Double-layer sample rod suitable for extremely low temperature test in pulsed magnet liquid helium Dewar

Abstract

The invention belongs to the technical field of extremely low temperature tests, and particularly discloses a double-layer sample rod suitable for an extremely low temperature test in a pulsed magnet liquid helium Dewar, which comprises a first rod section, a second rod section and a switching assembly, the first rod section comprises a first outer pipe and a first inner pipe which are coaxially arranged in a sleeved mode, a condensation layer is formed between the first outer pipe and the first inner pipe, and a vacuum layer is formed in the first inner pipe. The second rod section comprises a second outer pipe and a second inner pipe which are coaxially sleeved, a feeding port is formed in the upper end of the second outer pipe, the lower end of the second outer pipe is sealed, a sample cavity is formed between the second outer pipe and the second inner pipe, and a sample clamp is hermetically mounted at the lower end of the second inner pipe; the switching assembly comprises a first switching piece, a condensation pipe, a second switching piece and a sealing plate. According to the structural design, the extremely low temperature condition is guaranteed, and controllable thermal isolation between the sample cavity and the external refrigerating working medium serving as a cold source is effectively achieved.

Description

Technical Field

[0001] This application belongs to the field of cryogenic testing technology, and more specifically, relates to a double-layer sample rod suitable for cryogenic testing in a pulsed magnet liquid helium Dewar. Background Technology

[0002] By applying high-intensity transient magnetic fields, the electronic structure of materials can be effectively modulated, thereby inducing significant changes in their magnetic, thermal, optical, and electrical physical properties. Meanwhile, extremely low temperatures (liquid helium temperature range, approximately 0–5 K) are crucial conditions for discovering and studying novel states of matter such as superconductivity and quantum phase transitions. Combining pulsed strong magnetic fields with extremely low temperature technology aims to explore the evolution of material properties under dual extreme conditions and reveal the underlying microscopic physical mechanisms, which is of great significance for advancing research on cutting-edge scientific issues.

[0003] To achieve the above objectives, the experimental setup must simultaneously meet two stringent conditions: first, it must be compatible with the limited narrow aperture of the pulse magnet; second, it must provide a stable and reliable cryogenic experimental environment. The conventional approach involves placing the sample rod inside a liquid helium Dewar (a high-vacuum insulated container specifically designed for storing and transporting cryogenic liquid helium), and cooling it with liquid helium (helium-4). Helium-4 has a liquefaction temperature of 4.2 K at atmospheric pressure, and through decompression cooling techniques, it can be reduced to as low as approximately 1.4 K, which meets the cryogenic requirements of most basic research.

[0004] To achieve even lower temperature ranges (on the order of mK), scarce and expensive helium-3 must be used as the refrigerant. However, due to cost and control accuracy considerations, helium-3 is usually not directly introduced into the main liquid helium dewar. In addition, when measuring samples that are extremely sensitive to thermal disturbances, such as those with magnetic card effects, specific heat, and thermal conductivity, directly immersing the sample in liquid helium-3 will introduce strong thermal fluctuations, which will seriously affect the accuracy of the measurement. Summary of the Invention

[0005] In response to the deficiencies or improvement needs of existing technologies, this application provides a double-layer sample rod suitable for ultra-low temperature testing in a pulsed magnet liquid helium Dewar, aiming to solve the problem that existing sample rods cannot provide a reliable ultra-low temperature environment for the sample while ensuring controllable thermal isolation between the sample chamber and the refrigerant.

[0006] This application provides a double-layer sample rod suitable for ultra-low temperature testing of pulsed magnet liquid helium Dewar, comprising a first rod section, a second rod section, and a transition assembly; The first rod segment includes a first outer tube and a first inner tube coaxially sleeved together. A condensation layer is formed between the first outer tube and the first inner tube. The upper end of the first inner tube is provided with an air extraction port and the lower end extends out of the first outer tube. A vacuum layer is formed inside the first inner tube. The second rod segment includes a second outer tube and a second inner tube coaxially sleeved together. The upper end of the second outer tube is provided with a feeding port and the lower end is sealed. A sample cavity is formed between the second outer tube and the second inner tube. A sample clamp is sealed and installed at the lower end of the second inner tube. A condensation cavity is formed inside the second inner tube. The adapter assembly includes a first adapter, a condenser tube, a second adapter, and a sealing plate. The first adapter seals the lower end of the first outer tube, and the second adapter seals the upper end of the second inner tube. The condenser tube connects the first adapter and the second adapter, allowing the condensation layer and the condensation chamber to communicate. The sealing plate is fitted onto the outside of the first inner tube and is detachably and sealingly connected to the feed port.

