Cryogenic System for Resonant Cavities and Its Testing Methods

Abstract

This invention relates to the field of resonant cavities, providing a resonant cavity cryogenic system and its testing method. The resonant cavity cryogenic system includes a vacuum chamber; a resonant cavity disposed inside the vacuum chamber; a sample holder disposed outside the resonant cavity; at least one GM refrigerator unit for providing cooling to the resonant cavity or sample holder; a mechanical vibration damping assembly configured to isolate mechanical vibrations generated during the operation of the GM refrigerator unit; and a sample rod assembly adapted to be inserted into the vacuum chamber to transport the sample to be tested to the sample holder and the resonant cavity. This resonant cavity cryogenic system can achieve microwave surface resistance measurement of sample materials in a wide temperature range of 4K-300K. Based on the GM refrigerator providing the cooling source, it reduces maintenance costs, improves the lifespan and reliability of the cryogenic system, enables low-noise, high-reliability testing of sample materials, and allows for rapid sample replacement without disrupting the cryogenic vacuum environment, thus improving testing efficiency.

Description

Technical Field

[0001] This invention relates to the field of resonant cavities, and provides a cryogenic resonant cavity system and its testing method. Background Technology

[0002] Over the past few decades, resonant cavity technology has attracted much attention due to its wide range of applications in sensing and measurement, quantum computing, and particle accelerators. In particular, in the field of sensing and measurement, resonant cavity-based microwave surface resistance characterization techniques have become a powerful tool for evaluating the potential of materials for microwave applications due to their high precision and sensitivity.

[0003] The basic principle of this technology is cavity perturbation, which involves introducing a low-loss sample into a resonant cavity and measuring the resulting changes in resonant frequency and quality factor (Q value) to inversely calculate the surface resistance of the sample.

[0004] However, existing technologies face some challenges in cryogenic testing: cryogenic conditions usually need to be maintained by liquid nitrogen, which increases the complexity of operation; and since the sensitivity of conventional copper cavities is limited, superconducting niobium cavities have been further adopted. The quality factor of such cavities is significantly improved, but they still need to be cooled by more expensive liquid helium to maintain the superconducting state, and can only be used for isothermal testing at limited temperatures, which is not convenient for real-time monitoring of sample performance changes at different temperatures. Summary of the Invention

[0005] This invention provides a resonant cavity cryogenic system to address the shortcomings of related technologies in cryogenic microwave property characterization, which relies on cryogenic liquids and can only perform constant-temperature tests.

[0006] This invention also provides a testing method for a resonant cavity cryogenic system.

[0007] A first aspect of the present invention provides a resonant cavity cryogenic system, comprising:

[0008] Vacuum enclosure;

[0009] The resonant cavity is located inside the vacuum chamber;

[0010] A sample holder is disposed outside the resonant cavity;

[0011] At least one GM refrigeration unit is used to provide cooling for the resonant cavity or the sample holder;

[0012] Mechanical vibration damping components are configured to isolate mechanical vibrations generated during the operation of the GM refrigeration unit;

[0013] A sample rod assembly adapted to be inserted into the vacuum chamber to deliver the sample to be tested to the sample holder and the resonant cavity.

[0014] According to one embodiment of the present invention, the mechanical vibration damping assembly includes a flexible bellows, one end of which is connected to the GM refrigeration unit, and the other end of which is connected to the vacuum chamber, so as to vacuum seal the vacuum chamber while isolating the mechanical vibration.

[0015] According to one embodiment of the present invention, the mechanical vibration damping assembly further includes:

[0016] Optical vibration reduction platform;

[0017] Multiple first support rods are provided, and the vacuum hood is supported on the ground by the first support rods, so that a non-contact support is formed between the vacuum hood and the optical vibration reduction platform;

[0018] The second support rod has one end connected to the GM refrigeration unit and the other end connected to a rigid connecting plate.

[0019] The third support rod has one end connected to the optical vibration damping platform and the other end connected to the rigid connecting plate to transmit the vibration of the GM refrigeration unit to the optical vibration damping platform.

[0020] According to one embodiment of the present invention, it further includes a first-stage cold screen and a second-stage cold screen, both of which are disposed within the vacuum chamber and surround the resonant cavity.

[0021] According to one embodiment of the present invention, the GM refrigeration unit includes a first GM refrigeration unit and a second GM refrigeration unit;

[0022] The first stage cold head of the first GM refrigerator and the first stage cold head of the second GM refrigerator are flexibly connected to the first stage cold screen through a flexible heat-conducting copper strip to cool the first stage cold screen, reduce vibration of the first stage cold screen, and reduce radiative heat leakage from the vacuum cover.

[0023] The second-stage cold head of the first GM refrigerator is connected to the second-stage cold screen via a flexible thermally conductive copper strip to provide cooling to the second-stage cold screen, thereby reducing vibration of the second-stage cold screen and indirectly cooling the resonant cavity while reducing radiative heat leakage from the first-stage cold screen.

[0024] The second stage cold head of the second GM refrigerator is connected to the sample holder via a flexible thermally conductive copper strip to provide cooling to the sample holder and reduce vibration of the sample holder.

[0025] According to one embodiment of the present invention, the system further includes a plurality of heat-insulating support columns, wherein the first-stage cold shield, the second-stage cold shield, and the sample holder are mounted on the vacuum hood via the heat-insulating support columns, and the first-stage cold shield, the second-stage cold shield, and the sample holder are heat-insulated from the vacuum hood via the heat-insulating support columns.

[0026] According to one embodiment of the present invention, the sample rod assembly includes a dynamic sealing structure, and a valve is provided on the vacuum shroud;

[0027] The internal space of the vacuum hood is divided into a main chamber and a transition chamber by the valve. The sample rod assembly is inserted into the transition chamber through the dynamic sealing structure. The valve is adapted to switch between an open state and a closed state. In the open state, the main chamber and the transition chamber are in communication with each other. In the closed state, the main chamber and the transition chamber are isolated from each other.

[0028] According to one embodiment of the present invention, the dynamic sealing structure includes a dynamic sealing body, a dynamic sealing ring, and a sealing nut for pressing the dynamic sealing ring;

[0029] The rod of the sample rod assembly passes through the dynamic sealing ring to form a dynamic seal.

[0030] According to one embodiment of the present invention, the sample rod assembly includes:

[0031] Hollow rod body, used to reduce thermal conductivity and heat leakage of the sample rod assembly;

[0032] A sample holder is disposed at one end of the hollow rod, and the sample holder is adapted to be detachably connected to the sample seat via a first threaded structure;

[0033] A low-temperature end connector is connected between the hollow rod and the sample holder. The low-temperature end connector and the sample holder are connected by a second thread structure. The direction of rotation of the second thread structure is opposite to that of the first thread structure, so that unidirectional rotation of the hollow rod can sequentially tighten the sample holder and the sample seat, and separate the low-temperature end connector from the sample holder.

[0034] A gemstone pillar is mounted on the sample holder so that the sample holder cools the sample holder, the gemstone pillar, and the sample on the gemstone pillar.

