A dilution refrigeration machine

Abstract

A dilution refrigerator relates to the field of ultra-low temperature equipment technology for quantum computing. The dilution refrigerator includes a precooling stage, a dilution refrigeration unit, a room temperature flange, a 4K cold plate, an evaporation chamber cold plate, an intermediate stage cold plate, a mixing chamber cold plate, a first air gap thermal switch group, a second air gap thermal switch group, and precooling piping. When the dilution refrigerator is in precooling operation, the precooling stage is in a cooling state, the first and second air gap thermal switch groups are in a thermally conductive state, and the precooling piping is in a working fluid circulation state, allowing the working fluid in the precooling piping to exchange heat with the 4K cold plate before flowing into the dilution refrigeration unit. This dilution refrigerator, through independent precooling piping, allows the precooling circulation to directly act on the interior of the dilution refrigeration unit, improving the cooling rate of the internal stainless steel components and pipelines, and achieving rapid precooling.

Description

Technical Field

[0001] This application relates to the field of quantum computing cryogenic equipment technology, and more specifically, to a dilution refrigerator. Background Technology

[0002] Liquid helium-free dilution refrigerators used in quantum computing and cryogenic experiments typically employ small mechanical refrigerators as the cold source. They provide cooling in the 40K and 4K temperature ranges via pulse tube or GM refrigerators, and then utilize a dilution refrigeration cycle with a helium-3 / helium-4 mixture to achieve multiple cryogenic temperature ranges such as 1K, 100mK, and 20mK. Existing dilution refrigerators generally include components such as a room-temperature flange, various cold plates, a gas-gap thermal switch, an evaporation chamber, a continuous counter-current heat exchanger, a sintering heat exchanger, a mixing chamber, and a room-temperature pump system. During startup, the mechanical refrigerator first transfers cooling energy step-by-step to the cold plates in each temperature range via the gas-gap thermal switch, gradually cooling the entire unit before establishing a dilution refrigeration cycle to achieve milliKelvin-level cooling.

[0003] However, existing technologies primarily rely on the mechanical structure of each stage of the cold plate to transfer cooling capacity to the dilution refrigeration unit, lacking an active pre-cooling channel for the dilution refrigeration unit itself. Since most components in the dilution refrigeration unit, such as the evaporator, continuous counter-current heat exchanger, mixing chamber, and connecting pipes, are made of stainless steel, which has relatively low thermal conductivity, the cooling rate of the dilution refrigeration unit is slow. Even when the cold plate reaches a temperature below 10K, the internal temperature of the dilution refrigeration unit remains high, making it difficult for the mixed gas to condense. Ultimately, this results in an excessively long pre-cooling time for the entire dilution refrigeration unit. For example, for a conventional 400μW@100mK dilution refrigeration unit, it typically requires about 24 hours to cool the cold plate, followed by another 5-10 hours for gas charging and condensation to the minimum temperature.

[0004] The content in the background section is merely technology known to the public and does not necessarily represent existing technology in this field. Summary of the Invention

[0005] This application aims to provide a dilution refrigerator to solve the technical problems of slow precooling rate and long precooling time in existing dilution refrigerator units.

[0006] According to one aspect of this application, a dilution refrigeration machine is provided, which includes a precooling stage, a dilution refrigeration unit, a room temperature flange, a 4K cold plate, an evaporation chamber cold plate, an intermediate stage cold plate, a mixing chamber cold plate, a first air gap thermal switch group, a second air gap thermal switch group, and a precooling pipeline. The precooling stage provides cooling in the 4K temperature range; the dilution refrigeration unit provides dilution refrigeration based on the precooling stage, and provides cooling in the 1K, 100mK, and 20mK temperature ranges; the room temperature flange is used to mount and suspend the cold plates of each stage, including the 4K cold plate, evaporator cold plate, intermediate stage cold plate, and mixing chamber cold plate; the 4K cold plate is thermally connected to the precooling stage to ensure it operates within the 4K temperature range; the evaporator cold plate is thermally connected to the dilution refrigeration unit to ensure it operates within the 1K temperature range; the intermediate stage cold plate is thermally connected to the dilution refrigeration unit to ensure it operates within the 100mK temperature range; the mixing chamber cold plate is thermally connected to the dilution refrigeration unit to ensure it operates within the 20mK temperature range; one end of the first air gap thermal switch assembly is thermally connected to the 4K cold plate, and the first air gap thermal switch... The other end of the first air gap thermal switch group is thermally connected to the evaporator cold plate; one end of the second air gap thermal switch group is thermally connected to the evaporator cold plate, the second air gap thermal switch is thermally connected to the intermediate stage cold plate, and the other end of the second air gap thermal switch group is thermally connected to the mixing chamber cold plate; the input end of the precooling pipeline is connected to the output end of the room temperature pump system, the precooling pipeline is thermally connected to the 4K cold plate through the 4K precooling heat exchanger, and the output end of the precooling pipeline is connected to the dilution refrigeration unit; the output end and input end of the room temperature pump system are also connected to the dilution refrigeration unit to realize the circulation of the dilution refrigeration working fluid; when the dilution refrigeration machine is in the precooling working state, the precooling stage is in the precooling cooling state, the first air gap thermal switch group and the second air gap thermal switch group are in the thermal conduction state, and the precooling pipeline is in the working fluid circulation state, so that the working fluid in the precooling pipeline exchanges heat with the 4K cold plate and then flows into the dilution refrigeration unit.

[0007] According to some embodiments of this application, the precooling stage is also used to provide cooling capacity in a 40K temperature range; the cold plates of each stage of the dilution refrigeration unit also include 40K cold plates. The 40K cold plates are thermally connected to the precooling stage so that the 40K cold plates are in a 40K temperature range; the precooling pipeline is also thermally connected to the 40K cold plates through a 40K precooling heat exchanger; when the dilution refrigeration unit is in the precooling working state, the precooling stage is in the precooling cooling state, the first air gap thermal switch group and the second air gap thermal switch group are in the thermal conduction state, and the precooling pipeline is in the working fluid circulation state so that the working fluid in the precooling pipeline sequentially exchanges heat with the 40K cold plates and the 4K cold plates before flowing into the dilution refrigeration unit.