[0007] As a further preferred embodiment, the first adapter has a first adapter cavity inside, the second adapter has a second adapter cavity inside, and the condenser tube connects the first adapter cavity and the second adapter cavity.

[0008] As a further preferred embodiment, the first adapter has a first upper interface at its upper end and a first lower interface at its lower end, the first adapter cavity is located between the first upper interface and the first lower interface, the lower end of the first outer tube is sealed to the first upper interface, the lower end of the first inner tube passes through the first upper interface and the first lower interface in sequence, and the outer wall of the first inner tube is sealed to the inner wall of the first lower interface. The lower end of the first adapter also has a first adapter interface located on one side of the first lower interface.

[0009] As a further preferred embodiment, the lower end of the second adapter is provided with a second lower end interface that is sealed and connected to the upper end of the second inner tube, and the upper end of the second adapter is provided with a second adapter interface that is connected to the condenser tube, and the second adapter cavity is located between the second lower end interface and the second adapter interface.

[0010] As a further preferred embodiment, the number of condenser tubes is two, and they are symmetrically arranged on both sides of the first inner tube.

[0011] As a further preferred embodiment, the condenser tube is a rigid metal tube that penetrates the sealing plate and is fixedly connected to the sealing plate.

[0012] As a further preferred embodiment, a sealing connector is fixed to the upper end of the second outer tube, and a sealing connection platform is formed at the upper end of the sealing connector. The sealing plate and the sealing connection platform are detachably connected, and the end face of the sealing connection platform is provided with a sealing groove for installing a sealing element.

[0013] As a further preferred embodiment, the seal is a sealing ring made of pure indium or an indium-based alloy.

[0014] As a further preferred embodiment, the upper end of the first rod segment is provided with an air inlet connector, the first inner tube passes through the air inlet connector, and the air inlet connector is connected to an air inlet pipe that communicates with the condensation layer.

[0015] As a further preferred embodiment, the air inlet connector and the sealing plate are respectively equipped with a first lead plate and a second lead plate. The lead connecting the lower end of the first lead plate and the upper end of the second lead plate is located outside the first outer tube, and the lead connecting the lower end of the second lead plate is located in the sample chamber. The outer sides of both the first adapter and the second adapter are formed with clearance grooves for making way for the lead.

[0016] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages: 1. The double-layer sample rod provided in this application connects a first rod segment with a condensation layer and a vacuum layer, and a second rod segment with a sample cavity and a condensation cavity, via an adapter assembly. This allows the flow path (condensation layer and condenser tube) of helium gas entering from the upper end of the first outer tube within the first rod segment and adapter assembly section to fully exchange heat with the liquid helium in the external liquid helium Dewar. Upon entering the condensation cavity, the gas exchanges heat with the sample holder in the form of extremely low-temperature liquid helium, thus creating a stable and reliable extremely low-temperature environment for the sample to be tested. Furthermore, the sample cavity containing the sample is located outside the condensation cavity and is connected to the vacuum layer. When the vacuum layer is evacuated from the first inner tube, a high-vacuum environment is simultaneously formed in the sample cavity. The structural design of this application not only ensures the achievement of extremely low-temperature conditions but also effectively achieves controllable thermal isolation between the sample cavity and the external refrigerant serving as the cold source.

[0017] 2. The structure design adopts a first and second adapter to form an adapter cavity. The two adapter cavities are connected by a condenser tube. This not only achieves smooth communication between the condensation layer and the condensation cavity, ensuring the continuity of the cryogenic helium transport path, but also optimizes the airflow distribution and enhances the overall heat exchange efficiency through the buffering and transition function of the adapter cavity. At the same time, the compact layout of the adapter can further improve the stability of the ultra-low temperature environment.

