Thermal Switch and Dilution Refrigerator

Abstract

The present invention provides a thermal switch and a dilution refrigerator, relating to the technical field of dilution refrigeration. The thermal switch includes a tube body and two heat conducting members. The two heat conducting members are respectively sealed at both ends of the tube body to define a sealed cavity. The two heat conducting members respond to the filling of a heat conducting gas in the sealed cavity to form heat conduction, and respond to the vacuum state in the sealed cavity to form heat isolation. Each heat conducting member is formed with a plurality of extension tubes extending towards the other heat conducting member. The extension tubes belonging to the same heat conducting member are concentrically arranged in sequence. The extension tubes belonging to different heat conducting members are alternately sleeved in the radial direction and at least partially overlap in the axial direction, and a plurality of annular gaps for the flow of the heat conducting gas are formed between adjacent extension tubes.

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 capable of achieving extremely low temperatures (millikelvin level, mK), and is widely used in fields such as quantum computing, condensed matter physics research, astronomical detection, and materials science. In quantum computing, a dilution refrigerator provides a cryogenic environment close to absolute zero for superconducting qubits 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, a dilution refrigerator is also used in deep space detectors to cool infrared sensors to improve detection sensitivity. With the rapid development of quantum technology and cryophysics, the dilution refrigerator has become an indispensable core device in scientific research and high-tech fields.

[0003] The dilution refrigerator achieves refrigeration based on the phase transition characteristics of a mixture of helium-3 ( 3 He) and helium-4 ( 4 He). Its core principle is to utilize the endothermic process of 3 He separating from the 3 He- 4 He mixture at extremely low temperatures. Specifically, when 3 He atoms pass through the phase boundary from the concentrated phase ( 3 He-rich phase) into the dilute phase ( 4 He-depleted phase), heat is absorbed, thereby reducing the system temperature. This process is achieved through continuous cycling: 3 The He gas is compressed, cooled and reinjected into the mixture to form a continuous refrigeration effect. Dilution refrigerators are usually used in combination 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] A thermal switch is a key component in a dilution refrigerator, which is used to control the on / off of heat conduction between different temperature regions. For example, during the startup phase of the refrigerator, the thermal switch can be closed to accelerate the precooling process; after reaching the target low temperature, the thermal switch can be opened 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 related technologies, the thermal switch based on gas adsorption has a relatively simple structure and low manufacturing cost, so it is widely used. However, it has the defect of a relatively small heat exchange area, which affects the heat exchange efficiency. Therefore, how to improve the heat conduction ability of the thermal switch has become an urgent technical problem to be solved. 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 improve the heat conduction ability.

[0006] To achieve the above object, the present invention provides a thermal switch, including a tube body; two heat conducting members respectively covering both ends of the above tube body to define a sealed cavity, and the two above heat conducting members form heat conduction in response to filling a heat conducting gas in the above sealed cavity, and form heat isolation in response to the above sealed cavity being in a vacuum state; each of the above heat conducting members is formed with a plurality of extension tubes extending towards the other above heat conducting member, and the extension tubes belonging to the same heat conducting member are concentrically arranged in sequence; the extension tubes belonging to different heat conducting members are sequentially sleeved alternately in the radial direction, and at least partially overlap in the axial direction, and a plurality of annular gaps for the above heat conducting gas to flow are formed between adjacent above extension tubes.

[0007] According to an embodiment of the present invention, it further includes a control component, which is configured to adsorb the heat conducting gas in the above sealed cavity or release the heat conducting gas into the above sealed cavity in response to temperature change.

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

[0009] According to an embodiment of the present invention, the above housing is configured to be disc-shaped, and a recess is formed at the center of the upper surface of the above housing, which is suitable for installing a heat source.

[0010] According to an embodiment of the present invention, the above control component further includes a mounting seat, which is configured to support the above housing.

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

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

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

[0014] According to an embodiment of the present invention, an extension column is further formed at the center of the second heat conducting member of the two above heat conducting members, and the above extension column extends along the axial direction to define an annular gap with the inner wall of the extension tube with the smallest inner diameter in the above first heat conducting member.