[0035] A second aspect of the present invention provides a testing method for a resonant cavity cryogenic system as described above, comprising:

[0036] Background testing steps: Under the condition that the sapphire column is not loaded with the sample to be tested, the main cavity of the resonant cavity low temperature system is evacuated and cooled to the preset test temperature using the GM refrigeration unit, and the first microwave response of the resonant cavity is tested.

[0037] Online sample loading steps: Close the valve to isolate the main chamber and the transition chamber, insert the sample rod assembly, independently evacuate the transition chamber to a vacuum, open the valve, use the sample rod assembly to remove the sample holder with the gemstone column from the sample holder and move it to the transition chamber, close the valve, remove the sample rod assembly from the cryogenic system, load the sample to be tested onto the gemstone column, reinsert the sample rod assembly into the transition chamber and independently evacuate the transition chamber, open the valve, and install the sample holder with the sample to be tested onto the sample holder, separate the sample holder and the cryogenic end connector of the sample rod, move it to the transition chamber, close the valve, and remove the sample rod assembly. Throughout the process, the vacuum and cryogenic environment of the main chamber are maintained.

[0038] Sample testing steps: After the temperature of the sample to be tested reaches the preset test temperature, test the second microwave response of the resonant cavity after the sample to be tested is loaded;

[0039] Characteristic calculation steps: Based on the first microwave response and the second microwave response, calculate the microwave surface resistance of the sample under test.

[0040] According to the resonant cavity cryogenic system provided in the first aspect of the present invention, the GM refrigeration unit, through its connection with the resonant cavity and sample holder for cold energy transfer, can efficiently transfer cold energy to the resonant cavity or sample holder, ensuring that the resonant cavity or sample holder receives sufficient cold energy supply, thereby maintaining the low-temperature state required for system operation and providing necessary low-temperature support for the realization of the system's core functions. The mechanical vibration damping components function to address the mechanical vibrations generated during the operation of the GM refrigeration unit, effectively isolating these vibrations through their own damping mechanism to prevent vibration transmission to the resonant cavity, sample holder, and other key components of the system. This process reduces the interference of vibration on the resonant cavity's resonant performance, ensures the stability of the sample on the sample holder, and improves the overall system's operating accuracy, ensuring the system operates in a stable environment. The vacuum chamber forms a closed space with a vacuum environment. The vacuum environment has excellent thermal insulation properties, significantly reducing the transfer of heat from the external environment to the resonant cavity inside the vacuum chamber, preventing external heat from damaging the low-temperature environment of the resonant cavity. Simultaneously, this vacuum structure effectively prevents the cold energy inside the resonant cavity from dissipating to the external environment, preventing heat leakage and ensuring that the resonant cavity can maintain a stable low-temperature state for a long time, providing a guarantee for the continuous and stable operation of the system. In addition, the sample rod assembly is designed to reduce heat exchange between the sample and the external environment during the process of inserting into the vacuum hood to transport the sample. This helps to maintain the low temperature environment of the sample holder and resonant cavity. Together with the vacuum hood and GM refrigeration unit, it achieves the effect of heat insulation and prevention of heat leakage, ensuring that the sample to be tested is still in the required low temperature state when it arrives at the detection position, thus ensuring the accuracy of the test results.

[0041] According to the test method of the resonant cavity cryogenic system provided in the second aspect of the present invention, in the background test step, the main cavity is evacuated to form a vacuum environment, which can reduce the transfer of external heat to the main cavity and prevent the internal cold energy of the main cavity from dissipating to the outside, thus preventing heat leakage. The GM refrigerator unit continuously transfers cold energy to ensure that the main cavity can stably drop to and maintain at the preset test temperature, providing the necessary low-temperature conditions for accurate testing of the first microwave response. In the sample online loading step, the main cavity and the transition cavity are isolated multiple times by valves, so that the main cavity always maintains a closed vacuum and low-temperature environment during operations such as evacuating the transition cavity, inserting and removing the sample rod assembly, and loading the sample, effectively preventing external heat from entering the main cavity, preventing the cold energy of the main cavity from leaking, and ensuring that the low-temperature state of the main cavity is not damaged. The independent evacuation operation of the transition cavity can also reduce the heat exchange when the transition cavity is connected to the main cavity, further helping to prevent heat leakage and maintain the low temperature of the main cavity. Throughout the test process, the GM refrigerator unit continuously plays the role of transferring cold energy. In the background testing step, the GM refrigerator transfers cooling energy to the main cavity, lowering it to the preset test temperature. After the sample is loaded online, the GM refrigerator continues to transfer cooling energy to the main cavity and the sample holder, sample tray, and sample under test inside, ensuring that the sample under test can quickly drop to the preset test temperature and maintain temperature stability during the sample testing step, providing the necessary low-temperature conditions for accurate testing of the second microwave response. Throughout each step of the testing method, the GM refrigerator remains operational to maintain the low-temperature environment, and the mechanical vibration damping components continuously isolate the mechanical vibrations generated by the GM refrigerator during operation. This isolation prevents vibration from being transmitted to the resonant cavity, sample holder, sample tray, and sample under test inside the main cavity, reducing vibration interference with the microwave response test of the resonant cavity, ensuring that the sample is loaded and tested in a stable environment, improving the accuracy of the first and second microwave response test data, and thus providing support for the accuracy of subsequent microwave surface resistance calculation results. The first microwave response acquired during the background testing step can eliminate the influence of the main cavity's own environment (when there is no sample under test) on the resonant cavity's microwave response, providing a background reference for subsequent sample testing. The continuous maintenance of the vacuum and low-temperature environment of the main cavity during the online sample loading step, and the stabilization of the sample temperature at the preset test temperature during the sample testing step, ensure that the second microwave response only reflects the influence of the sample under test on the resonant cavity. Based on the comparison calculation of the first and second microwave responses, background interference factors can be effectively eliminated, significantly improving the accuracy and reliability of the microwave surface resistance calculation results of the sample under test. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 This is a schematic front view of the resonant cavity cryogenic system provided by the present invention.

[0044] Figure 2 This is a schematic three-dimensional view of the resonant cavity cryogenic system provided by the present invention.

[0045] Figure 3 This is a schematic top view of the resonant cavity cryogenic system provided by the present invention.

[0046] Figure 4 yes Figure 3 A schematic cross-sectional view along the AA direction.

[0047] Figure 5 yes Figure 4 A magnified view of a portion of point A in the middle.

[0048] Figure 6 yes Figure 4 A magnified view of a section at point B in the middle.

[0049] Figure 7 This is a schematic flowchart of the testing method for the resonant cavity cryogenic system provided by the present invention.