[0008] According to some embodiments of this application, the dilution refrigeration unit includes a 40K heat exchanger, a 4K heat exchanger, a Joule-Thomson heat exchanger, an evaporation chamber, a continuous counter-current heat exchanger, a sintered metal powder heat exchanger, a mixing chamber, and cryogenic piping. The 40K heat exchanger is mounted on and thermally connected to the 40K cold plate; the 4K heat exchanger is mounted on and thermally connected to the 4K cold plate; the Joule-Thomson heat exchanger is located between the 4K cold plate and the evaporation chamber cold plate; the evaporation chamber is mounted on and thermally connected to the evaporation chamber cold plate; the continuous counter-current heat exchanger is located between the evaporation chamber cold plate and the intermediate stage cold plate; the sintered metal powder heat exchanger is located between the intermediate stage cold plate and the mixing chamber cold plate; the mixing chamber is mounted on and thermally connected to the mixing chamber cold plate; the cryogenic piping includes an inlet pipe and an exhaust pipe; wherein, the inlet pipe is sequentially connected to the 40K... The inlet side of the heat exchanger, 4K heat exchanger, Joule-Thomson heat exchanger, evaporation chamber, continuous counter-current heat exchanger, sintered metal powder heat exchanger, and mixing chamber; the exhaust pipe is sequentially connected to the exhaust side of the Joule-Thomson heat exchanger, evaporation chamber, continuous counter-current heat exchanger, sintered metal powder heat exchanger, and mixing chamber; the exhaust pipe installed between the evaporation chamber exhaust port and the room temperature flange is thermally connected to the 40K cold plate and the 4K cold plate; the input end of the inlet pipe is connected to the output end of the room temperature pump system, and the output end of the exhaust pipe is connected to the input end of the room temperature pump system; the output end of the precooling pipe is connected to the cavity of the evaporation chamber.

[0009] According to some embodiments of this application, the precooling pipeline is thermally connected to the evaporator cold plate via a 1K precooling heat exchanger, and the precooling pipeline is thermally connected to the intermediate cold plate via a 100mK precooling heat exchanger; the dilution refrigeration unit includes a 40K heat exchanger, a 4K heat exchanger, a Joule-Thomson heat exchanger, an evaporator, a continuous counter-current heat exchanger, a sintered metal powder heat exchanger, a mixing chamber, and a low-temperature pipeline. A 40K heat exchanger is installed on and thermally connected to a 40K cold plate; a 4K heat exchanger is installed on and thermally connected to a 4K cold plate; a Joule-Thomson heat exchanger is located between the 4K cold plate and the evaporation chamber cold plate; the evaporation chamber is installed on and thermally connected to the evaporation chamber cold plate; a continuous counter-current heat exchanger is located between the evaporation chamber cold plate and the intermediate stage cold plate; a sintered metal powder heat exchanger is located between the intermediate stage cold plate and the mixing chamber cold plate; the mixing chamber is installed on and thermally connected to the mixing chamber cold plate; the cryogenic piping includes an inlet pipe and an exhaust pipe; wherein, the inlet pipe is sequentially connected to the 40K... The inlet side of the heat exchanger, 4K heat exchanger, Joule-Thomson heat exchanger, evaporation chamber, continuous counter-current heat exchanger, sintered metal powder heat exchanger, and mixing chamber; the exhaust pipe is sequentially connected to the exhaust side of the Joule-Thomson heat exchanger, evaporation chamber, continuous counter-current heat exchanger, sintered metal powder heat exchanger, and mixing chamber; the exhaust pipe installed between the evaporation chamber exhaust port and the room temperature flange is thermally connected to the 40K cold plate and the 4K cold plate; the input end of the inlet pipe is connected to the output end of the room temperature pump system, and the output end of the exhaust pipe is connected to the input end of the room temperature pump system; the output end of the precooling pipe is connected to the exhaust side of the mixing chamber.

[0010] According to some embodiments of this application, the 4K precooling heat exchanger is thermally connected to the 4K cold plate by mechanical anchoring; the 40K precooling heat exchanger is thermally connected to the 40K cold plate by mechanical anchoring.

[0011] According to some embodiments of this application, the 1K precooling heat exchanger is thermally connected to the evaporator cold plate by mechanical anchoring; the 100mK precooling heat exchanger is thermally connected to the intermediate stage cold plate by mechanical anchoring.

[0012] According to some embodiments of this application, the precooling pipeline is made of stainless steel.

[0013] According to some embodiments of this application, the dilution refrigeration unit further includes a cavity sidewall and a cavity sidewall. One end of the cavity sidewall is connected to the low-temperature side of the room temperature flange, and the cavity sidewall forms the front, rear, left, and right walls; the cavity bottom plate is connected to the other side of the cavity sidewall; the room temperature flange, the cavity sidewall, and the cavity bottom plate together form a vacuum-sealed cavity.

[0014] According to some embodiments of this application, the dilution refrigeration unit further includes a 40K-level radiation shield, a 4K-level radiation shield, and a 1K-level radiation shield. The 40K-level radiation shield is connected to one side of the 40K cold plate, shielding against heat radiation from the high-temperature zone within the 40K temperature range; the 4K-level radiation shield is connected to one side of the 4K cold plate, shielding against heat radiation from the high-temperature zone within the 4K temperature range; and the 1K-level radiation shield is connected to one side of the evaporator chamber cold plate, shielding against heat radiation from the high-temperature zone within the 1K temperature range.

[0015] The technical solution of this application utilizes an independent precooling pipeline, allowing the precooling cycle to act directly on the interior of the dilution refrigeration unit, thereby shortening the cooling time of internal stainless steel components and pipelines. Simultaneously, the newly added precooling pipeline shares the room temperature pump system and working fluid with the existing dilution refrigeration cycle, achieving active precooling without the need for additional independent refrigeration equipment. This allows the working fluid to reach the condensation temperature more quickly, shortening the dilution refrigeration cycle setup time and ultimately effectively reducing the overall precooling time of the unit. This improves equipment startup efficiency and utilization efficiency in applications such as quantum computing and ultra-low temperature experiments. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of the structure of a dilution refrigeration machine according to an embodiment of this application is shown; Figure 2A schematic diagram of the structure of a dilution refrigeration machine according to an embodiment of this application is shown; Explanation of reference numerals in the attached figures: 1. Dilution refrigeration unit; 101. Precooling stage; 102. Dilution refrigeration unit; 103. Room temperature flange; 104. 4K cold plate; 105. Evaporator cold plate; 106. Intermediate stage cold plate; 107. Mixing chamber cold plate; 108. First air gap thermal switch assembly; 109. Second air gap thermal switch assembly; 110. Precooling piping; 111. 4K precooling heat exchanger; 112. 40K cold plate; 113. 40K precooling heat exchanger; 114. 1K precooling heat exchanger; 115. 100mK precooling heat exchanger; 116. First valve body; 1021. Evaporation chamber; 1022. Continuous counter-current heat exchanger; 1023. Sintered metal powder heat exchanger; 1024. Mixing chamber; 1025. Low-temperature piping; 10251, Intake pipe; 10252, Extraction pipe; 10253, Second valve body; 2. Room temperature pumping system. Detailed Implementation

[0018] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0019] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of these specific details, or other methods, components, materials, devices, etc. In these cases, well-known structures, methods, devices, implementations, materials, or operations will not be shown or described in detail.

