Multi-stage regenerative dilution refrigerator system

Abstract

The application discloses a multi-stage cold accumulation type dilution refrigerator system, which comprises a gas circuit, a refrigeration part and a cold accumulation part. The gas circuit comprises an air inlet pipeline and an air extraction pipeline. The refrigeration part pre-cools working gas in the gas circuit to a target temperature interval. The refrigeration part comprises a cold head room temperature part, a first-stage cold head and a second-stage cold head. One end of the first-stage cold head is connected with the cold head room temperature part and is in thermal connection with the air inlet pipeline. The second-stage cold head is connected with the other end of the first-stage cold head. The cold accumulation part is in thermal connection with the air inlet pipeline, and the cold accumulation part maintains the working gas in the target temperature interval. The cold accumulation part comprises at least two cold accumulation assemblies. Each cold accumulation assembly comprises a cold disc and a cold accumulator. The cold accumulator is fixedly connected with the surface of the cold disc, the cold accumulator is filled with a cold accumulation material, and the cold accumulation material is a solid.

Description

Technical Field

[0001] This application relates to the field of cryogenic refrigeration technology, and more specifically, to a multi-stage cold storage dilution refrigeration system. Background Technology

[0002] Liquid helium-free dilution refrigerators currently used in the milliKelvin (mK) temperature range have become key equipment in quantum technology and fundamental physics experiments. These devices typically rely on pulse tube refrigerators as precooling sources, and their advantages include not consuming liquid helium and being easy to operate and maintain.

[0003] However, the inventors of this application discovered that the pulse tube refrigerator inevitably generates micron-level mechanical vibrations during operation. These vibrations severely limit the effectiveness of the equipment in high-precision measurements such as scanning probes and low-temperature weak signal readouts. Although these vibrations can be suppressed by designing unique vibration-damping mechanical structures, successfully reducing the vibration level to approximately 20 nanometers, this level is still insufficient for certain specialized measurement methods that require extremely high vibration tolerance.

[0004] Such devices can also employ a He-4 liquid pool cooling method, using liquid helium to cool the reflux gas after the pulse tube refrigeration unit is shut down to maintain a low temperature, thus initially achieving low-vibration operation. However, the inventors of this application have also discovered that the liquid helium cooling process itself involves boiling and vaporization, forming an unavoidable vibration source that can still introduce interference under extreme measurement conditions.

[0005] The content of the background section is merely technology known to the public and does not necessarily represent existing technology in the field. Summary of the Invention

[0006] According to one aspect of this application, a multi-stage cold storage dilution refrigeration system is provided, including a gas circuit, a refrigeration section, and a cold storage section; the gas circuit includes an inlet pipe and an extraction pipe; the refrigeration section precools the working gas in the gas circuit to a target temperature range, and includes a cold head room temperature section, a first-stage cold head, and a second-stage cold head; one end of the first-stage cold head is connected to the cold head room temperature section and is thermally connected to the inlet pipe; the second-stage cold head is connected to the other end of the first-stage cold head; the cold storage section is thermally connected to the inlet pipe, and the cold storage section maintains the working gas within the target temperature range, and the cold storage section includes at least two cold storage components; each cold storage component includes a cold plate and a cold accumulator; the cold accumulator is fixedly connected to the surface of the cold plate, and the cold accumulator is filled with a cold storage material, which is solid.

[0007] According to some embodiments of this application, the cold storage unit further includes a primary thermal switch and a secondary thermal switch; one end of the primary thermal switch is connected to a primary cold head, and the other end of the primary thermal switch is connected to a cold plate; one end of the secondary thermal switch is connected to a secondary cold head, and the other end of the secondary thermal switch is connected to another cold plate.

[0008] According to some embodiments of this application, the system further includes a room temperature flange, an external vacuum shield, and at least two first shields; the external vacuum shield is connected to the lower surface of the room temperature flange and forms a first accommodating cavity to accommodate the cold storage component, the primary cold head, the secondary cold head, and the gas circuit; each first shield is connected to the lower surface of its corresponding cold plate, and each first shield is arranged around the corresponding cold storage unit.