[0018] 3. The condenser tubes are symmetrically arranged on both sides of the first inner tube, forming a dual-path delivery channel. This not only increases the heat exchange area between the cryogenic helium and the liquid helium Dewar and improves the liquefaction efficiency, but also makes the temperature distribution in the condensation chamber more uniform. This avoids the temperature gradient that may be caused by single-path delivery, thereby ensuring that the sample fixture is cooled uniformly and improving the reliability of the ultra-low temperature test data.

[0019] 4. By installing a sealing connector at the upper end of the second outer tube and detachably connecting it to the sealing plate, along with the sealing element in the sealing groove, a reliable seal between the sample chamber and the external environment is achieved. This design facilitates sample loading and replacement, while the rigid connection of the sealing connector ensures the integrity of the overall structure. It is suitable for repeated disassembly and assembly, easy to maintain, and has a long sealing life.

[0020] 5. Since the second section and the adapter assembly of this double-layer sample rod need to be immersed in liquid helium in the liquid helium Dewar during use, conventional rubber O-ring seals are prone to failure at low temperatures. This design adopts an indium-pressed seal method to ensure that it can maintain good sealing performance even in extremely low temperature environments.

[0021] 6. By setting an inlet connector and inlet pipe at the upper end of the first rod section, cryogenic helium can be easily introduced into the condensation layer, realizing controllable input of the refrigerant. This structure facilitates connection with an external gas source system and allows for flexible control of the sample cooling rate by adjusting the inlet flow rate and pressure, enhancing the controllability and repeatability of the entire testing process.

[0022] 7. The design of the lead plate and the clearance groove allows the measurement leads to be rationally arranged on the outside of the first outer tube and inside the sample chamber. The clearance groove avoids interference between the leads and the adapter assembly, which ensures the reliability of electrical signal transmission. In addition, the lower part of the lead connected between the first lead plate and the second lead plate is also immersed in the liquid helium of the liquid helium Dewar, which reduces the conduction of external heat along the lead from top to bottom and helps maintain the extremely low temperature environment of the sample chamber, thereby ensuring measurement accuracy. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural schematic diagram of a double-layer sample rod suitable for ultra-low temperature testing of pulsed magnet liquid helium Dewar provided in an embodiment of this application; Figure 2 yes Figure 1 Enlarged diagram of region E in the middle; Figure 3 This is a top view of a double-layer sample rod suitable for cryogenic testing of pulsed magnet liquid helium Dewar, provided in an embodiment of this application.

[0024] Figure 4 yes Figure 3 A schematic diagram of the AA-direction section; Figure 5 yes Figure 4 Enlarged view of region C in the middle; Figure 6 yes Figure 4 Enlarged schematic diagram of region D in the middle; Figure 7 yes Figure 4 Enlarged schematic diagram of region G in the middle; Figure 8 yes Figure 3 A schematic diagram of the intake connector section in the BB cross-section; Figure 9 This is a schematic diagram of the sealing nozzle in a double-layer sample rod suitable for cryogenic testing of pulsed magnet liquid helium Dewar, provided in an embodiment of this application.

[0025] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 10. First rod segment; 11a. Condensation layer; 11. First outer tube; 12. First inner tube; 12a. Vacuum layer; 12b. Air extraction port; 13. Air inlet connector; 14. Air inlet pipe; 15. First lead plate; 16. Second lead plate; 20. Second rod section; 21. Second outer tube; 22. Second inner tube; 221. Sample clamp; 20a. Sample chamber; 21a. Feed port; 22a. Condensation chamber; 211. Sealing pipe; 211a. Sealing connection platform; 211b. Sealing groove; 30. Adapter assembly; 31. First adapter; 32. Condenser tube; 33. Second adapter; 31a. First adapter cavity; 31b. First upper interface; 31c. First lower interface; 31d. First adapter interface; 33a. Second adapter cavity; 33b. Second lower interface; 33c. Second adapter interface; 31d. Relief groove; 34. Sealing plate. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] like Figure 1 As shown, a double-layer sample rod suitable for cryogenic testing of pulsed magnet liquid helium Dewar includes a first rod segment 10, a second rod segment 20, and an adapter assembly 30.

[0028] Combination Figures 2-8 As shown, the first rod segment 10 includes a first outer tube 11 and a first inner tube 12 coaxially sleeved together. A condensation layer 11a is formed between the first outer tube 11 and the first inner tube 12. The upper end of the first inner tube 12 is provided with an air extraction port 12b and the lower end extends out of the first outer tube 11. A vacuum layer 12a is formed inside the first inner tube 12.