[0020] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0021] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order.

[0022] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0023] According to one aspect of this application, a dilution refrigeration unit 1 is provided. See also... Figure 1 The dilution refrigeration unit 1 includes a precooling stage 101, a dilution refrigeration unit 102, a room temperature flange 103, a 4K cold plate 104, an evaporation chamber cold plate 105, an intermediate stage cold plate 106, a mixing chamber cold plate 107, a first air gap thermal switch group 108, a second air gap thermal switch group 109, and a precooling pipeline 110.

[0024] Precooling stage 101 is used to provide cooling in the 4K temperature range. For example, precooling stage 101 can be a pulse tube chiller, a Gifford-McMahon (GM) chiller, or a closed-loop helium liquefaction unit. For example, precooling stage 101 is a pulse tube chiller. The pulse tube chiller may include a 4K cold head. Cooling is provided in the 4K temperature range by the 4K cold head.

[0025] The dilution refrigeration unit 102 is used for dilution refrigeration based on the precooling stage 101, and provides cooling capacity in the 1K temperature range, the 100mK temperature range and the 20mK temperature range.

[0026] The room temperature flange 103 is used to mount and suspend the various stages of the cold trays. The room temperature flange 103 is a structural interface that mechanically separates and vacuum-seales the room temperature side and the low temperature side. The precooling stage 101 can pass through the room temperature flange 103, providing cooling capacity on the low temperature side of the room temperature flange 103. The various stages of the cold trays include the 4K cold tray 104, the evaporator cold tray 105, the intermediate stage cold tray 106, and the mixing chamber cold tray 107. For example, the room temperature flange 103 can suspend the various stages of the cold trays using support rods or suspension rods to maintain mechanical stability and thermal insulation between the stages of the cold trays.

[0027] The 4K cold plate 104 is thermally connected to the precooling stage 101 so that the 4K cold plate 104 is in the 4K temperature range. For example, the 4K cold plate 104 can be placed below the precooling stage 101 and thermally connected to the precooling stage 101 by using oxygen-free copper braided strip as a thermal connector.

[0028] The evaporator cooling plate 105 is thermally connected to the dilution refrigeration unit 102 so that the evaporator cooling plate 105 is in a temperature range of 1K. For example, the evaporator cooling plate 105 can be disposed on the lower surface of the dilution refrigeration unit 102 and thermally connected to the evaporator 1021 via a thermal switch (such as an air gap thermal switch or a mechanical thermal switch). Alternatively, the evaporator cooling plate 105 can be thermally connected to the evaporator 1021 by mechanical anchoring.

[0029] The intermediate cold plate 106 is thermally connected to the dilution refrigeration unit 102 so that the intermediate cold plate 106 is in a temperature range of 100mK. For example, the intermediate cold plate 106 can be disposed between the evaporation chamber 1021 and the mixing chamber 1024 of the dilution refrigeration unit 102. The intermediate cold plate 106 is thermally connected to the heat exchanger of the dilution refrigeration unit 102.

[0030] The mixing chamber cold plate 107 is thermally connected to the dilution refrigeration unit 102 to maintain a temperature range of 20 mK. For example, the mixing chamber cold plate 107 can be disposed on the lower surface of the mixing chamber 1024 of the dilution refrigeration unit 102 and thermally connected to the mixing chamber 1024 via a thermal switch (e.g., an air gap thermal switch or a mechanical thermal switch). Alternatively, the mixing chamber cold plate 107 can be thermally connected to the mixing chamber 1024 via mechanical anchoring, enabling the mixing chamber cold plate 107 to reach a temperature range of approximately 20 mK, providing a mounting platform for low-temperature loads such as quantum chips.

[0031] One end of the first air-gap thermal switch assembly 108 is thermally connected to the 4K cold plate 104, and the other end is thermally connected to the evaporator chamber cold plate 105. For example, the first air-gap thermal switch assembly 108 may include multiple air-gap thermal switches. The air-gap thermal switches can be those that alter thermal conductivity by charging or discharging working gas. When the air-gap thermal switch is in a thermally conductive state, the internal working gas forms a thermally conductive channel, establishing a high thermal conductivity between adjacent cold plates and achieving rapid heat transfer. When the air-gap thermal switch is in a thermally closed state, a vacuum gap is formed internally, significantly reducing thermal conductivity and thus minimizing heat leakage between different temperature zones.

[0032] The first air gap thermal switch group 108 connects the 4K cold plate 104 and the evaporator cold plate 105, enabling the cooling capacity during the pre-cooling stage to be quickly transferred from the 4K cold plate 104 to the evaporator cold plate 105.

[0033] One end of the second air gap thermal switch assembly 109 is thermally connected to the evaporator chamber cold plate 105, the second air gap thermal switch assembly 109 is thermally connected to the intermediate stage cold plate 106, and the other end of the second air gap thermal switch is thermally connected to the mixing chamber cold plate 107.

[0034] For example, the second air gap thermal switch group 109 may include multiple air gap thermal switches. This allows the cooling capacity during the pre-cooling stage to be rapidly transferred from the evaporator chamber cold plate 105 to the intermediate stage cold plate 106 and the mixing chamber cold plate 107.

[0035] The input end of the precooling pipe 110 is connected to the output end of the room temperature pump system 2. The precooling pipe 110 is thermally connected to the 4K cold plate 104 through the 4K precooling heat exchanger 111. The output end of the precooling pipe 110 is connected to the dilution refrigeration unit 102.

[0036] The room-temperature pumping system 2 is a gas circulation system comprising a main circulation molecular pump, a forepump, a compressor, a gas reservoir, and a cold trap, all located at room temperature. The room-temperature pumping system 2 can be used for the storage, filtration, and control of the working fluid in the pre-cooling pipeline 110. The working fluid can be a mixture of helium-3 and helium-4, with helium-3 as the primary component.