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

[0016] For the thermal switch provided by the present invention, heat conduction is formed between two heat conducting members by filling a heat conducting gas into the sealed cavity, and heat insulation is formed between two heat conducting members by evacuating the sealed cavity. A plurality of concentric extension tubes with gradually increasing inner diameters are formed on each heat conducting member, and the two heat conducting members are inserted and matched through the extension tubes. A narrow annular gap is defined between adjacent extension tubes. Compared with the traditional air-gap type thermal switch, the heat exchange area is increased by several times, effectively improving the heat exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] Figure 2 is a sectional view of the thermal switch provided by the embodiment of the present invention after removing the tube body;

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

[0020] Figure 4 is Figure 3 a partial enlarged view at A in

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

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

[0023] 1, heat conducting member;

[0024] 11, extension tube;

[0025] 12, first heat conducting member;

[0026] 121, end cap;

[0027] 1211, accommodating groove;

[0028] 13, second heat conducting member;

[0029] 131, extension post;

[0030] 2, tube body;

[0031] 21, sealed cavity;

[0032] 3, control assembly;

[0033] 31. Housing;

[0034] 32. Adsorbing member;

[0035] 33. Mounting base;

[0036] 4. Cold plate;

[0037] 5. Thermal switch. Detailed implementation manners

[0038] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In the following detailed description, for the sake of explanation, many specific details are set forth to provide a thorough understanding of the embodiments of the present invention. However, obviously, one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of the present invention.

[0039] The terms used herein are merely for describing specific embodiments and are not intended to limit the present invention. The terms "including", "comprising" and the like used herein indicate the presence of the described features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0040] All terms used herein (including technical and scientific terms) 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] In the case of using expressions such as "at least one of A, B, and C", generally, it should be interpreted according to the meaning 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 only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0042] Figure 1 is a half-sectional perspective view of the thermal switch provided by the embodiment of the present invention, Figure 2 is a sectional view of the thermal switch provided by the embodiment of the present invention after removing the tube body, Figure 3 is a sectional view of the thermal switch provided by the embodiment of the present invention, showing the control assembly, Figure 4 is Figure 3 a partial enlarged view of the portion A in

[0043] Exemplary embodiments of the present invention provide a thermal switch, such as Figures 1 to 4 shown, comprising two heat conducting members 1 and a tube body 2. The two heat conducting members 1 are respectively capped at both ends of the tube body 2 to define a sealed cavity 21 (see Figure 4 shown). The two heat conducting members 1 respond to the filling of a heat conducting gas in the sealed cavity 21 to form heat conduction, and respond to the vacuum state in the sealed cavity 21 to form thermal isolation. Each heat conducting member 1 is formed with a plurality of extension tubes 11 extending towards the other heat conducting member 1. 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 the radial direction in sequence, 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 members 1 and the tube body 2 define the sealed cavity 21. The two heat conducting members 1 do not contact each other. By filling the sealed cavity 21 with a heat conducting gas, heat conduction is formed between the two heat conducting members 1, and by evacuating the sealed cavity 21, thermal isolation is formed between the two heat conducting members 1. Specifically, each heat conducting member 1 is formed with a plurality of concentric extension tubes 11 with gradually increasing inner diameters. The two heat conducting members 1 are inserted and matched through the extension tubes 11. In other words, the extension tubes 11 of one heat conducting member 1 are located in the intervals between the adjacent extension tubes 11 of the other heat conducting member 1. The annular gaps thus formed enable the heat conducting gas to fully exchange heat with the two heat conducting members 1 during the flow process, effectively increasing the heat exchange area and improving the heat exchange efficiency.

[0045] Exemplarily, the two heat conducting members 1 are respectively in contact with two target objects. There is a temperature difference between the two target objects. After filling with the heat conducting gas, the target object with a higher temperature transfers heat to the target object with a lower temperature. After the temperature difference between the two target objects is reduced or the temperatures are equal, the heat conducting gas is pumped out so that no heat exchange occurs between the two target objects.

[0046] In some alternative embodiments, the material of the two heat conducting members 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 both at room temperature (about 300K) and at extremely low temperatures (mk level, usually below 100mk), which can further improve the heat conduction ability of the thermal switch. While stainless steel has high mechanical strength, is stable, reliable and easy to process, and at the same time has a low thermal conductivity. When the two heat conducting members 1 are in a thermally isolated state, it can reduce heat leakage from the tube body 2.

[0047] In an exemplary embodiment, as Figure 3 shown, the thermal switch further comprises a control assembly 3, which is configured to adsorb 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. By adjusting the temperature of the control component 3, its sensitivity to the heat-conducting gas (such as the adsorption capacity) is changed, so as to realize the opening and closing control of the thermal switch.