[0029] The second rod segment 20 includes a second outer tube 21 and a second inner tube 22 coaxially sleeved. The upper end of the second outer tube 21 is provided with a feeding port 21a and the lower end is sealed. A sample cavity 20a is formed between the second outer tube 21 and the second inner tube 22. A sample clamp 221 is sealed and installed at the lower end of the second inner tube 22. A condensation cavity 22a is formed inside the second inner tube 22.

[0030] The adapter assembly 30 includes a first adapter 31, a condenser tube 32, a second adapter 33, and a sealing plate 34. The first adapter 31 seals the lower end of the first outer tube 11, and the second adapter 33 seals the upper end of the second inner tube 22. The condenser tube 32 connects the first adapter 31 and the second adapter 33, so that the condensation layer 11a and the condensation chamber 22a are in communication. The sealing plate 34 is fitted on the outside of the first inner tube 12 and is detachably sealed to the feed port 21a.

[0031] The double-layer sample rod of this embodiment is similar to a conventional sample rod in experimental use and needs to be inserted into a cold source. To ensure the smooth use of this application, at least the entire second rod segment 20, the entire adapter assembly 30, and at least a portion of the first rod segment 10 need to be inserted into the liquid helium in the liquid helium Dewar, thereby ensuring that the outer walls of the first outer tube 11, the condenser tube 32, and the second outer tube 21 of the double-layer sample rod are in contact with the liquid helium. The upper end of the condenser layer 11a is used to introduce helium gas, and the upper end of the vacuum layer 12a is used to evacuate the vacuum.

[0032] In this embodiment, a first rod segment 10 having a condensation layer 11a and a vacuum layer 12a and a second rod segment 20 having a sample chamber 20a and a condensation chamber 22a are connected via a transition component 30, combining... Figure 5 and Figure 6 As shown, this allows the flow path of helium gas introduced from the upper end of the condensing layer 11a (condensing layer 11a and condensing tube 32) within the first rod section 10 and the transition assembly 30 section to fully exchange heat with the liquid helium in the external liquid helium Dewar. Thus, when entering the condensing chamber 22a, it can exchange heat with the sample holder 221 in the form of extremely low temperature liquid helium, thereby ensuring that a stable and reliable extremely low temperature environment is created for the sample to be tested. In addition, the sample chamber 20a where the sample to be tested is located outside the condensing chamber 22a and is connected to the vacuum layer 12a. When the vacuum layer 12a is evacuated from the first inner tube 12, a high vacuum environment is simultaneously formed in the sample chamber 20a. The direction of the solid arrow indicates the flow direction of the helium gas introduced from the upper end of the condensing layer 11a, and the direction of the hollow arrow indicates the evacuation direction.

[0033] The first adapter 31 has a first adapter cavity 31a inside, the second adapter 33 has a second adapter cavity 33a inside, and the condenser tube 32 connects the first adapter cavity 31a and the second adapter cavity 33a.

[0034] The first adapter 31 and the second adapter 33 respectively form a first adapter cavity 31a and a second adapter cavity 33a. The design of connecting the first adapter cavity 31a and the second adapter cavity 33a through the condenser tube 32 not only realizes the smooth connection between the condenser layer 11a and the condenser cavity 22a, ensuring the continuity of the helium gas delivery path, but also optimizes the airflow distribution through the buffering and transition function of the adapter cavity, enhancing the overall heat exchange efficiency. At the same time, the compact layout of the adapter helps to reduce unnecessary heat capacity and heat leakage, further improving the stability of the ultra-low temperature environment.

[0035] Specifically, the first adapter 31 has an upper interface 31b at its upper end and a lower interface 31c at its lower end. The first adapter cavity 31a is located between the upper interface 31b and the lower interface 31c. The lower end of the first outer tube 11 is sealed to the upper interface 31b. The lower end of the first inner tube 12 passes through the upper interface 31b and the lower interface 31c in sequence. The outer wall of the first inner tube 12 is sealed to the inner wall of the lower interface 31c. The lower end of the first adapter 31 also has a first adapter interface 31d located on one side of the lower interface 31c.