[0037] The inlet of the precooling pipe 110 is connected to the outlet of the room temperature pump system 2, passes sequentially through the 4K precooling heat exchanger 111 mounted on the 4K cold plate 104, and finally enters the dilution refrigeration unit 102. The 4K precooling heat exchanger 111 can be a copper heat exchanger, which is fixed to the precooling pipe 110 by silver soldering and establishes good thermal contact with the 4K cold plate 104, so that the working fluid flowing through the pipe can fully absorb the cooling capacity of the 4K cold plate 104.

[0038] The output and input ends of the room temperature pump system 2 are also connected to the dilution refrigeration unit 102 to realize the circulation of the dilution refrigeration working fluid.

[0039] The room temperature pump system 2 is not only connected to the dilution refrigeration unit 102 in a circulating manner, but also connected to the pre-cooling pipeline 110. This configuration allows the working fluid in the pre-cooling pipeline 110 to flow into the dilution refrigeration unit 102, pass through the extraction side of the dilution refrigeration unit 102, and then flow into the room temperature pump system 2.

[0040] The precooling pipeline 110 and the dilution refrigeration unit 102 can share the same set of mixed working fluid and gas control system, so that the precooling cycle and the dilution refrigeration cycle can share the same equipment, avoiding the need to add an independent circulation system, thereby reducing the complexity of the equipment and manufacturing costs.

[0041] When the dilution refrigeration unit 1 is in the pre-cooling working state, the pre-cooling stage 101 is in the pre-cooling and cooling state, the first air gap thermal switch group 108 and the second air gap thermal switch group 109 are in the thermal conduction state, and the pre-cooling pipeline 110 is in the working fluid circulation state, so that the working fluid in the pre-cooling pipeline 110 exchanges heat with the 4K cold plate 104 and then flows into the dilution refrigeration unit 102.

[0042] For example, when the dilution refrigeration unit 1 is in pre-cooling operation, the pre-cooling pipeline 110 is first evacuated. Then, the pre-cooling stage 101 is started, gradually cooling down to provide a certain amount of cooling capacity within the 4K temperature range. Simultaneously, the first air gap thermal switch group 108 and the second air gap thermal switch group 109 are controlled to enter the thermal conduction state, establishing a high thermal conductivity path between the cooling plates at each stage. Subsequently, the room temperature pump system 2 is activated, allowing the working fluid to circulate in the pre-cooling pipeline 110. The working fluid enters the dilution refrigeration unit 102, actively cooling the components inside (e.g., the evaporation chamber 1021, the mixing chamber 1024, and related connecting pipelines). This cooling method, based on the traditional method relying solely on fixed heat conduction, adds convective heat transfer of the working fluid, significantly improving the overall cooling rate of the dilution refrigeration unit 102, allowing the working fluid to reach condensation conditions earlier and quickly establishing the subsequent dilution refrigeration cycle.

[0043] When the dilution refrigeration unit 1 has completed the precooling operation and entered the dilution refrigeration operation state, the first air gap thermal switch group 108 and the second air gap thermal switch group 109 are in the thermally closed state, the precooling pipeline 110 is in the working fluid non-circulation state, and the dilution refrigeration unit 102 is in the dilution refrigeration state.

[0044] Through the above embodiments, the technical solution of this application, by using an independent precooling pipeline, allows the precooling cycle to act directly on the inside of the dilution refrigeration unit, which can shorten the cooling time of the internal stainless steel components and pipelines. Simultaneously, the newly added precooling pipeline shares the room temperature pump system and working fluid with the original dilution refrigeration cycle, achieving active precooling without the need for additional independent refrigeration equipment. This allows the working fluid to reach the condensation temperature more quickly, shortening the dilution refrigeration cycle setup time, and ultimately effectively reducing the overall precooling time, improving equipment startup efficiency and utilization efficiency in application scenarios such as quantum computing and ultra-low temperature experiments.

[0045] Optionally, the precooling stage 101 is also used to provide cooling in a 40K temperature range. For example, the pulse tube cooler may also include a 40K cold head. The 40K cold head provides cooling in a 40K temperature range. A 40K cold plate 112 may be located below the precooling stage 101 and is thermally connected to the precooling stage 101 via an oxygen-free copper braided strip as a thermal connector. A 4K cold plate 104 may be located below the 40K cold plate 112.

[0046] See Figure 1 The dilution chiller 1 also includes a 40K cold plate 112 in each stage of the cold plate system. The 40K cold plate 112 is thermally connected to the precooling stage 101 so that the 40K cold plate 112 is in the 40K temperature range. The precooling pipeline 110 is also thermally connected to the 40K cold plate 112 through a 40K precooling heat exchanger 113.

[0047] The input end of the precooling pipeline 110 is connected to the output end of the room temperature pump system 2, and passes sequentially through the 40K precooling heat exchanger 113 set on the 40K cold plate 112, the 4K precooling heat exchanger 111 set on the 4K cold plate 104, and finally enters the dilution refrigeration unit 102.

[0048] The 40K precooling heat exchanger 113 can be made of copper and fixed to the precooling pipeline 110 by silver soldering, and establishes good thermal contact with the 40K cold plate 112, so that the working fluid flowing through the pipeline can fully absorb the cooling capacity of the 40K cold plate 112.

[0049] When the dilution refrigeration unit 1 is in the pre-cooling working state, the pre-cooling stage 101 is in the pre-cooling and cooling state, the first air gap thermal switch group 108 and the second air gap thermal switch group 109 are in the thermal conduction state, and the pre-cooling pipeline 110 is in the working fluid circulation state, so that the working fluid in the pre-cooling pipeline 110 exchanges heat with the 40K cold plate 112 and the 4K cold plate 104 in sequence before flowing into the dilution refrigeration unit 102.

[0050] For example, when the dilution refrigeration unit 1 is in pre-cooling operation, the pre-cooling pipeline 110 is first evacuated. Then, the pre-cooling stage 101 is started, gradually cooling down to provide a certain amount of cooling capacity in the 40K and 4K temperature ranges. Simultaneously, the first air gap thermal switch group 108 and the second air gap thermal switch group 109 are controlled to enter the thermal conduction state, establishing a high thermal conductivity path between the cold plates at each stage. Subsequently, the room temperature pump system 2 is turned on, allowing the working fluid to circulate in the pre-cooling pipeline 110. The working fluid enters the dilution refrigeration unit 102, actively cooling the components inside (e.g., the evaporation chamber 1021, the mixing chamber 1024, and related connecting pipelines), enabling the entire dilution refrigeration unit 102 to quickly approach the working fluid condensation temperature, creating conditions for establishing the subsequent dilution refrigeration cycle.