[0009] According to some embodiments of this application, the cold storage section further includes at least one heat exchanger; one end of the at least one heat exchanger is thermally connected to the cold plate, and the other end of the at least one heat exchanger is thermally connected to the air intake pipe.

[0010] According to some embodiments of this application, the cold storage device is any one of a 40K-class cold storage device, a 4K-class cold storage device, a 1K-class cold storage device, and a 10mK-class cold storage device.

[0011] According to some embodiments of this application, the cold storage material of the 40K-level cold storage device has a first volumetric specific heat range in a first temperature range of 35K to 45K, and the first volumetric specific heat range is 0.6J / (cm³). 3 ·K)~1.5J / (cm 3 ·K).

[0012] According to some embodiments of this application, the cold storage material of the 4K-level cold storage device has a second volumetric specific heat range in a second temperature range of 2.5K to 5.5K, and the second volumetric specific heat range is not less than 0.2 J / (cm³). 3 ·K).

[0013] According to some embodiments of this application, the cold storage material of the 4K-level cold storage device is spherical particles, and the equivalent sphere diameter of the spherical particles is greater than 50 micrometers.

[0014] According to some embodiments of this application, the cold storage material for both the 1K-level cold storage unit and the 10mK-level cold storage unit is rhodium metal. 63 Cu is one or more of the following: copper enriched, gold-plated oxygen-free copper, and cerium-doped silicon dioxide.

[0015] According to some embodiments of this application, the system further includes an evaporation chamber and a mixing chamber: the evaporation chamber is disposed on the upper surface of the cold plate corresponding to the 1K-level cold storage; the mixing chamber is disposed on the upper surface of the cold plate corresponding to the 10mK-level cold storage. 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 This diagram shows the internal structure of a multi-stage cold storage dilution refrigeration system according to an embodiment of the present application when the refrigeration section is turned on.

[0018] Figure 2 This diagram illustrates the operation flow of a multi-stage cold storage dilution refrigeration system according to an embodiment of this application.

[0019] Figure 3 This diagram shows the internal structure of a multi-stage cold storage dilution refrigeration system according to an embodiment of this application when the refrigeration unit is turned off.

[0020] Explanation of reference numerals in the attached figures:

[0021] System 100.

[0022] Gas circuit 10; refrigeration section 20; cold storage section 30; room temperature flange 40; external vacuum shield 50; first shield 60; evaporation chamber 70; mixing chamber 80; activated carbon cold trap 90.

[0023] Air intake pipe 11; air extraction pipe 12.

[0024] 21. Temperature section of the cold head; 22. Primary cold head; 23. Secondary cold head.

[0025] Cold storage component 31; primary thermal switch 32; secondary thermal switch 33; heat exchanger 34.

[0026] 311. First-stage cold plate; 312. First-stage cold storage unit; 313. Second-stage cold plate; 314. Third-stage cold storage unit; 315. Third-stage cold storage unit; 316. Fourth-stage cold plate; 317. Fourth-stage cold storage unit; 318. Detailed Implementation

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] The English terms used in this application, their full English names, and their corresponding Chinese definitions are as follows:

[0033] PTC stands for Pulse Tube Cooler.

[0034] GHS, Gas Handle System.

[0035] MC stands for Mixing Chamber.

[0036] OVC, Outer Vaccum Chamber.

[0037] This application provides a multi-stage cold storage dilution refrigeration system 100, see [link]. Figure 1 The system 100 includes a gas circuit 10, a refrigeration unit 20, and a cold storage unit 30.

[0038] According to an example embodiment, the gas circuit 10 may include an inlet line 11 and an extraction line 12. An external gas handling system can provide working gas, and the inlet line 11 can deliver the working gas. The extraction line 12 can extract the working gas to the external gas handling system. The gas handling system may be a gas circulation system located at room temperature, including a main circulation molecular pump, a forepump, a compressor, a gas reservoir, and a cold trap.

[0039] According to an example embodiment, the refrigeration unit 20 can pre-cool the working gas in the gas circuit 10 to a target temperature range. See also Figure 1 The refrigeration unit 20 may include a cold head room temperature section 21, a primary cold head 22, and a secondary cold head 23. The target temperature range can be a preset working temperature of the working gas, and the target temperature range can be set according to temperature requirements; this application does not impose any limitations. For example, the target temperature range can be 10 mK.