[0050] Figure label:

[0051] 100. Vacuum shroud; 102. Resonant cavity; 104. Sample holder; 106. GM refrigerator unit; 108. Mechanical vibration damping assembly; 110. Sample rod assembly; 112. Flexible bellows; 114. Flexible thermally conductive copper strip; 116. First-stage cold shield; 118. Second-stage cold shield; 120. First-stage cold head; 122. Second-stage cold head; 124. First GM refrigerator; 126. Second GM refrigerator; 127. Thermal insulation support Column; 128, Optical vibration damping platform; 130, First support rod; 131, Second support rod; 132, Third support rod; 133, Rigid connecting plate; 134, Dynamic sealing structure; 136, Valve; 138, Main cavity; 140, Transition cavity; 142, Sealing body; 144, Dynamic sealing ring; 146, Sealing nut; 148, Hollow rod; 150, Sample holder; 152, Low temperature end connector; 154, Gemstone column. Detailed Implementation

[0052] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0053] See Figures 1 to 6 A first aspect of the present invention provides a resonant cavity cryogenic system, comprising:

[0054] Vacuum chamber 100;

[0055] The resonant cavity 102 is located inside the vacuum chamber 100;

[0056] The sample holder 104 is disposed outside the resonant cavity 102;

[0057] At least one GM cooling unit 106 is used to provide cooling for the resonant cavity 102 or the sample holder 104;

[0058] Mechanical vibration damping assembly 108 is configured to isolate mechanical vibrations generated during the operation of GM refrigeration unit 106;

[0059] The sample rod assembly 110 is adapted to be inserted into the vacuum chamber 100 to transport the sample to be tested to the sample holder 104 and the resonant cavity 102.

[0060] According to the resonant cavity cryogenic system provided in the first aspect embodiment of the present invention, the GM refrigeration unit 106, through its connection with the resonant cavity 102 and the sample holder 104 for cold energy transfer, can efficiently transfer cold energy to the resonant cavity 102 or the sample holder 104, ensuring that the resonant cavity 102 or the sample holder 104 receives sufficient cold energy supply, thereby maintaining the low temperature state required for system operation and providing necessary low temperature conditions to support the realization of the system's core functions. The mechanical vibration damping component 108 acts to address the mechanical vibrations generated during the operation of the GM refrigeration unit 106, effectively isolating these vibrations through its own damping mechanism, preventing vibration from being transmitted to the resonant cavity 102, the sample holder 104, and other key components of the system. This process can reduce the interference of vibration on the resonant performance of the resonant cavity 102, ensure the stability of the sample on the sample holder 104, and improve the overall system's operating accuracy, ensuring that the system operates in a stable environment. The enclosed space formed by the vacuum chamber 100 is a vacuum environment. This vacuum environment has excellent thermal insulation properties, significantly reducing the transfer of heat from the external environment to the resonant cavity 102 inside the vacuum chamber 100, thus preventing external heat from damaging the low-temperature environment of the resonant cavity 102. Simultaneously, this vacuum structure effectively prevents the loss of cold energy from inside the resonant cavity 102 to the external environment, preventing heat leakage and ensuring that the resonant cavity 102 can maintain a stable low temperature state for a long period, providing a guarantee for the continuous and stable operation of the system. Furthermore, during the sample transport process by inserting the sample rod assembly 110 into the vacuum chamber 100, its structural design reduces heat exchange between the sample and the external environment, further helping to maintain the low-temperature environment of the sample holder 104 and the resonant cavity 102. Together with the vacuum chamber 100 and the GM refrigeration unit 106, it achieves the effects of thermal insulation and preventing heat leakage, ensuring that the sample to be tested remains at the required low temperature state when it reaches the detection position, guaranteeing the accuracy of the detection results.

[0061] Please continue reading Figures 1 to 6 The vacuum enclosure 100 serves as the outer protective and environmental protection structure of the system, forming a closed space. Its interior is used to house the resonant cavity 102. Through its own sealing characteristics, it creates a specific working environment for the resonant cavity 102, preventing the external environment from directly affecting the resonant cavity 102.

[0062] The resonant cavity 102 is installed inside the enclosed space formed by the vacuum cover 100 and is within the enclosure of the vacuum cover 100. It is mainly used to realize the resonance process required by the system and is one of the key components for the system to complete its core functions.

[0063] Furthermore, it should be noted that in some other embodiments, since the cryogenic system can provide a wide temperature range of 4K-300K, the resonant cavity 102 used in the system is not limited to a superconducting niobium cavity, but can also be used for microwave characterization of sample materials in other temperature ranges such as liquid nitrogen temperature using a copper resonant cavity.

[0064] The sample holder 104 is located outside the resonant cavity 102 and maintains a certain positional relationship with the resonant cavity 102. Its main purpose is to place the sample to be tested and provide a stable support platform for the sample so that the sample can participate in the subsequent testing process.

[0065] The number of GM refrigeration units 106 is at least one. The GM refrigeration unit 106 establishes a cold energy transfer relationship with the resonant cavity 102 and the sample holder 104. Specifically, the cold energy transfer can be achieved through the corresponding connection structure. Its function is to provide cold energy to the resonant cavity 102 or to the sample holder 104 to meet the low temperature environment requirements of the resonant cavity 102 and the sample holder 104.

[0066] The mechanical vibration damping component 108 is configured in conjunction with the GM refrigeration unit 106. The structural design and installation method of the mechanical vibration damping component 108 are designed for the characteristics of the GM refrigeration unit 106 during operation. Its purpose is to isolate the mechanical vibration generated by the GM refrigeration unit 106 during operation and prevent the vibration from being transmitted to other components of the system through its own vibration damping mechanism.

[0067] The sample rod assembly 110 is designed to fit the opening of the vacuum chamber 100 and can be inserted into the internal space of the vacuum chamber 100. Its main function is to transport the sample to be tested from the outside of the vacuum chamber 100 to the sample holder 104 inside, and at the same time, it can also transport the sample to the resonant cavity 102, ensuring that the sample can accurately reach the position required for testing and meet the system's requirements for sample transport.

[0068] According to one embodiment of the present invention, the mechanical vibration damping assembly 108 includes a flexible bellows 112, one end of which is connected to the GM refrigeration unit 106, and the other end of which is connected to the vacuum chamber 100, so as to vacuum seal the vacuum chamber 100 while isolating mechanical vibration.

[0069] In one embodiment of the present invention, the flexible bellows 112 of the mechanical vibration damping component 108 is a corrugated tubular structure made of metal, possessing good elastic deformation capability and vacuum sealing performance. One end of the flexible bellows 112 is fixedly connected to the room temperature flange of the GM refrigeration unit 106 via a flange structure, with a sealing gasket placed between the flanges to ensure no vacuum leakage at the connection; the other end is also fixedly connected to the bottom of the vacuum cover 100 via a flange structure, with the connection method consistent with that of the GM refrigeration unit 106, forming a complete vacuum sealing channel.

[0070] The mechanical vibrations generated when the GM refrigeration unit 106 is working are first transmitted to the flexible bellows 112. The bellows absorbs the vibration energy through the elastic deformation of its own corrugated structure, preventing the vibration from being directly transmitted to the vacuum chamber 100. The length and deformation amplitude of the bellows are adapted to the vibration intensity of the GM refrigeration unit 106, ensuring sufficient vibration reduction space without affecting the relative positional stability of the vacuum chamber 100 and the refrigeration unit.

[0071] The flexible bellows 112 absorbs the vibration of the GM refrigeration unit 106 through elastic deformation, preventing the vibration from being transmitted to the vacuum chamber 100 and the internal resonant cavity 102 and sample holder 104. This reduces the interference of vibration on the microwave response test of the resonant cavity 102, ensuring accurate measurement of parameters such as the quality factor and improving the reliability of the test data. The flange sealing structure of the bellows maintains the high vacuum environment of the vacuum chamber 100, preventing external air from entering and causing heat leakage, avoiding cold loss due to the vibration damping structure, and ensuring the cooling effect.