[0051] Optionally, see Figure 1 The dilution refrigeration unit 102 includes a 40K heat exchanger ( Figure 1 (not shown in the image), 4K heat exchanger ( Figure 1 (not shown in the image), Joule-Thomson heat exchanger ( Figure 1 (Not shown in the image) Evaporation chamber 1021, continuous countercurrent heat exchanger 1022, sintered metal powder heat exchanger 1023, mixing chamber 1024 and low temperature pipeline 1025.

[0052] A 40K heat exchanger is installed on 40K cold plate 112, and is thermally connected to 40K cold plate 112. A 4K heat exchanger is installed on 4K cold plate 104, and is thermally connected to 4K cold plate 104. A Joule-Thomson heat exchanger is located between 4K cold plate 104 and evaporation chamber cold plate 105. Evaporation chamber 1021 is installed on evaporation chamber cold plate 105, and is thermally connected to evaporation chamber cold plate 105. A continuous counter-current heat exchanger 1022 is located between evaporation chamber cold plate 105 and intermediate stage cold plate 106. A sintered metal powder heat exchanger 1023 is located between intermediate stage cold plate 106 and mixing chamber cold plate 107. A mixing chamber 1024 is installed on mixing chamber cold plate 107, and is thermally connected to mixing chamber cold plate 107.

[0053] The low-temperature piping 1025 includes an inlet piping 10251 and an exhaust piping 10252. The inlet piping 10251 is sequentially connected to the inlet side of a 40K heat exchanger, a 4K heat exchanger, a Joule-Thomson heat exchanger, an evaporation chamber 1021, a continuous counter-current heat exchanger 1022, a sintered metal powder heat exchanger 1023, and a mixing chamber 1024. The exhaust piping 10252 is sequentially connected to the exhaust side of the Joule-Thomson heat exchanger, the evaporation chamber 1021, the continuous counter-current heat exchanger 1022, the sintered metal powder heat exchanger 1023, and the mixing chamber 1024.

[0054] The suction line 10252, installed between the evaporation chamber 1021 exhaust port and the room temperature flange 103, is thermally connected to the 40K cold plate 112 and the 4K cold plate 104. The input end of the intake line 10251 is connected to the output end of the room temperature pump system 2, and the output end of the suction line 10252 is connected to the input end of the room temperature pump system 2.

[0055] The output end of the precooling pipe 110 is connected to the cavity of the evaporation chamber 1021. A first valve body 116 can be installed at the input end of the precooling pipe 110. The first valve body 116 is used to control the opening and closing of the precooling pipe 110.

[0056] For example, a 40K heat exchanger allows for sufficient heat exchange between the inlet pipe 10251 and the 40K cold plate 112, enabling the 40K cold plate 112 to effectively pre-cool the working gas flowing through the inlet pipe 10251, reducing the temperature of the working gas from room temperature to approximately 40K. A 4K heat exchanger allows for sufficient heat exchange between the inlet pipe 10251 and the 4K cold plate 104, enabling the 4K cold plate 104 to effectively pre-cool the working gas flowing through the inlet pipe 10251, further reducing the temperature of the working gas to approximately 4K. The type of 40K heat exchanger can be selected according to requirements.

[0057] The Joule-Thomson heat exchanger can be placed between the 4K cold plate 104 and the port of the evaporation chamber 1021 to thermally connect the inlet pipe 10251 and the evaporation chamber 1021, so that the working gas in the inlet pipe 10251 can be fully liquefied into the working liquid.

[0058] A continuous counter-current heat exchanger 1022 is disposed between the evaporator cold plate 105 and the intermediate cold plate 106, and thermally connects the inlet pipe 10251 and the exhaust pipe 10252 between the evaporator cold plate 105 and the intermediate cold plate 106. This arrangement allows the continuous counter-current heat exchanger 1022 to ensure sufficient heat exchange between the inlet pipe 10251 and the exhaust pipe 10252 between the evaporator cold plate 105 and the intermediate cold plate 106, thereby cooling the working fluid in the inlet pipe 10251 to approximately 100 mK first.

[0059] A sintered silver powder heat exchanger is positioned between the intermediate stage cold plate 106 and the mixing chamber cold plate 107, thermally connecting the inlet pipe 10251 and the extraction pipe 10252 between them. This arrangement allows for sufficient heat exchange between the inlet pipe 10251 and the extraction pipe 10252. The working fluid (i.e., a concentrated helium-3 solution) in the inlet pipe 10251 absorbs the cooling energy from the dilute helium-3 solution flowing out of the mixing chamber 1024 and exiting the extraction pipe 10252 within the sintered silver powder heat exchanger, gradually decreasing in temperature. The concentrated helium-3 solution's enthalpy is minimized before entering the mixing chamber 1024.

[0060] The working principle of the dilution refrigeration unit 102 is as follows: A mixture of helium-3 and helium-4 gas, with helium-3 as the main component, is evaporated under reduced pressure in the evaporation chamber 1021. Driven by the room temperature pump system 2, the mixed gas flows back into the inlet pipe 10251, and liquefies after passing through a 40K heat exchanger, a 4K heat exchanger, and a Joule-Thomson heat exchanger. After passing through the evaporation chamber 1021, the continuous counter-current heat exchanger 1022, and the sintered metal powder heat exchanger 1023, it flows into the mixing chamber 1024. The concentrated helium-3 solution flowing into the mixing chamber 1024 absorbs the cooling energy of the dilute helium-3 solution flowing out of the mixing chamber 1024, and its temperature gradually decreases. Finally, at the phase separation interface in the mixing chamber 1024, the dilute phase solution continuously enters, producing a dilution refrigeration effect, which can reach a temperature on the order of 20 mK.

[0061] A second valve body 10253 can be installed at the input end of the intake pipe 10251. The second valve body 10253 is used to control the opening and closing of the intake pipe 10251.