[0040] One end of the primary cooling head 22 is connected to the ambient temperature section 21 of the cooling head, and the primary cooling head 22 is thermally connected to the intake pipe 11. For example, the intake pipe 11 can be wrapped around the outer wall of the primary cooling head 22. The secondary cooling head 23 is connected to the other end of the primary cooling head 22. For example, the cooling section 20 can be a pulse tube refrigerator.

[0041] According to the example embodiment, the cold storage unit 30 is thermally connected to the intake pipe 11. The cold storage unit 30 maintains the working gas within a target temperature range. The cold storage unit 30 includes at least two cold storage components 31. Each cold storage component 31 includes a cold plate and a cold accumulator.

[0042] The cold plate can be positioned near the gas circuit 10, and is thermally connected to the intake pipe 11. The accumulator can be fixedly connected to the surface of the cold plate, and the accumulator and cold plate can be thermally connected. For example, the surfaces of the accumulator and cold plate that come into contact can be gold-plated to reduce interfacial thermal resistance and increase thermal connection. The accumulator can also be fastened to the cold plate using screws or other connectors, achieving a sufficient thermal connection between the accumulator and cold plate. Applying low-temperature thermal grease to the interface between the accumulator and cold plate further facilitates thermal contact.

[0043] The cold accumulator is filled with a cold storage material, which is solid. The type of cold storage material can be selected based on the type of cold accumulator.

[0044] Optionally, the cold storage device can be any one of a 40K cold storage device, a 4K cold storage device, a 1K cold storage device, and a 10mK cold storage device.

[0045] For example, the cold storage device can be a 40K-level cold storage device, and the cold storage material filled in the 40K-level cold storage device can have a volumetric specific heat of approximately 1 J / (cm³) near the temperature range of 40K. 3 Cold storage materials with properties of K.

[0046] The refrigeration unit 20 can pre-cool the working gas in the intake pipe 11 through the primary cold head 22 and the secondary cold head 23, and store cold in the cold accumulator. When the refrigeration unit is shut down, the solid cold storage material of the cold accumulator provides a stable cold source, so that the working gas can be maintained in the target temperature range.

[0047] Through the above embodiments, the technical solution of this application can pre-cool the working gas to the target working range using a solid-state refrigeration unit, and maintain the temperature of the working gas within the target working range using a cold storage unit. This application can achieve cold storage in different temperature ranges by setting multiple cold storage components. The technical solution of this application can achieve multi-temperature zone cold storage using solid cold storage materials, providing a stable cold source after the refrigeration unit stops, thereby achieving a low-vibration, long-term operation dilution refrigeration cycle.

[0048] Optionally, see Figure 1 The cold storage unit 30 also includes a primary thermal switch 32 and a secondary thermal switch 33. One end of the primary thermal switch 32 is connected to the primary cold head 22, and the other end of the primary thermal switch 32 is connected to a cold plate. One end of the secondary thermal switch 33 is connected to the secondary cold head 23, and the other end of the secondary thermal switch 33 is connected to another cold plate.

[0049] For example, the cold storage unit may include two cold storage components, which may be a primary cold storage component and a secondary cold storage component. The primary cold storage component may include a primary cold plate 311 and a primary cold accumulator 312. The secondary cold storage component may include a secondary cold plate 313 and a secondary cold accumulator 314.

[0050] One end of the primary thermal switch 32 is connected to the primary cold head 22, and the other end of the primary thermal switch 32 is connected to the primary cold plate 311. The primary thermal switch 32 can control the thermal connection between the primary cold head 22 and the primary cold plate 311 (e.g., a 40K class cold plate).

[0051] One end of the secondary thermal switch 33 is connected to the secondary cold head 23, and the other end is connected to the secondary cold plate 312 (e.g., a 4K class cold plate). The secondary thermal switch 33 can control the thermal connection between the secondary cold head 23 and the secondary cold plate 312.

[0052] The primary thermal switch 32 and the secondary thermal switch 33 include, but are not limited to, mechanical thermal switch forms and air gap thermal switch forms.