[0049] According to an embodiment of the present invention, the control component 3 includes a housing 31 and an adsorbent 32. The housing 31 is communicated with the sealed cavity 21 through a gas pipeline. The adsorbent 32 is arranged in the housing 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 housing 31. To avoid the temperatures of the adsorbent 32 and the housing 31 affecting the target object or the heat-conducting member 1, the heat-conducting gas is transmitted through the gas pipeline, so that the housing 31 and the adsorbent 32 are as far away from the heat-conducting member 1 as possible, reducing the interference of thermal radiation.

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

[0052] Further according to an embodiment of the present invention, the housing 31 is configured in a disc shape, and a recess 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 housing 31 cooperates with the recess at the center, so that when there is a need for heat conduction, the heat of the heat source can quickly spread and be transferred to the adsorbent 32, so as to release the heat-conducting gas as soon 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 arranged in the recess to monitor the heating temperature.

[0055] In some other embodiments, the housing 31 can also be configured in a cube shape. Correspondingly, the heat source adopts a heating plate to facilitate heat transfer.

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

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

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

[0059] In such an embodiment, to further reduce the thermal 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 part of the heat. For example, in a dilution refrigerator, 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 assembly 3 is usually also mounted on the cold plate. Therefore, the mounting seat 33 with heat-insulating ability effectively reduces the influence on the cold plate.

[0060] Exemplarily, the heat-insulating material includes but is 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 in the vicinity of the extremely low temperature range (mk level, usually lower than 100 mk), its adsorption capacity is significantly enhanced, effectively adsorbing the heat-conducting gas, making the sealing cavity 21 as close to the vacuum state as possible, and achieving thermal isolation between the two heat-conducting members 1. When the temperature rises under the influence of the heat source, the adsorption capacity of the activated carbon decreases, releasing the heat-conducting gas into the sealing cavity 21, enabling the two heat-conducting members 1 to form heat conduction.

[0063] In an exemplary embodiment, as Figures 2 - 3 shown, the first heat-conducting member 12 of the two heat-conducting members 1 includes an end cap 121. A receiving groove 1211 is formed on the lower surface of the end cap 121. 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 in interference fit with the end cap 121.

[0064] In such an embodiment, since the extension tube 11 has a long length and a small thickness, the extension tube 11 with the smallest inner diameter is assembled to the end cap 121 by an interference fit method to reduce the processing difficulty.

[0065] Specifically, during assembly, the extension tube 11 is first cooled to make it contract, and after being inserted into the receiving groove 1211, it returns to the normal temperature (such as room temperature). In this way, the extension tube 11 and the end cap 121 can be tightly combined, and during subsequent use, the temperatures of the extension tube 11 and the end cap 121 change synchronously, without causing the failure of the interference fit.

[0066] In some other embodiments, the end faces of the remaining extension tubes 11 of the first heat-conducting member 12 abut against the lower surface of the end cap 121, and the arc-shaped outer side faces abut against the inner wall of the tube body 2, or sequentially abut against the arc-shaped inner side faces of adjacent extension tubes 11.

[0067] According to the embodiment of the present invention, as Figures 2 - 3As shown, an extension column 131 is further formed at the center of the second heat conducting member 13 in the two heat conducting members 1. The extension column 131 extends along 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 cap 121. The extension column 131 is formed at the center of the end cap 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 through.

[0069] In some other embodiments, the installation method of the extension tube 11 of the second heat conducting member 13 is similar to that of the other extension tubes 11 of the first heat conducting member 12, which will not be elaborated here.

[0070] In some other embodiments, the heat conducting gas is preferably helium. The boiling point of helium is 4.2K, which not only meets the conventional working environment but also remains gaseous in dilution refrigeration equipment. Moreover, helium has a high thermal conductivity, which is beneficial to improving the heat exchange efficiency. In addition, helium has stable chemical properties and 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 the embodiment of the present invention.

[0072] The exemplary embodiment of the present invention also provides a dilution refrigerator, which includes a plurality of cold plates 4 arranged in parallel at intervals along the axial direction and a thermal switch 5 as described in any of the above embodiments. The two heat conducting members 1 of the thermal switch 5 are respectively connected to adjacent cold plates 4 of multiple levels, so that adjacent cold plates 4 of multiple levels form heat conduction or thermal isolation.

[0073] In such an embodiment, the multiple-level cold plates 4 include 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 ends, the core cold plate continues to be cooled by the dilution refrigeration core. At this time, the thermal switch 5 is closed to prevent the heat of the pre-cooling cold plate from leaking to the core cold plate.

[0074] Those skilled in the art can understand that the features described in the various embodiments of the present invention can 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 can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present invention.

[0075] The embodiments of the present invention have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although the embodiments have been described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and all such substitutions and modifications should 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; 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.

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 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.

9. 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 8, 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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