[0072] According to one embodiment of the present invention, the mechanical vibration damping assembly 108 further includes:

[0073] Optical vibration reduction platform 128;

[0074] Multiple first support rods 130 are provided, and the vacuum hood 100 is supported on the ground by the first support rods 130, so that a non-contact support is formed between the vacuum hood 100 and the optical vibration reduction platform 128;

[0075] The second support rod 131 has one end connected to the GM refrigeration unit 106 and the other end connected to a rigid connecting plate 133.

[0076] The third support rod 132 has one end connected to the optical vibration damping platform 128 and the other end connected to the rigid connecting plate 133 to transmit the vibration of the GM refrigeration unit 106 to the optical vibration damping platform 128.

[0077] In one embodiment of the present invention, the optical vibration damping platform 128 of the mechanical vibration damping component 108 is a flat plate structure with vibration absorption function, and has a damping layer inside, which can weaken the vibration transmitted to the platform.

[0078] Multiple first support rods 130 are rigid rod-shaped structures. One end is connected to the outer peripheral wall of the vacuum chamber 100 through a fixing block, and the other end is supported on the ground. The height design of the support rods ensures that there is a preset gap between the bottom of the vacuum chamber 100 and the optical vibration reduction platform 128, forming a non-contact support and preventing the platform vibration from being transmitted to the vacuum chamber 100.

[0079] The second support rod 131 is a rigid rod, with one end fixedly connected to the outer shell of the GM refrigeration unit 106, and the other end vertically connected to the top surface of the rigid connecting plate 133. The rigid connecting plate 133 is a metal plate used to converge vibrations.

[0080] The third support rod 132 is a rigid rod, with one end vertically connected to the optical vibration damping platform 128 and the other end connected to the rigid connecting plate 133, forming a vibration transmission path between the GM refrigerator unit 106, the second support rod 131, the rigid connecting plate 133, the third support rod 132, and the optical vibration damping platform 128. The vibration generated by the GM refrigerator unit 106 is transmitted along this path to the optical vibration damping platform 128, where it is absorbed and weakened by the platform's damping layer and does not diffuse into the vacuum chamber 100.

[0081] The vibration of the GM refrigeration unit 106 is transmitted to the third support rod 132 via the second support rod 131 and the rigid connecting plate 133, and then absorbed by the damping layer of the optical vibration reduction platform 128. Compared with a single vibration reduction structure, the vibration is weakened more significantly, ensuring that the vacuum chamber 100 and its internal components are almost vibration-free, thus meeting the requirements of the resonant cavity 102 for a low-vibration environment for high-precision testing.

[0082] The first support rod 130 isolates the vacuum hood 100 from the optical vibration damping platform 128, preventing residual vibrations from the platform from being transmitted to the vacuum hood 100. This further protects the stability of the resonant cavity 102 and the sample holder 104, preventing sample position shifts or resonant frequency fluctuations caused by vibrations. At the same time, it bears the weight of the GM refrigeration unit 106 and the vacuum hood 100, keeping the support position stable and preventing tilting or loosening, thus ensuring the long-term safe operation of the system.

[0083] In addition, it should be noted that in some other embodiments, a gantry or similar structure can be used to suspend and support the vacuum cover 100 from above, so that a preset gap is maintained between the vacuum cover 100 and the optical vibration reduction platform 128, forming a non-contact support and preventing platform vibration from being transmitted to the vacuum cover 100.

[0084] The rigid second support rod 131, the third support rod 132, and the rigid connecting plate 133 work together to keep the support position stable and prevent tilting or loosening even when the system cools down and the components shrink, thus ensuring the long-term safe operation of the system.

[0085] According to one embodiment of the present invention, it further includes a first-stage cold shield 116 and a second-stage cold shield 118, both of which are disposed inside the vacuum chamber 100 and surround the resonant cavity 102.

[0086] In one embodiment of the present invention, the first-stage cold shield 116 and the second-stage cold shield 118 are both cylindrical structures, disposed inside the vacuum shroud 100, and both surround the resonant cavity 102. The first-stage cold shield 116 is located on the outside and the second-stage cold shield 118 is located on the inside, with a preset gap between them to form a double-layer radiation heat insulation structure.

[0087] The outer periphery of the first-stage cold shield 116 is wrapped with multiple layers of thermal insulation material to block radiative heat leakage from the inner wall of the vacuum chamber 100. The inner periphery of the second-stage cold shield 118 maintains a small gap with the outer periphery of the resonant cavity 102, and its outer periphery surface is gold-plated to block radiative heat leakage from the first-stage cold shield 116. The height of the cold shield is adapted to the resonant cavity 102 to ensure complete coverage of the side periphery of the resonant cavity 102, with no dead zones for radiative heat leakage. The cold shield is made of a high thermal conductivity metal to facilitate rapid reception of the cooling energy transferred from the refrigerator and maintain a low temperature.

[0088] The first-stage cold shield 116 blocks the high-temperature radiation from the vacuum chamber 100, and the second-stage cold shield 118 blocks the low-temperature radiation from the first-stage cold shield 116. The double insulation greatly reduces the impact of radiation heat leakage on the resonant cavity 102, so that the temperature of the resonant cavity 102 is stabilized at the preset test temperature.

[0089] The low-temperature barrier formed by the double-layer cold shield prevents external heat from directly acting on the resonant cavity 102. Especially in wide-temperature testing, it can quickly respond to temperature adjustment needs, so that the temperature of the resonant cavity 102 changes smoothly and meets the testing accuracy requirements of different temperature zones.

[0090] The reduction in heat leakage allows the GM refrigerator to use more of its cooling capacity to maintain the low temperature of the resonant cavity 102 and the sample holder 104, rather than to offset external heat leakage, thereby improving the refrigerator's efficiency and shortening the time it takes for the system to cool down to the target temperature.

[0091] According to one embodiment of the present invention, the GM refrigeration unit 106 includes a first GM refrigeration unit 124 and a second GM refrigeration unit 126;

[0092] The first stage cold head 120 of the first GM refrigerator 124 and the first stage cold head 120 of the second GM refrigerator 126 are flexibly connected to the first stage cold screen 116 through a flexible heat-conducting copper strip 114 to cool the first stage cold screen 116, reduce the vibration of the first stage cold screen 116 and reduce radiative heat leakage from the vacuum chamber 100.

[0093] The second-stage cold head 122 of the first GM refrigerator 124 is connected to the second-stage cold screen 118 through a flexible heat-conducting copper strip 114 to provide cooling to the second-stage cold screen 118, thereby reducing vibration of the second-stage cold screen 118 and reducing radiative heat leakage from the first-stage cold screen 116 while indirectly cooling the resonant cavity 102.

[0094] The second stage cold head 122 of the second GM refrigerator 126 is connected to the sample holder 104 via a flexible thermally conductive copper strip 114 to provide cooling to the sample holder 104 and reduce vibration of the sample holder 104.

[0095] In one embodiment of the present invention, the GM refrigeration unit 106 includes a first GM refrigeration unit 124 and a second GM refrigeration unit 126, both of which have the same structure and are equipped with a first-stage cold head 120 and a second-stage cold head 122. The temperature of the first-stage cold head 120 is higher than that of the second-stage cold head 122, which can adapt to different cooling capacity requirements.