[0062] When the dilution refrigeration unit 1 is in the pre-cooling operating state, the pre-cooling stage 101 is in the pre-cooling and cooling state, and the first air gap thermal switch group 108 and the second air gap thermal switch group 109 are in the thermal conduction state. The second valve body 10253 is in the closed state (i.e., the suction line 10252 is in the closed state). The pre-cooling line 110 is in the working fluid circulation state (i.e., the first valve body 116 is in the conducting state), so that the working fluid in the pre-cooling line 110 exchanges heat with the 4K cold plate 104 and then flows into the dilution refrigeration unit 102.

[0063] For example, when the dilution refrigerator 1 is in pre-cooling operation, the pre-cooling pipeline 110 is first evacuated. Then, the pre-cooling stage 101 is started to gradually lower the temperature, ultimately providing a certain amount of cooling capacity in the 40K and 4K temperature ranges. Simultaneously, the first air gap thermal switch group 108 and the second air gap thermal switch group 109 are controlled to enter the thermal conduction state, establishing a high thermal conductivity path between the cold plates at each stage. Subsequently, the room temperature pump system 2 is turned on, allowing the working fluid to circulate in the pre-cooling pipeline 110. The working fluid flows into the cavity of the evaporation chamber 1021. Afterward, the working fluid flows into the extraction pipeline 10252 and then into the room temperature pump system 2, completing the pre-cooling cycle.

[0064] When the dilution refrigeration unit 1 has completed the pre-cooling work and entered the dilution refrigeration working state, the first air gap thermal switch group 108 and the second air gap thermal switch group 109 are in the thermal closed state, the first valve body 116 is closed, the second valve body 10253 is open, and the dilution refrigeration unit 102 is in the dilution refrigeration state.

[0065] Through the above embodiments, the technical solution of this application connects the precooling pipeline directly to the evaporation chamber, allowing the low-temperature working fluid to enter the dilution refrigeration unit first for convective heat exchange, thus significantly accelerating the cooling speed of the entire dilution refrigeration unit.

[0066] Optionally, see Figure 2 The precooling pipe 110 is thermally connected to the evaporator cold plate 105 via a 1K precooling heat exchanger 114, and the precooling pipe 110 is thermally connected to the intermediate cold plate 106 via a 100mK precooling heat exchanger 115.

[0067] The 1K precooling heat exchanger 114 can be a copper heat exchanger, which is fixed to the precooling pipeline 110 by silver soldering and establishes good thermal contact with the evaporation chamber 1021, so that the working fluid flowing through the pipeline can fully absorb the cooling capacity of the evaporation chamber 1021.

[0068] The 100mK precooling heat exchanger 115 can be made of copper and fixed to the precooling pipeline 110 by silver soldering. It establishes good thermal contact with the intermediate cold plate 106, so that the working fluid flowing through the pipeline can fully absorb the cooling capacity of the intermediate cold plate 106.

[0069] See Figure 2 The dilution refrigeration unit 102 includes a 40K heat exchanger ( Figure 2 (not shown in the image), 4K heat exchanger ( Figure 2 (not shown in the image), Joule-Thomson heat exchanger ( Figure 2 (Not shown in the image) Evaporation chamber 1021, continuous countercurrent heat exchanger 1022, sintered metal powder heat exchanger 1023, mixing chamber 1024 and low temperature pipeline 1025.

[0070] A 40K heat exchanger is installed on and thermally connected to 40K cold plate 112. A 4K heat exchanger is installed on and thermally connected to 4K cold plate 104. A Joule-Thomson heat exchanger is located between 4K cold plate 104 and evaporator cold plate 105. Evaporator 1021 is installed on and thermally connected to evaporator cold plate 105. A continuous counter-current heat exchanger 1022 is located between evaporator cold plate 105 and intermediate stage cold plate 106. A sintered metal powder heat exchanger 1023 is located between intermediate stage cold plate 106 and mixing chamber cold plate 107. A mixing chamber 1024 is installed on and thermally connected to mixing chamber cold plate 107.

[0071] The low-temperature piping 1025 includes an inlet piping 10251 and an exhaust piping 10252. The inlet piping 10251 is sequentially connected to the inlet side of the 40K heat exchanger, the 4K heat exchanger, the Joule-Thomson heat exchanger, the evaporation chamber 1021, the continuous counter-current heat exchanger 1022, the sintered metal powder heat exchanger 1023, and the mixing chamber 1024. The exhaust piping 10252 is sequentially connected to the exhaust side of the Joule-Thomson heat exchanger, the evaporation chamber 1021, the continuous counter-current heat exchanger 1022, the sintered metal powder heat exchanger 1023, and the mixing chamber 1024. The exhaust piping 10252, installed between the exhaust port of the evaporation chamber 1021 and the room temperature flange 103, is thermally connected to the 40K cold plate 112 and the 4K cold plate 104.

[0072] The input end of the intake pipe 10251 is connected to the output end of the room temperature pump system 2, and the output end of the extraction pipe 10252 is connected to the input end of the room temperature pump system 2. The output end of the precooling pipe 110 is connected to the extraction side of the mixing chamber 1024. A first valve body 116 can be installed at the input end of the precooling pipe 110. The first valve body 116 is used to control the opening and closing of the precooling pipe 110.

[0073] A second valve body 10253 can be installed at the input end of the intake pipe 10251. The second valve body 10253 is used to control the opening and closing of the intake pipe 10251. The structure and function of each component in the dilution refrigeration unit 102 will not be described in detail.

[0074] When the dilution refrigeration unit 1 is in the pre-cooling operating state, the pre-cooling stage 101 is in the pre-cooling and cooling state, and the first air gap thermal switch group 108 and the second air gap thermal switch group 109 are in the thermal conduction state. The second valve body 10253 is in the closed state (i.e., the suction line 10252 is in the closed state). The pre-cooling line 110 is in the working fluid circulation state (i.e., the first valve body 116 is in the conducting state), so that the working fluid in the pre-cooling line 110 exchanges heat with the 4K cold plate 104 and then flows into the dilution refrigeration unit 102.

[0075] For example, when the dilution refrigeration unit 1 is in pre-cooling operation, the pre-cooling pipeline 110 is first evacuated. Then, the pre-cooling stage 101 is started, gradually cooling down to provide a certain amount of cooling capacity in the 40K and 4K temperature ranges. Simultaneously, the first air gap thermal switch group 108 and the second air gap thermal switch group 109 are controlled to enter the thermal conduction state, establishing a high thermal conductivity path between the cold plates at each stage. Subsequently, the room temperature pump system 2 is activated, allowing the working fluid to circulate in the pre-cooling pipeline 110. The working fluid flows into the mixing chamber 1024 from the evacuation side. Afterward, the working fluid flows into the evacuation pipeline 10252, passing sequentially through the sintered metal powder heat exchanger 1023, the continuous counter-current heat exchanger 1022, and the evaporation chamber 1021 before flowing into the room temperature pump system 2, completing the pre-cooling cycle. This allows the entire dilution refrigeration unit 102 to quickly approach the working fluid condensation temperature, improving pre-cooling efficiency.