[0053] Optionally, see Figure 1 The system 100 also includes a room temperature flange 40, an external vacuum shield 50, and at least two first shield 60s.

[0054] The external vacuum shield 50 is connected to the lower surface of the room temperature flange 40, forming a first accommodating cavity. This first accommodating cavity can accommodate the cold storage component 31, the primary cold head 22, the secondary cold head 23, and the gas circuit 10. This first accommodating cavity can be an external vacuum chamber (OVC). The external vacuum shield 50 can be connected to the room temperature flange 40 to isolate the OVC from the external atmospheric environment. The OVC can be evacuated to a vacuum state through an external pump unit and the pre-reserved evacuation port on the room temperature flange 40.

[0055] Each first shielding barrel 60 is connected to the lower surface of its corresponding cold plate, and each first shielding barrel 60 is arranged around the corresponding cold regenerator. The chambers formed by the first shielding barrel 60 and the corresponding cold plate can communicate with each other and with the OVC (Outer Vacuum Container). The first shielding barrel 60 can isolate the high-temperature part from the heat radiation of the cold plate. For example, each first shielding barrel 60 can be connected to the OVC of the outer vacuum shielding barrel 50. At least two first shielding barrels 60 can progressively isolate the high-temperature part from the low-temperature part.

[0056] The material of the first shielding barrel 60 can be one or more of gold, aluminum, and copper, preferably aluminum or gold-plated copper. For example, the first shielding barrel 60 corresponding to the 1K temperature zone cold storage can be a gold-plated copper barrel, while the first shielding barrel 60 corresponding to the 4K and 40K temperature zone cold storage can be an aluminum shielding barrel.

[0057] The technical solution of this application can shield the high-temperature part from radiative heat leakage to the cold storage material through the outer vacuum shield and the first shield.

[0058] Optionally, see Figure 1 The cold storage unit 30 also includes at least one heat exchanger 34. One end of the heat exchanger 34 is thermally connected to the cold plate, and the other end of the heat exchanger 34 is thermally connected to the inlet pipe 11. For example, by setting the heat exchanger 34 on the primary cold plate 311 and the secondary cold plate 313, the heat exchange efficiency between the inlet pipe 11 and the primary cold plate 311, and between the inlet pipe 11 and the secondary cold plate 313 can be improved, thereby achieving cooling of the circulating working gas and maintaining the dilution refrigeration cycle.

[0059] Optionally, the cold storage material of the 40K-class cold storage device has a first volumetric specific heat range in the first temperature range, which is 35K to 45K, and the first volumetric specific heat range is 0.6J / (cm³). 3 ·K)~1.5J / (cm 3 ·K). The cold storage material of a 40K-class cold storage unit may include one or more of high-purity copper, high-purity aluminum, rare earth metal erbium and its alloys.

[0060] Optionally, the cold storage material of the 4K-level cold storage device has a second volumetric specific heat range in the second temperature range, which is 2.5K to 5.5K, and the second volumetric specific heat range is not less than 0.2J / (cm³). 3 ·K). The cold storage materials for 4K-class cold storage units may include one or more of the following: silver oxide, copper oxide, rare earth gadolinium oxides Gd2O2S, GdAlO3, rare earth metal compounds Er3Ni, and holmium copper.

[0061] Optionally, the cavity of the 4K-class cold storage unit has a double-layer structure. The inner layer can be made of a thermally conductive metal material to facilitate sufficient heat exchange between the cold storage material and the cold plate. For example, the material of the inner layer includes, but is not limited to, oxygen-free copper. The outer layer can be made of a material with poor thermal conductivity to shield the cold storage material from radiative heat leakage from the high-temperature parts of the system. The material of the outer layer includes, but is not limited to, stainless steel.

[0062] Optionally, the cold storage material of the 4K-level cold storage device is spherical particles, and the equivalent sphere diameter of the spherical particles is greater than 50 micrometers.

[0063] Optionally, the cold storage material for both the 1K-class and 10mK-class cold storage units is rhodium. 63 Cu is one or more of the following: copper enriched, gold-plated oxygen-free copper, and cerium-doped silicon dioxide.