[0096] The first-stage cold head 120 of the first GM refrigerator 124 and the first-stage cold head 120 of the second GM refrigerator 126 are respectively connected to the outer peripheral wall of the first-stage cold screen 116 through multiple flexible heat-conducting copper strips 114. The flexible heat-conducting copper strips 114 are evenly distributed around the first-stage cold screen 116, and both ends of the flexible heat-conducting copper strips 114 are fixed to the first-stage cold head 120 and the first-stage cold screen 116 respectively by bolts. The flexible heat-conducting copper strips 114 have a certain degree of elasticity and can move with the first-stage cold head 120. The head 120 vibrates and deforms slightly; the second-stage cold head 122 of the first GM refrigerator 124 is connected to the outer peripheral wall of the second-stage cold screen 118 through a flexible heat-conducting copper strip 114, and the connection method is the same as that of the first-stage cold screen 116; the second-stage cold head 122 of the second GM refrigerator 126 is connected to the side wall of the sample holder 104 through a flexible heat-conducting copper strip 114. The length of the flexible heat-conducting copper strip 114 is adapted to the distance between the sample holder 104 and the cold head to ensure that the sample holder 104 can stably receive cold energy.

[0097] The flexible thermally conductive copper strip 114 is made of high-purity copper, which has excellent thermal conductivity. At the same time, the copper strip has good flexibility, ensuring good elastic deformation ability and reducing vibration.

[0098] The flexible thermally conductive copper strip 114 absorbs the vibration of the GM refrigeration unit 106 through its own elasticity, preventing the vibration from being transmitted to the first-stage cold shield 116, the second-stage cold shield 118 and the sample holder 104, and preventing the first-stage cold shield 116 and the second-stage cold shield 118 from deforming due to vibration or the sample holder 104 from shifting due to vibration, thus ensuring a stable testing environment.

[0099] The high thermal conductivity of the flexible thermally conductive copper strip 114 allows the cold energy of the cold head to be quickly transferred to the cold screen and sample holder 104. The first-stage cold screen 116 and the second-stage cold screen 118 can be quickly cooled to the target temperature. The temperature of the sample holder 104 can also be flexibly adjusted within different ranges to adapt to the test temperature requirements of different samples.

[0100] The first-stage cold shield 116 and the second-stage cold shield 118 maintain low temperatures under the cooling effect of the copper strip, further blocking external radiation heat leakage, reducing the temperature fluctuation amplitude of the resonant cavity 102 and the sample holder 104, and improving the repeatability and accuracy of the test data.

[0101] According to one embodiment of the present invention, it further includes a plurality of heat-insulating support columns 127. The first-stage cold shield 116, the second-stage cold shield 118 and the sample holder 104 are mounted on the vacuum chamber 100 through the heat-insulating support columns 127, and the first-stage cold shield 116, the second-stage cold shield 118 and the sample holder 104 are heat-insulated from the vacuum chamber 100 through the heat-insulating support columns 127.

[0102] In one embodiment of the present invention, the heat-insulating support column 127 is a rod-shaped structure, made of an insulating material with low thermal conductivity (such as G10 material), possessing good mechanical strength and low-temperature resistance. Multiple heat-insulating support columns 127 are evenly distributed along the circumference of the first-stage cold shield 116, with one end fixedly connected to the outer peripheral wall of the first-stage cold shield 116 by bolts, and the other end fixedly connected to the inner wall of the vacuum chamber 100, thus supporting the first-stage cold shield 116.

[0103] The support method of the second-stage cold shield 118 is the same as that of the first-stage cold shield 116; the sample holder 104 is also connected to the inner wall of the vacuum chamber 100 through the heat insulation support column 127. The length of the heat insulation support column 127 is adapted to the distance between the sample holder 104 and the vacuum chamber 100, ensuring that the sample holder 104 is located at a preset position outside the resonant cavity 102.

[0104] All thermal insulation support columns 127 have a diameter and length adapted to support the weight, preventing bending or breakage.

[0105] The low thermal conductivity of G10 material significantly reduces the heat transfer from the inner wall of the vacuum chamber 100 to the cold screen and sample holder 104 via the support columns, thus preventing the loss of cold energy due to heat leakage.

[0106] The mechanical strength of the thermal insulation support column 127 can stably support the weight of the cold screen and the sample holder 104. Even when the system cools down and the components shrink thermally, the support column can maintain a stable connection and prevent the cold screen or sample holder 104 from tilting or shaking. This ensures that the relative position of the resonant cavity 102 and the sample holder 104 is fixed and the test is not affected.

[0107] G10 material exhibits excellent low-temperature resistance, without becoming embrittled or experiencing performance degradation within a wide temperature range of 4K-300K. It maintains good thermal insulation and support properties even after long-term use, extending the overall service life of the system.

[0108] According to one embodiment of the present invention, the sample rod assembly 110 includes a dynamic sealing structure 134, and a valve 136 is provided on the vacuum shroud 100;

[0109] The internal space of the vacuum hood 100 is divided into a main chamber 138 and a transition chamber 140 by a valve 136. The sample rod assembly 110 is inserted into the transition chamber 140 through the dynamic sealing structure 134. The valve 136 is adapted to switch between an open state and a closed state. In the open state, the main chamber 138 and the transition chamber 140 are interconnected. In the closed state, the main chamber 138 and the transition chamber 140 are isolated from each other.

[0110] In one embodiment of the present invention, a valve 136 is installed on the side wall of the vacuum chamber 100. The valve 136 is an electromagnetically controlled valve that can switch between open and closed states. The valve 136 divides the internal space of the vacuum chamber 100 into a main cavity 138 near the resonant cavity 102 and a transition cavity 140 near the sample rod assembly 110. The main cavity 138 is used to maintain the low-temperature vacuum environment of the resonant cavity 102 and the sample holder 104, and the transition cavity 140 is used for temporary sample transfer.

[0111] The dynamic sealing structure 134 of the sample rod assembly 110 is fixedly installed on the side wall of the corresponding transition cavity 140 of the vacuum chamber 100. A through hole is opened in the center of the dynamic sealing structure 134, and the rod of the sample rod assembly 110 can move or rotate axially along the through hole. At the same time, the dynamic sealing structure 134 can maintain the vacuum seal of the transition cavity 140. When it is necessary to change the sample, the valve 136 is closed to isolate the main cavity 138 from the transition cavity 140. After the transition cavity 140 is evacuated independently, the valve 136 is opened, and the sample rod assembly 110 can move in the connected cavity to complete the sample loading and unloading. The vacuum and low temperature environment of the main cavity 138 are not affected during the entire process.

[0112] After valve 136 is closed, the main cavity 138 and the transition cavity 140 are completely isolated. When changing samples, temperature fluctuations and air in the transition cavity 140 will not enter the main cavity 138, ensuring the stability of the vacuum level and low temperature environment in the main cavity, avoiding additional energy consumption caused by the system to be cooled or re-vacuumed, and protecting the low temperature state of the resonant cavity 102 from being damaged.