[0076] When the dilution refrigeration unit 1 has completed the pre-cooling work and entered the dilution refrigeration working state, the first air gap thermal switch group 108 and the second air gap thermal switch group 109 are in the thermal closed state, the first valve body 116 is closed, the second valve body 10253 is open, and the dilution refrigeration unit 102 is in the dilution refrigeration state.

[0077] Through the above embodiments, the technical solution of this application connects the precooling pipeline directly to the exhaust side of the mixing chamber, so that the low-temperature working fluid can first enter the interior of the dilution refrigeration unit and cover the entire low-temperature reflux path, thus significantly accelerating the cooling speed of the entire dilution refrigeration unit.

[0078] Optionally, the 4K precooling heat exchanger 111 is thermally connected to the 4K cold plate 104 via mechanical anchoring. The 40K precooling heat exchanger 113 is thermally connected to the 40K cold plate 112 via mechanical anchoring. The 1K precooling heat exchanger 114 is thermally connected to the evaporator cold plate 105 via mechanical anchoring. The 100mK precooling heat exchanger 115 is thermally connected to the intermediate stage cold plate 106 via mechanical anchoring.

[0079] The technical solution of this application achieves thermal connection between the precooling heat exchanger and the corresponding cold plate through mechanical anchoring, which can establish a stable heat conduction path, facilitate installation, replacement and maintenance, and effectively avoid the thermal stress and low temperature deformation problems caused by welding, making it suitable for long-term operation in ultra-low temperature environments.

[0080] Optionally, the precooling pipe 110 is made of stainless steel. In the temperature range above 4K, the precooling pipe 110 uses a stainless steel tube with a diameter of approximately 2mm; in the temperature range below 4K, the precooling pipe 110 uses a stainless steel capillary tube with a diameter of approximately 1mm, to balance flow rate, thermal conductivity, and structural reliability. Stainless steel has a low thermal conductivity, high mechanical strength, and excellent low-temperature toughness, maintaining good structural stability even in extremely low-temperature environments.

[0081] Optionally, the dilution refrigerator 1 also includes a cavity sidewall (not shown in the figure) and a cavity base plate (not shown in the figure). One end of the cavity sidewall is connected to the low-temperature side of the room temperature flange 103, and the cavity sidewall forms the front, rear, left, and right walls. The cavity base plate is connected to the other side of the cavity sidewall. The room temperature flange 103, the cavity sidewall, and the cavity base plate together form a vacuum-sealed cavity.

[0082] For example, one end of the cavity sidewall is connected to the low-temperature side of the room temperature flange 103, and the cavity sidewalls together form the front, rear, left, and right walls. The cavity bottom plate is connected to the other side of the cavity sidewall. The cavity sidewall and cavity bottom plate of the room temperature flange 103 together form a vacuum-sealed cavity. The room temperature flange 103 can be made of stainless steel or aluminum alloy, and vacuum tightness is achieved through O-rings or metal seals. The vacuum-sealed cavity can isolate the external atmospheric environment.

[0083] Optionally, the dilution chiller 1 also includes a 40K-class radiation shield (not shown in the figure), a 4K-class radiation shield (not shown in the figure), and a 1K-class radiation shield (not shown in the figure).

[0084] The 40K-class radiation shield is connected to one side of the 40K cold plate 112, blocking heat radiation from high-temperature areas within the 40K temperature range. For example, the 40K-class radiation shield can be made of polished oxygen-free copper or aluminum alloy. The polished inner surface of the 40K-class radiation shield significantly reduces surface emissivity, thereby effectively reducing radiative heat transfer.

[0085] The 4K-grade radiation shield connects to one side of the 4K cold plate 104, blocking heat radiation from high-temperature areas within the 4K temperature range. For example, the 4K-grade radiation shield can be made of polished oxygen-free copper or aluminum alloy. The polished inner surface of the 4K-grade radiation shield significantly reduces surface emissivity, thereby effectively reducing radiative heat transfer.

[0086] A 1K-class radiation shield is connected to one side of the evaporator cold plate 105 to block heat radiation from the high-temperature zone within the 1K temperature range. For example, the 1K-class radiation shield is connected to the lower surface of the evaporator cold plate 105. The 1K-class radiation shield can be made of polished oxygen-free copper plate. The polished inner surface of the 1K-class radiation shield can significantly reduce surface emissivity, thereby effectively reducing radiative heat transfer.

[0087] Finally, it should be noted that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions of the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A dilution refrigerator, characterized by, include: Precooling stage, used to provide cooling in the 4K temperature range; A dilution refrigeration unit is used to dilute refrigeration based on the precooling stage, and provides cooling capacity in the temperature ranges of 1K, 100mK and 20mK. A room temperature flange is used to install and suspend various levels of cold trays, including 4K cold trays, evaporation chamber cold trays, intermediate stage cold trays, and mixing chamber cold trays. The 4K cold plate is thermally connected to the precooling stage so that the 4K cold plate is in the 4K temperature range; The evaporator cooling plate is thermally connected to the dilution refrigeration unit so that the evaporator cooling plate is in the 1K temperature range; The intermediate cold plate is thermally connected to the dilution refrigeration unit so that the intermediate cold plate is in the 100mK temperature range. The mixing chamber cold plate is thermally connected to the dilution refrigeration unit so that the mixing chamber cold plate is in the 20mK temperature range; The first air gap thermal switch group is thermally connected at one end to the 4K cold plate, and the other end of the first air gap thermal switch group is thermally connected to the evaporation chamber cold plate. The second air gap thermal switch group has one end thermally connected to the evaporation chamber cold plate, the second air gap thermal switch group is thermally connected to the intermediate stage cold plate, and the other end of the second air gap thermal switch is thermally connected to the mixing chamber cold plate. The precooling pipeline has its input end connected to the output end of the room temperature pump system, and its precooling pipeline is thermally connected to the 4K cold plate through a 4K precooling heat exchanger. The output end of the precooling pipeline is connected to the dilution refrigeration unit. The output and input ends of the room temperature pump system are also connected to the dilution refrigeration unit to realize the circulation of the dilution refrigerant; When the dilution refrigeration unit is in the pre-cooling working state, the pre-cooling stage is in the pre-cooling and cooling state, the first air gap thermal switch group and the second air gap thermal switch group are in the thermal conduction state, and the pre-cooling pipeline is in the working fluid circulation state, so that the working fluid in the pre-cooling pipeline exchanges heat with the 4K cold plate and then flows into the dilution refrigeration unit.