[0064] For example, see Figure 1 The cold storage unit 30 may include four cold storage components 311, which may be a primary cold storage component, a secondary cold storage component, a tertiary cold storage component, and a quaternary cold storage component, respectively. The primary cold storage component may include a primary cold plate 311 and a primary cold accumulator 312. The secondary cold storage component may include a secondary cold plate 313 and a secondary cold accumulator 314. The tertiary cold storage component may include a tertiary cold plate 315 and a tertiary cold accumulator 316. The quaternary cold storage component may include a quaternary cold plate 317 and a quaternary cold accumulator 318.

[0065] The primary cold storage unit can be a 40K-class cold storage unit. The first shielding barrel 60 corresponding to the 40K-class cold storage unit can also be a 40K-class shielding barrel. The secondary cold storage unit can be a 4K-class cold storage unit. The first shielding barrel 60 corresponding to the 4K-class cold storage unit can also be a 4K-class shielding barrel. The tertiary cold storage unit can be a 1K-class cold storage unit. The first shielding barrel 60 corresponding to the 1K-class cold storage unit can also be a 1K-class shielding barrel. The quaternary cold storage unit can be a 10mK-class cold storage unit. The first shielding barrel 60 corresponding to the 10mK-class cold storage unit can also be a 10mK-class shielding barrel. A tubular heat exchanger and a silver powder heat exchanger are installed between the 1K-class and 10mK-class cold storage units to improve the heat exchange efficiency between the intake pipe and the tertiary cold plate, and between the intake pipe and the quaternary cold plate.

[0066] Through the above embodiments, the technical solution of this application can achieve low-temperature operation in multiple temperature zones through multi-stage cold storage components. Furthermore, the multi-stage cold storage component structure has good scalability and compatibility, allowing for the modification of traditional dilution refrigeration systems into low-vibration versions with minimal modification costs. The multi-stage cold storage component structure is easy to install and replace, demonstrating significant advantages in system maintenance, material replacement, or subsequent upgrades.

[0067] The technical solution presented in this application eliminates the need for liquid helium and avoids vaporization disturbances, simplifying the operation process and improving system operational safety and long-term stability, making it suitable for unattended experimental scenarios. This technical solution provides a feasible path for constructing portable, desktop, or embedded cryogenic refrigeration platforms, and is expected to accelerate the development of lightweight and engineered cryogenic scientific equipment.

[0068] Optionally, see Figure 1 The system 100 also includes an evaporation chamber 70 and a mixing chamber 80. The evaporation chamber 70 is disposed on the upper surface of the cold plate corresponding to the 1K-level cold storage unit. The mixing chamber 80 is disposed on the upper surface of the cold plate corresponding to the 10mK-level cold storage unit.

[0069] The intake pipe 11 is located at the upper end of the evaporation chamber 70 and is coiled in the extraction pipe 12. The purpose is to use the low-temperature gas in the extraction pipe 12 to exchange heat with the high-temperature gas in the intake pipe 11, thereby reducing the temperature of the working gas in the intake pipe 11.

[0070] Optionally, see Figure 1 The system 100 also includes an activated carbon cold trap 90. The activated carbon cold trap 90 can be installed on the air inlet pipe 11. The activated carbon cold trap 90 uses activated carbon as an adsorbent to capture or purify the working gas through low-temperature adsorption. The activated carbon cold trap 90 can be thermally connected to the primary cold plate 311 via a copper braid, which is fixed to the upper surface of the primary cold plate 311 by screws.

[0071] Figure 2 A flowchart illustrating the operation of a multi-stage cold storage dilution refrigeration system according to an embodiment of this application is shown. Figure 2 The diagram shows the five main operating stages of the multi-stage cold storage dilution chiller system, from S1 to S5.

[0072] Cold storage stage S1, see Figure 1 The multi-stage cold storage dilution refrigeration system achieves the pre-cooling process through a pulse tube refrigeration unit. Figure 1The arrows in the cold storage components indicate the direction of cold energy transfer. When the pulse tube refrigerator is running, i.e., in PTCON mode, the cold energy is provided by the first-stage and second-stage cold heads and gradually transferred to the cold storage material for storage through the cold plates. After the conditions for condensation of the working gas helium (He-3 and He-4) are met, the helium condenses; the dilution refrigeration cycle begins, and the system is lowered to the lowest temperature. The temperature of each stage of the cold storage unit tends to be consistent with that of each stage of the cold plates, and the cold storage stage ends.