[0113] The transition chamber 140 eliminates the need to wait for the main chamber 138 to cool down or be evacuated before sample replacement. Only a simple treatment of the transition chamber 140 is required, which greatly shortens the sample replacement time and is especially suitable for multi-sample continuous testing scenarios, thus improving testing efficiency.

[0114] The transition cavity 140 serves as a buffer zone, allowing heat from the external environment to enter only and preventing it from being transferred to the main cavity 138. This minimizes temperature fluctuations within the main cavity, ensuring that the temperatures of the resonant cavity 102 and the sample holder 104 remain stable within the required testing range and guaranteeing accurate test data.

[0115] According to one embodiment of the present invention, the dynamic sealing structure 134 includes a dynamic sealing body 142, a dynamic sealing ring 144, and a sealing nut 146 for pressing the dynamic sealing ring 144;

[0116] The rod of the sample rod assembly 110 passes through the dynamic sealing ring 144 to form a dynamic seal.

[0117] The dynamic sealing body 142 is a metal cylindrical structure, installed on the top of the vacuum hood 100, with a through hole in the center of the body that is adapted to the rod of the sample rod assembly 110.

[0118] The dynamic sealing ring 144 is an annular structure made of elastic material, which is sleeved on the rod body of the sample rod assembly 110 and located outside the through hole of the dynamic sealing body 142.

[0119] The sealing nut 146 is a metal ring structure, which is connected to the end of the dynamic sealing body 142 by threads. When the sealing nut 146 is tightened, the nut will squeeze the dynamic sealing ring 144, so that the sealing ring fits tightly against the rod body and the inner wall of the through hole, forming a dynamic seal.

[0120] The rod of the sample rod assembly 110 can move or rotate along the through hole axially. The dynamic sealing ring 144 always maintains a tight fit during the movement of the rod without any gaps. The sealing ring is made of a low-temperature resistant elastic material that does not harden or become brittle in a wide temperature range, ensuring long-term sealing performance.

[0121] The tight fit structure formed by the sealing nut 146 pressing the sealing ring 144 can effectively prevent external air from entering the transition cavity 140, while reducing the intrusion of external heat through the gap between the rod and the sealing ring, maintaining the vacuum and low temperature environment of the transition cavity 140, and providing a guarantee for the subsequent isolation of the main cavity 138.

[0122] The elasticity of the dynamic sealing ring 144 allows the rod of the sample rod assembly 110 to move or rotate freely without affecting the sample handling operation. At the same time, the sealing performance is not affected by the movement of the rod, avoiding sealing failure caused by operation and improving the reliability of the sample changing process.

[0123] According to one embodiment of the present invention, the sample rod assembly 110 includes:

[0124] Hollow rod 148 is used to reduce thermal conductivity and heat leakage of sample rod assembly 110;

[0125] The sample holder 150 is disposed at one end of the hollow rod 148, and the sample holder 150 is adapted to be detachably connected to the sample seat 104 via a first threaded structure.

[0126] The low-temperature end connector 152 is connected between the hollow rod body 148 and the sample holder 150. The low-temperature end connector 152 and the sample holder 150 are connected by a second thread structure. The rotation direction of the second thread structure is opposite to that of the first thread structure, so that the unidirectional rotation of the hollow rod body 148 can sequentially tighten the sample holder 150 and the sample seat 104, and separate the low-temperature end connector 152 from the sample holder 150.

[0127] A gemstone pillar 154 is mounted on a sample holder 150 so that the sample holder 104 cools the sample holder 150, the gemstone pillar 154, and the sample on the gemstone pillar 154.

[0128] In one embodiment of the present invention, the hollow rod 148 of the sample rod assembly 110 is a tubular structure made of a low thermal conductivity metal (e.g., stainless steel) with a hollow interior to reduce the thermal conductivity area of ​​the rod and reduce the heat transferred from the outside to the inside of the cavity through the rod; the length of the hollow rod 148 is adapted to the thickness of the vacuum shroud 100 to ensure that one end can extend to the outside for operation and the other end can enter the transition cavity 140.

[0129] The sample holder 150 is a columnar structure made of oxygen-free copper and is located at one end of the hollow rod 148. The outer periphery of the sample holder 150 is provided with a first thread structure, which is adapted to the thread at the bottom of the sample seat 104 to realize the detachable connection between the sample holder 150 and the sample seat 104. The low-temperature end connector 152 is a columnar structure made of metal and is connected between the hollow rod 148 and the sample holder 150. One end of the connector is fixed to the hollow rod 148, and the other end is provided with a second thread structure, which is adapted to the thread at the top of the sample holder 150, and the direction of rotation of the second thread structure is opposite to that of the first thread structure.

[0130] The gemstone pillar 154 is installed at the bottom of the sample holder 150 to support the sample to be tested. When the hollow rod 148 is rotated in one direction, the sample holder 150 is first tightened to the sample seat 104 through the first thread structure to achieve close contact between the sample holder 150 and the sample seat 104 to transfer cold energy. If the rotation continues, the low temperature end connector 152 is separated from the sample holder 150 through the second thread structure, so that the sample holder 150 can remain on the sample seat 104 and the hollow rod 148 can be removed separately.

[0131] The hollow rod 148 reduces the heat conduction area, significantly reducing the heat transferred from the outside to the inside of the cavity through the hollow rod 148, preventing the low temperature environment of the cavity from being destroyed, and ensuring that the sample holder 150, the sapphire pillar 154 and the sample can quickly reach the test temperature.

[0132] The first thread tightening ensures that the sample holder 150 and the sample base 104 are in close contact, and the cold energy can be efficiently transferred to the sample holder 150, the sapphire pillar 154 and the sample, meeting the requirements of low temperature testing. The reverse thread design prevents the sample holder 150 from becoming loose when the connector is separated, avoids the sample holder 150 from vibrating and causing the sample to shift, and reduces the vibration transmission during the separation process, protecting the relative position stability of the sample and the resonant cavity 102.

[0133] The separate design of the sample holder 150 and the connector allows the hollow rod 148 to be removed independently, so that the solid thermal leakage only affects the sample holder for a short time, avoiding system losses caused by prolonged damage to the low-temperature environment.

[0134] See Figure 7 A second aspect of the present invention provides a testing method for a cryogenic resonant cavity system as described above, comprising:

[0135] Step 10, Background test procedure: Under the condition that the sapphire column 154 is not loaded with the sample to be tested, the main cavity 138 of the resonant cavity low temperature system is evacuated and cooled to the preset test temperature using the GM refrigeration unit 106, and the first microwave response of the resonant cavity 102 is tested.

[0136] Step 20, Sample online loading step: Close valve 136 to isolate the main chamber 138 and the transition chamber 140, insert sample rod assembly 110, independently evacuate the transition chamber 140 to a vacuum, open valve 136, use sample rod assembly 110 to remove sample holder 150 with gemstone column 154 installed from sample seat 104 and move it to transition chamber 140, close valve 136, remove sample rod assembly 110 from the cryogenic system, load the sample to be tested onto gemstone column 154, reinsert sample rod assembly 110 into transition chamber 140 and independently evacuate transition chamber 140, open valve 136, install sample holder 150 with sample to be tested onto sample seat 104, separate sample holder 150 and sample rod cryogenic end connector 152, move to transition chamber 140, close valve 136, and remove sample rod assembly 110. Throughout the process, the vacuum and cryogenic environment of the main chamber 138 are maintained.

