated carbon decreases, and the heat-conducting gas is released into the sealed cavity 21, so that the two heat-conducting parts 1 form heat conduction.

[0063] In an exemplary embodiment, Figure 2-Figure 3 As shown, the first heat conducting member 12 of the two heat conducting members 1 includes an end cover 121 , a receiving groove 1211 is formed on the lower surface of the end cover 121 , and the extension tube 11 with the smallest inner diameter of the first heat conducting member 12 is located in the receiving groove 1211 and is interference fit with the end cover 121 .

[0064] In such an embodiment, since the extension tube 11 is relatively long and thin, the extension tube 11 with the smallest inner diameter is assembled to the end cover 121 by interference fit to reduce the difficulty of processing.

[0065] Specifically, during assembly, the extension tube 11 is first cooled to shrink it, and then restored to normal temperature (such as room temperature) after being inserted into the receiving groove 1211, so that the extension tube 11 and the end cover 121 can be tightly combined, and in subsequent use, the temperatures of the extension tube 11 and the end cover 121 change synchronously, which will not cause the interference fit to fail.

[0066] In some other embodiments, the end surfaces of the remaining extension tubes 11 of the first heat conducting member 12 abut against the lower surface of the end cover 121 , the arcuate outer side surfaces abut against the inner wall of the tube body 2 , or abut against the arcuate inner side surfaces of adjacent extension tubes 11 in sequence.

[0067] According to an embodiment of the present invention, Figure 2-Figure 3As shown, an extension column 131 is further formed at the center of the second heat conducting member 13 of the two heat conducting members 1 . The extension column 131 extends in the axial direction to define an annular gap with the inner wall of the extension tube 11 with the smallest inner diameter in the first heat conducting member 12 .

[0068] In such an embodiment, the second heat conducting member 13 also includes an end cover 121, and an extension column 131 is formed in the central portion of the end cover 121. The extension column 131 is inserted into the extension tube 11 with the smallest inner diameter in the first heat conducting member 12. The outer wall of the extension column 131 and the inner wall of the extension tube 11 also define an annular gap for the heat conducting gas to flow.

[0069] In some other embodiments, the installation method of the extension tube 11 of the second heat-conducting member 13 is similar to the installation method of the remaining extension tubes 11 of the first heat-conducting member 12 , and will not be described in detail herein.

[0070] In some other embodiments, the heat-conducting gas is preferably helium, which has a boiling point of 4.2K, and can not only meet the conventional working environment, but also remain in a gaseous state in the dilution refrigeration equipment. Moreover, the thermal conductivity of helium is relatively high, which is conducive to improving the heat exchange efficiency. In addition, the chemical properties of helium are stable, and it does not react with common metals in the field of dilution refrigeration technology, such as oxygen-free copper, stainless steel, and aluminum.

[0071] Figure 5 It is a schematic diagram of the working principle of the dilution refrigerator provided by an embodiment of the present invention.

[0072] An exemplary embodiment of the present invention further provides a dilution refrigerator, comprising a plurality of cold plates 4 arranged in parallel and spaced apart in an axial direction and a thermal switch 5 as in any of the above embodiments. Two heat conducting members 1 of the thermal switch 5 are respectively connected to the cold plates 4 of two adjacent stages, so that the cold plates 4 of the two adjacent stages form heat conduction or heat isolation.

[0073] In such an embodiment, the multi-stage cold plate 4 includes at least one pre-cooling cold plate and at least one core cold plate. In the pre-cooling stage of the dilution refrigerator, the pre-cooling cold plate cools down the core cold plate through the thermal switch 5. After the pre-cooling stage, the core cold plate continues to cool down by the dilution refrigeration core, and the thermal switch 5 is closed at this time to prevent the heat of the pre-cooling cold plate from leaking to the core cold plate.

[0074] It will be appreciated by those skilled in the art that the features described in the various embodiments of the present invention may be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments of the present invention may be combined and / or combined in various ways. All of these combinations and / or combinations fall within the scope of the present invention.

[0075] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination advantageously. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A thermal switch, characterized in that: include: tube body; Two heat-conducting members are respectively sealed at two ends of the tube body to define a sealed cavity, and the two heat-conducting members form heat conduction in response to the sealed cavity being filled with heat-conducting gas, and form heat isolation in response to the sealed cavity being in a vacuum state; Each of the heat conducting members is formed with a plurality of extension tubes extending toward another of the heat conducting members, and the extension tubes belonging to the same heat conducting member are concentrically arranged in sequence; The extension tubes belonging to different heat-conducting parts are alternately sleeved in the radial direction and at least partially overlapped in the axial direction, and a plurality of annular gaps for the heat-conducting gas to flow are formed between adjacent extension tubes.

2. The thermal switch according to claim 1, characterized in that The invention also comprises a control component, which is configured to absorb the heat-conducting gas in the sealed cavity or release the heat-conducting gas into the sealed cavity in response to temperature changes.

3. The thermal switch according to claim 2, characterized in that: The control component comprises: A housing connected to the sealed cavity via a gas pipeline; The adsorbent is arranged in the shell and is configured to selectively adsorb or release the heat-conducting gas.

4. The thermal switch according to claim 3, characterized in that: The shell is configured in a disc shape, and a recessed portion is formed at the center of the upper surface of the shell, which is suitable for installing a heat source.

5. The thermal switch according to claim 3, characterized in that: The control assembly also includes a mounting base configured to support the housing.

6. The thermal switch according to claim 5, characterized in that The mounting seat is made of heat insulating material.

7. The thermal switch according to claim 3, characterized in that: The adsorbent includes activated carbon.

8. The thermal switch according to claim 1, characterized in that The first heat-conducting member of the two heat-conducting members comprises an end cover, a lower surface of which is formed with a receiving groove, and an extension tube with the smallest inner diameter of the first heat-conducting member is located in the receiving groove and is interference-fitted with the end cover.

9. The thermal switch according to claim 8, characterized in that An extension column is further formed at the central portion of the second heat conducting member of the two heat conducting members. The extension column extends in the axial direction to define an annular gap with the inner wall of the extension tube with the smallest inner diameter in the first heat conducting member.

10. A dilution refrigerator, characterized in that: include: Multiple stages of cold plates are arranged in parallel and at intervals along the axial direction; The thermal switch according to any one of claims 1 to 9, wherein the two heat-conducting members of the thermal switch are respectively connected to the cold plates of two adjacent stages, so that the cold plates of two adjacent stages form heat conduction or heat isolation.

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