2. The dilution refrigerator of claim 1, wherein, The precooling stage is also used to provide cooling in the 40K temperature range; The various levels of cold dishes also include: A 40K cold plate is thermally connected to the precooling stage so that the 40K cold plate is within the 40K temperature range; The precooling pipeline is also thermally connected to the 40K cold plate via a 40K precooling heat exchanger. When the dilution refrigeration unit is in the pre-cooling working state, the pre-cooling stage is in the pre-cooling and cooling state, the first air gap thermal switch group and the second air gap thermal switch group are in the thermal conduction state, and the pre-cooling pipeline is in the working fluid circulation state, so that the working fluid in the pre-cooling pipeline exchanges heat with the 40K cold plate and the 4K cold plate in sequence before flowing into the dilution refrigeration unit.

3. The dilution refrigerator of claim 2, wherein, The dilution refrigeration unit includes: A 40K heat exchanger is installed on the 40K cold plate and is thermally connected to the 40K cold plate; A 4K heat exchanger is installed on the 4K cold plate and is thermally connected to the 4K cold plate; A Joule-Thomson heat exchanger is located between the 4K cold plate and the evaporator cold plate; An evaporation chamber is installed on the evaporation chamber cold plate and is thermally connected to the evaporation chamber cold plate; A continuous counter-current heat exchanger is located between the evaporator chamber cold plate and the intermediate stage cold plate; A sintered metal powder heat exchanger is located between the intermediate stage cold plate and the mixing chamber cold plate; A mixing chamber is installed on the mixing chamber cold plate and is thermally connected to the mixing chamber cold plate; Cryogenic piping, including inlet piping and exhaust piping; The air inlet pipe is sequentially connected to the air inlet side of the 40K heat exchanger, the 4K heat exchanger, the Joule-Thomson heat exchanger, the evaporation chamber, the continuous counter-current heat exchanger, the sintered metal powder heat exchanger, and the mixing chamber. The exhaust pipe is sequentially connected to the exhaust side of the Joule-Thomson heat exchanger, the evaporation chamber, the continuous counter-current heat exchanger, the sintered metal powder heat exchanger, and the mixing chamber. The evacuation pipe installed between the evaporation chamber vent and the room temperature flange is thermally connected to the 40K cold plate and the 4K cold plate. The input end of the air intake pipe is connected to the output end of the room temperature pump system, and the output end of the air extraction pipe is connected to the input end of the room temperature pump system. The output end of the precooling pipeline is connected to the cavity of the evaporation chamber.

4. The dilution refrigeration machine according to claim 2, characterized in that, The precooling pipeline is thermally connected to the evaporator cold plate via a 1K precooling heat exchanger, and the precooling pipeline is thermally connected to the intermediate cold plate via a 100mK precooling heat exchanger. The dilution refrigeration unit includes: A 40K heat exchanger is installed on the 40K cold plate and is thermally connected to the 40K cold plate; A 4K heat exchanger is installed on the 4K cold plate and is thermally connected to the 4K cold plate; A Joule-Thomson heat exchanger is located between the 4K cold plate and the evaporator cold plate; An evaporation chamber is installed on the evaporation chamber cold plate and is thermally connected to the evaporation chamber cold plate; A continuous counter-current heat exchanger is located between the evaporator chamber cold plate and the intermediate stage cold plate; A sintered metal powder heat exchanger is located between the intermediate stage cold plate and the mixing chamber cold plate; A mixing chamber is installed on the mixing chamber cold plate and is thermally connected to the mixing chamber cold plate; Cryogenic piping, including inlet piping and exhaust piping; The air inlet pipe is sequentially connected to the air inlet side of the 40K heat exchanger, the 4K heat exchanger, the Joule-Thomson heat exchanger, the evaporation chamber, the continuous counter-current heat exchanger, the sintered metal powder heat exchanger, and the mixing chamber. The exhaust pipe is sequentially connected to the exhaust side of the Joule-Thomson heat exchanger, the evaporation chamber, the continuous counter-current heat exchanger, the sintered metal powder heat exchanger, and the mixing chamber. The evacuation pipe installed between the evaporation chamber vent and the room temperature flange is thermally connected to the 40K cold plate and the 4K cold plate. The input end of the air intake pipe is connected to the output end of the room temperature pump system, and the output end of the air extraction pipe is connected to the input end of the room temperature pump system. The output end of the precooling pipeline is connected to the exhaust side of the mixing chamber.

5. The dilution refrigeration machine according to claim 2, characterized in that, The 4K precooling heat exchanger is thermally connected to the 4K cold plate by mechanical anchoring. The 40K precooling heat exchanger is thermally connected to the 40K cold plate by mechanical anchoring.

6. The dilution refrigeration machine according to claim 4, characterized in that, The 1K precooling heat exchanger is thermally connected to the evaporator cold plate by mechanical anchoring. The 100mK precooling heat exchanger is thermally connected to the intermediate stage cold plate by mechanical anchoring.

7. The dilution refrigeration machine according to claim 1, characterized in that, The precooling pipeline is made of stainless steel.

8. The dilution refrigeration machine according to claim 1, characterized in that, The dilution refrigeration unit also includes: The cavity sidewall is connected at one end to the low-temperature side of the room temperature flange, and the cavity sidewall forms the front, rear, left and right wall surfaces; The cavity bottom plate is connected to the other side of the cavity sidewall; The room temperature flange, the cavity sidewall, and the cavity bottom plate together form a vacuum-sealed cavity.

9. The dilution refrigeration machine according to claim 2, characterized in that, The dilution refrigeration unit also includes: A 40K-level radiation shield is connected to one side of the 40K cold plate to block heat radiation from high-temperature areas within the 40K temperature range. A 4K-level radiation shield is connected to one side of the 4K cold plate to block heat radiation from high-temperature areas within the 4K temperature range; A 1K-level radiation shield is connected to one side of the evaporator cold plate to block heat radiation from the high-temperature zone within the 1K temperature range.

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