[0137] Step 30, Sample testing steps: After the temperature of the sample to be tested reaches the preset test temperature, test the second microwave response of the resonant cavity 102 after the sample to be tested is loaded.

[0138] Step 40, Characteristic Calculation Step: Calculate the microwave surface resistance of the sample under test based on the first microwave response and the second microwave response.

[0139] According to the test method of the resonant cavity cryogenic system provided in the second aspect embodiment of the present invention, in the background test step, the main cavity 138 is evacuated to form a vacuum environment, which can reduce the transfer of external heat to the main cavity 138 and prevent the internal cold energy of the main cavity 138 from dissipating to the outside, thus preventing heat leakage. The GM refrigeration unit 106 continuously transfers cold energy to ensure that the main cavity 138 can stably drop to and maintain at the preset test temperature, providing the necessary low temperature conditions for accurate testing of the first microwave response. In the sample online loading step, the main cavity 138 and the transition cavity 140 are isolated multiple times by the valve 136, so that the main cavity 138 always maintains a closed vacuum and low temperature environment during operations such as evacuation of the transition cavity 140, insertion and removal of the sample rod assembly 110, and sample loading, effectively preventing external heat from entering the main cavity 138, preventing cold energy leakage of the main cavity 138, and ensuring that the low temperature state of the main cavity 138 is not damaged. The independent vacuuming operation of the transition chamber 140 also reduces heat exchange when the transition chamber 140 is connected to the main chamber 138, further helping to prevent heat leakage and maintain the low temperature of the main chamber 138. Throughout the test, the GM refrigerator unit 106 continuously plays a role in transferring cold energy. In the background test step, the GM refrigerator unit 106 transfers cold energy to the main chamber 138, causing the main chamber 138 to drop to the preset test temperature. After the sample is loaded online, the GM refrigerator unit 106 continues to transfer cold energy to the main chamber 138 and the sample holder 104, sample tray 150, and the sample to be tested inside, ensuring that the sample to be tested can be quickly reduced to the preset test temperature and maintain temperature stability during the sample test step, providing the necessary low-temperature conditions for accurate testing of the second microwave response. In each step of the test method, the GM refrigerator unit 106 is always in operation to maintain the low-temperature environment, and the mechanical vibration damping component 108 continuously isolates the mechanical vibration generated by the GM refrigerator unit 106 during operation. This isolation prevents vibration from being transmitted to the resonant cavity 102, sample holder 104, sample tray 150, and the sample under test inside the main cavity 138. This reduces the interference of vibration on the microwave response test of the resonant cavity 102, ensuring that the sample is loaded and tested in a stable environment. This improves the accuracy of the first and second microwave response test data, thus providing support for the accuracy of subsequent microwave surface resistance calculations. The first microwave response acquired in the background test step can eliminate the influence of the main cavity 138's own environment (when there is no sample under test) on the microwave response of the resonant cavity 102, providing a background reference for subsequent sample testing. The continuous maintenance of the vacuum and low temperature environment of the main cavity 138 during the online sample loading step, and the stabilization of the sample temperature at the preset test temperature during the sample testing step, ensure that the second microwave response only reflects the influence of the sample under test on the resonant cavity 102. Based on the comparison calculation of the first and second microwave responses, background interference factors can be effectively eliminated, significantly improving the accuracy and reliability of the microwave surface resistance calculation results of the sample under test.

[0140] Please continue reading Figure 7 The testing method for a cryogenic resonant cavity system consists of four core steps:

[0141] Step 10, Background Testing Procedure:

[0142] With the sapphire column 154 unloaded, a vacuum operation is performed on the main cavity 138 of the resonant cavity cryogenic system to create a vacuum environment inside the main cavity 138. Subsequently, the GM refrigerator unit 106 is activated, transferring cooling energy to the main cavity 138 and its internal components to lower the internal temperature of the main cavity 138 to the preset test temperature. After the temperature stabilizes, the first microwave response of the resonant cavity 102 is measured using the corresponding detection device, completing the acquisition of background data.

[0143] It should be noted that, in the embodiments of the present invention, the example of a bulk single crystal is used for explanation and illustration. The testing method provided in the embodiments of the present invention can also be applied to the detection of thin film samples.

[0144] When testing thin film samples, replace the sapphire pillar 154 with the dielectric material corresponding to its substrate, such as magnesium oxide.

[0145] Step 20, Sample online loading steps:

[0146] First, close valve 136 in the system to isolate the main chamber 138 from the transition chamber 140, preventing the environment of the main chamber 138 from being affected by subsequent operations in the transition chamber 140. Next, insert the sample rod assembly 110 into the corresponding interface of the transition chamber 140. Then, independently evacuate the transition chamber 140 to achieve a preset vacuum state. After evacuating the transition chamber 140, open the previously closed valve 136 to restore communication between the main chamber 138 and the transition chamber 140.

[0147] Using the operating function of the sample rod assembly 110, the sample holder 150, on which the gemstone pillar 154 is mounted, is removed from the sample seat 104 inside the main cavity 138, and then moved into the transition cavity 140 via the sample rod assembly 110. Subsequently, valve 136 is closed again, re-isolating the main cavity 138 from the transition cavity 140. The sample rod assembly 110 is then removed from the cryogenic system, at which point the sample holder 150 is located outside the transition cavity 140 along with the sample rod assembly 110.

[0148] The sample to be tested is loaded onto the gemstone pillar 154, completing the assembly of the sample and the gemstone pillar 154. Then, the sample rod assembly 110 is reinserted into the interface of the transition chamber 140, and the transition chamber 140 is independently evacuated to ensure that it reaches the preset vacuum state again. After evacuation, valve 136 is opened to restore the connection between the main chamber 138 and the transition chamber 140. The sample holder 150, containing the sample to be tested, is then installed back onto the sample holder 104 inside the main chamber 138 via the sample rod assembly 110.

[0149] After the sample holder 150 is installed, it is separated from the cryogenic connector 152 of the sample rod assembly 110. The separated cryogenic connector 152 is then moved into the transition chamber 140 via the sample rod assembly 110. Subsequently, valve 136 is closed to re-isolate the main chamber 138 from the transition chamber 140. Finally, the sample rod assembly 110 is removed from the cryogenic system. Throughout the entire online sample loading process, the main chamber 138 maintains a vacuum and cryogenic environment.

[0150] Step 30, Sample Testing Procedure:

[0151] After the online loading of the sample is completed, wait for the temperature of the sapphire pillar 154 with the sample to be tested inside the main cavity 138 to drop to the preset test temperature. After the temperature stabilizes, use a detection device to test the second microwave response of the resonant cavity 102 with the sample to be tested, and complete the acquisition of relevant sample data.

[0152] Step 40, Characteristic Calculation Steps:

[0153] The first microwave response data obtained from the background testing step and the second microwave response data obtained from the sample testing step are acquired. Based on these two sets of microwave response data, the microwave surface resistance of the sample under test is calculated using the corresponding calculation methods, thus completing the analysis of the sample's characteristics.