[0073] Work phase S2, see Figure 3 The pulse tube chiller is shut down, and the thermal connection between the first-stage cold head and the first-stage cold plate is disconnected through the first-stage thermal switch. The thermal connection between the second-stage cold head and the second-stage cold plate is disconnected through the second-stage thermal switch, which greatly reduces the heat leakage of the first-stage and second-stage cold heads. Figure 3 The arrows in the cold storage components indicate the direction of cold energy transfer. When the pulse tube refrigerator is off (PTC OFF), the cold energy is provided by the cold storage material to maintain the temperature of each stage of the cold plate. Heat exchangers are installed on the first and second stage cold plates to improve the heat exchange efficiency between the intake pipe and the cold plate, thereby cooling the circulating working gas, maintaining the dilution refrigeration cycle, ensuring the system's minimum temperature is below 10 mK, and preventing vibration at its source. This expands the application of liquid helium-free dilution refrigerators in vibration-sensitive fields.

[0074] In the re-storage stage S3, due to the shutdown of the pulse tube refrigerator, the cold storage capacity of the cold storage material is gradually depleted by the high-temperature working gas returning from the cooling cycle. The temperature of each stage of the cold storage unit rises significantly, and the minimum system temperature gradually rises to above 10mK. In this stage, it is necessary to close the primary thermal switch to reconnect the primary cold head and the primary cold plate, close the secondary thermal switch to reconnect the secondary cold head and the secondary cold plate, and at the same time turn on the pulse tube refrigerator to provide cooling capacity. Each stage of the cold storage unit and the corresponding cold plate then return to the minimum temperature.

[0075] The cycle stage S4 is formed by alternating between the working stage S2 and the re-cooling stage S3.

[0076] During shutdown phase S5, the system operation ends at low temperature, and the gas is collected to restore room temperature.

[0077] As one example, the multi-stage cryogenic dilution refrigerator system can be a two-stage cryogenic storage structure, suitable for high-sensitivity low-temperature measurement systems. The two cryogenic storage components can include a 4K-stage cryogenic storage component and a 10mK-stage cryogenic storage component. The 4K-stage cryogenic storage unit adopts an inner and outer double-layer structure, and the cryogenic storage material is filled with a mixture of spherical particles of Gd₂O₂S, GdAlO₃, and HoCu₂, with a particle diameter of not less than 50 micrometers. The 4K-stage cryogenic storage unit is located below the 4K-stage cold plate. A gold-plated oxygen-free copper block is placed on the 10mK-stage cold plate as the cryogenic storage material. Through this compact two-stage cryogenic storage scheme, the system can maintain an operating state below 10mK for a limited time after the pulse tube refrigerator stops.

[0078] As another embodiment, the multi-stage regenerative dilution refrigerator system can be a three-stage regenerative structure, facilitating the upgrade and application of traditional liquid helium-free dilution refrigerators. The three regenerative components can include a 40K-stage regenerative component, a 4K-stage regenerative component, and a 10mK-stage regenerative component. The regenerative material of the 40K-stage regenerative component is high-purity copper, while the regenerative material of the 4K-stage regenerative component is a mixture of spherical particles of Gd₂O₂S, GdAlO₃, and HoCu₂. The 10mK-stage regenerative component uses a gold-plated oxygen-free copper block thermally connected to the 10mK-stage cold plate in the mixing chamber. This three-stage regenerative structure can be used in cryogenic operating platforms for quantum devices with slightly lower vibration sensitivity.