[0154] It should be noted that in the steps described above, the test object is a bulk single crystal. When it is necessary to change the sample for testing, for example, when changing to another type of bulk single crystal, simply repeat steps 20 to 40 above.

[0155] When it is necessary to test a thin film sample, simply replace the sapphire pillar 154 in steps 10 to 40 above with the dielectric material corresponding to its substrate, such as magnesium oxide.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A resonator cryogenic system, characterized by, The application relates to a vacuum chamber (100) comprising: a vacuum chamber (100); a resonant cavity (102) arranged inside the vacuum chamber (100); a sample holder (104) arranged outside the resonant cavity (102); at least one GM refrigerator unit (106) for providing cold energy for the resonant cavity (102) or the sample holder (104); a mechanical vibration isolation assembly (108) configured to isolate mechanical vibrations generated when the GM refrigerator unit (106) is in operation, the mechanical vibration isolation assembly (108) further comprising an optical vibration isolation platform (128), a plurality of first support rods (130), a second support rod (131) and a third support rod (132), the vacuum chamber (100) is supported on the ground by the first support rods (130) to form a non-contact support between the vacuum chamber (100) and the optical vibration isolation platform (128), one end of the second support rod (131) is connected to the GM refrigerator unit (106), the other end of the second support rod (131) is connected to a rigid connecting plate (133), one end of the third support rod (132) is connected to the optical vibration isolation platform (128), and the other end of the third support rod (132) is connected to the rigid connecting plate (133) to transmit the vibration of the GM refrigerator unit (106) to the optical vibration isolation platform (128); a sample rod assembly (110) adapted to be inserted into the vacuum chamber (100) to deliver a sample to be measured to the sample holder (104) and the resonant cavity (102).

2. The resonator cryogenic system of claim 1, wherein, The mechanical vibration isolation assembly (108) comprises a flexible bellows (112), one end of the flexible bellows (112) is connected to the GM refrigerator unit (106), and the other end of the flexible bellows (112) is connected to the vacuum chamber (100) to vacuum seal the vacuum chamber (100) while isolating the mechanical vibrations.

3. The resonator cryogenic system of claim 1, wherein, Further comprising a first-stage cold shield (116) and a second-stage cold shield (118), the first-stage cold shield (116) and the second-stage cold shield (118) are arranged inside the vacuum chamber (100) and surround the resonant cavity (102).

4. The resonator cryogenic system of claim 3, wherein, The GM refrigerator unit (106) comprises a first GM refrigerator (124) and a second GM refrigerator (126); The first-stage cold head (120) of the first GM refrigerator (124) and the first-stage cold head (120) of the second GM refrigerator (126) are flexibly connected with the first-stage cold shield (116) through flexible heat-conducting copper belts (114) to cool the first-stage cold shield (116), realize vibration reduction of the first-stage cold shield (116) and reduce radiation heat leakage from the vacuum shell (100); the second-stage cold head (122) of the first GM refrigerator (124) is connected with the second-stage cold shield (118) through a flexible heat-conducting copper belt (114) to provide cold energy for the second-stage cold shield (118), realize vibration reduction of the second-stage cold shield (118) and reduce radiation heat leakage from the first-stage cold shield (116) while indirectly cooling the resonant cavity (102); The second-stage cold head (122) of the second GM refrigerator (126) is connected with the sample holder (104) through a flexible heat-conducting copper belt (114) to provide cold energy for the sample holder (104) and realize vibration reduction of the sample holder (104).

5. The resonator cryogenic system of claim 4, wherein, A plurality of heat-insulating support columns (127) are further included, the first-stage cold shield (116), the second-stage cold shield (118) and the sample holder (104) are mounted to the vacuum shell (100) through the heat-insulating support columns (127), and the first-stage cold shield (116), the second-stage cold shield (118) and the sample holder (104) realize heat insulation from the vacuum shell (100) through the heat-insulating support columns (127).

6. The resonator cryogenic system of any one of claims 1 to 5, wherein, The sample rod assembly (110) comprises a dynamic sealing structure (134), and the vacuum shell (100) is provided with a valve (136); An internal space of the vacuum shell (100) is divided into a main cavity (138) and a transition cavity (140) by the valve (136), the sample rod assembly (110) is inserted into the transition cavity (140) through the dynamic sealing structure (134), and the valve (136) is adapted to be switched between an open state and a closed state, in the open state, the main cavity (138) and the transition cavity (140) are in communication with each other, and in the closed state, the main cavity (138) and the transition cavity (140) are isolated from each other.

7. The resonator cryogenic system of claim 6, wherein, The dynamic sealing structure (134) comprises a dynamic sealing body (142), a dynamic sealing ring (144) and a sealing nut (146) for pressing the dynamic sealing ring (144); A rod body of the sample rod assembly (110) is arranged in the dynamic sealing ring (144) to constitute a dynamic seal.

8. The resonator cryogenic system of claim 6, wherein, The sample rod assembly (110) comprises: A hollow rod body (148) for reducing heat conduction heat leakage of the sample rod assembly (110); A sample holder (150) arranged at one end of the hollow rod body (148), the sample holder (150) is adapted to be detachably connected with the sample holder (104) through a first threaded structure; A low-temperature end connector (152) is connected between the hollow rod (148) and the sample holder (150), and is connected with the sample holder (150) through a second threaded structure, the rotation direction of the second threaded structure being opposite to that of the first threaded structure, so that one-way rotation of the hollow rod (148) can sequentially achieve the tightening of the sample holder (150) and the sample seat (104), and the separation of the low-temperature end connector (152) and the sample holder (150); A gem column (154) is installed on the sample holder (150), so that the sample seat (104) cools the sample holder (150), the gem column (154), and the sample on the gem column (154).

9. A method of testing a resonator cryogenic system as claimed in claim 8, characterized in that, It comprises: A background test step: under the condition that the gem column is not loaded with the sample to be tested, the main cavity (138) of the resonant cavity cryogenic system is vacuumized and cooled to a preset test temperature by the GM refrigerator unit (106), and the first microwave response of the resonant cavity (102) is tested; A sample online loading step: close the valve (136) to isolate the main cavity (138) and the transition cavity (140), insert the sample rod assembly (110), vacuumize the transition cavity (140) independently, open the valve (136), use the sample rod assembly (110) to remove the sample holder (150) with the gem column (154) from the sample seat (104) and move it to the transition cavity (140), close the valve (136), remove the sample rod assembly (110) from the cryogenic system, load the sample to be tested onto the gem column (154), reinsert the sample rod assembly (110) into the transition cavity (140) and vacuumize the transition cavity (140) independently, open the valve (136), and install the sample holder (150) loaded with the sample to be tested onto the sample seat (104), separate the sample holder (150) and the low-temperature end connector, move to the transition cavity (140), close the valve (136), and remove the sample rod assembly (110), during the whole process, the vacuum and low-temperature environment of the main cavity (138) are maintained; A sample test step: after the temperature of the sample to be tested reaches the preset test temperature, the second microwave response of the resonant cavity (102) loaded with the sample to be tested is tested; A characteristic calculation step: based on the first microwave response and the second microwave response, the microwave surface resistance of the sample to be tested is calculated.

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