[0079] As another embodiment, the multi-stage cold storage dilution refrigerator system can be a four-stage cold storage structure, suitable for scientific research platforms requiring high temperature control stability, such as scanning tunneling microscopes (STM). The four cold storage components can include a 40K-stage cold storage component, a 4K-stage cold storage component, a 1K-stage cold storage component, and a 10mK-stage cold storage component. The cold storage material for the 40K-stage cold storage unit is copper; the cold storage material for the 4K-stage cold storage unit is a mixture of spherical particles of Gd₂O₂S, GdAlO₃, and HoCu₂; and the cold storage materials for the 1K-stage and 10mK-stage cold storage units are both gold-plated oxygen-free copper blocks thermally connected to the cold plate. The four-stage cold storage structure can further extend the system's temperature maintenance time without external cooling, improving its applicability in experiments with extreme low vibration and long-term operation, such as quantum bit readout, low-temperature noise measurement, and ultra-low temperature scanning probe microscopy systems.

[0080] Through the embodiments described above under different structures and application scenarios, the multi-stage regenerative dilution refrigerator system of this application exhibits excellent flexibility and practicality. It can be applied to high-end scientific research platforms that pursue extreme low-temperature stability, as well as portable systems with strict limitations on size and cost. The multi-stage regenerative dilution refrigerator system of this application can maintain mK-level operation even after the pulse tube refrigerator is shut down, giving the system a significant advantage in vibration-sensitive measurement tasks.

[0081] 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 multi-stage cold storage dilution refrigeration system, characterized in that, include: Gas circuit, including intake pipe and exhaust pipe; The refrigeration unit, which precools the working gas in the gas circuit to the target temperature range, includes: The room temperature section of the cold head; The first-stage cold head is connected at one end to the room temperature section of the cold head and is thermally connected to the intake pipe. The secondary cold head is connected to the other end of the primary cold head; A cold storage unit, thermally connected to the intake pipe, maintains the working gas within the target temperature range. The cold storage unit includes: At least two cold storage components, each cold storage component comprising: Cold dishes; A cold storage device is fixedly connected to the surface of the cold plate, and the cold storage device is filled with a cold storage material, which is a solid.

2. The system according to claim 1, characterized in that, The cold storage unit also includes: A primary thermal switch, one end of which is connected to the primary cold head, and the other end of which is connected to a cold plate; The secondary thermal switch is connected at one end to the secondary cold head and at the other end to another cold plate.

3. The system according to claim 1, characterized in that, The system also includes: Room temperature flange; An external vacuum shield is connected to the lower surface of the room temperature flange and forms a first accommodating cavity to accommodate the cold storage component, the primary cold head, the secondary cold head, and the gas circuit. At least two first shielding barrels are provided, each first shielding barrel being connected to the lower surface of a corresponding cold plate, and each first shielding barrel being arranged around the corresponding cold accumulator.

4. The system according to claim 1, characterized in that, The cold storage unit also includes: At least one heat exchanger, one end of which is thermally connected to the cold plate and the other end of which is thermally connected to the air intake pipe.

5. The system according to claim 1, characterized in that, The cold storage device is any one of the following: a 40K cold storage device, a 4K cold storage device, a 1K cold storage device, and a 10mK cold storage device.

6. The system according to claim 5, characterized in that, The cold storage material of the 40K-level cold storage device has a first volumetric specific heat range in a first temperature range of 35K to 45K, and the first volumetric specific heat range is 0.6J / (cm³). 3 ·K)~1.5J / (cm 3 ·K).

7. The system according to claim 5, characterized in that, The cold storage material of the 4K-level cold storage device has a second volumetric specific heat range in the second temperature range, which is 2.5K to 5.5K, and the second volumetric specific heat range is not less than 0.2 J / (cm³). 3 ·K).

8. The system according to claim 5, characterized in that, The cold storage material of the 4K-level cold storage device is spherical particles, and the equivalent spherical diameter of the spherical particles is greater than 50 micrometers.

9. The system according to claim 5, characterized in that, The cold storage material for both the 1K-level cold storage device and the 10mK-level cold storage device is rhodium metal. 63 Cu is one or more of the following: copper enriched, gold-plated oxygen-free copper, and cerium-doped silicon dioxide.

10. The system according to claim 5, characterized in that, The system also includes: An evaporation chamber is located on the upper surface of the cold plate corresponding to the 1K-class cold storage unit; The mixing chamber is located on the upper surface of the cold plate corresponding to the 10mK-level cold storage unit.

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