[0036] The lower end of the second adapter 33 is provided with a second lower end interface 33b that is sealed to the upper end of the second inner tube 22, and the upper end of the second adapter 33 is provided with a second adapter interface 33c that is connected to the condenser tube 32. The second adapter cavity 33a is located between the second lower end interface 33b and the second adapter interface 33c.

[0037] The above design constructs a complete and rigorous helium condensation channel (condensation layer 11a - first transition chamber 31a - condenser tube 32 - second transition chamber 33a), ensuring that helium gas undergoes sufficient heat exchange with liquid helium in the liquid helium Dewar within this condensation channel, condenses into liquid helium, and smoothly enters the condensation chamber 22a. Simultaneously, it strictly isolates the vacuum layer 12a, the condensation channel, and the sample chamber 20a. While achieving a compact structure and reliable sealing, this design significantly improves the long-term operational stability and process repeatability of the entire sample rod under extremely low temperature and vacuum environments.

[0038] In the embodiments of this application, there are two condenser tubes 32, which are symmetrically arranged on both sides of the first inner tube 12. The condenser tubes 32 are rigid metal tubes that penetrate the sealing plate 34 and are fixedly connected to the sealing plate 34.

[0039] Two condenser tubes 32 are symmetrically arranged on both sides of the first inner tube 12, forming a dual-path delivery channel. This not only increases the heat exchange area between the cryogenic helium and the liquid helium Dewar and improves the condensation efficiency, but also makes the temperature distribution in the condensation chamber 22a more uniform, avoiding the temperature gradient that may be caused by single-path delivery and improving the reliability of the data in the ultra-low temperature environment test.

[0040] Among them, the upper end of the second outer tube 21 is fixed with a sealing connector 211, such as Figure 9 As shown, a sealing connection platform 211a is formed at the upper end of the sealing pipe 211. The sealing plate 34 and the sealing connection platform 211a are detachably connected, and the end face of the sealing connection platform 211a is provided with a sealing groove 211b for installing a sealing element.

[0041] By setting a sealing connector 211 near the second outer tube 21 and detachably connecting it to the sealing plate 34, and cooperating with the sealing element in the sealing groove 211b, a reliable seal between the sample chamber 20a and the external environment is achieved. This design facilitates sample loading and replacement. Specifically, when loading the sample to be tested, pulling the first outer tube 11 upward will simultaneously drive the first inner tube 12, the sealing plate 34, and the second inner tube 22 upward until the sample holder 221 is pulled out from the upper end of the second outer tube 21. At the same time, the rigid connection of the sealing connector 211 ensures the integrity of the overall structure, is suitable for multiple disassembly and assembly conditions, is easy to maintain, and has a long sealing life.

[0042] In this embodiment, after the sealing plate 34 is installed on the end face of the sealing connection platform 211a, the sealing plate 34 and the sealing connection platform 211a are locked together by bolts.

[0043] The sealing element is a sealing ring made of pure indium or an indium-based alloy. Since the second rod section 20 and the adapter assembly 30 of the double-layer sample rod in this embodiment need to be immersed in liquid helium in a liquid helium dewar during use, conventional rubber O-ring seals are prone to failure at low temperatures. The sealing element is made of pure indium or an indium-based alloy, forming a pressure-indium seal. Utilizing its characteristic of maintaining good plasticity and sealing performance even at extremely low temperatures, it can tightly adhere to the sealing surface during thermal cycling, effectively preventing vacuum leakage in the sample chamber 20a and ensuring good sealing performance even at extremely low temperatures. Simultaneously, its low thermal conductivity reduces heat leakage along the seal, helping to maintain the low-temperature isolation effect of the sample chamber 20a.

[0044] An air inlet connector 13 is provided at the upper end of the first rod section 10. The first inner tube 12 passes through the air inlet connector 13, and the air inlet connector 13 is connected to an air inlet pipe 14 that communicates with the condensation layer 11a.

[0045] By setting an inlet connector 13 and an inlet pipe 14 at the upper end of the first rod section 10, cryogenic helium can be easily introduced into the condensation layer 11a, realizing the controllable input of the refrigerant. This structure facilitates connection with an external gas source system and allows for flexible control of the sample cooling rate by adjusting the inlet flow rate and pressure during the experiment, enhancing the controllability and repeatability of the entire testing process.

[0046] The air inlet connector 13 and the sealing plate 34 are respectively equipped with a first lead plate 15 and a second lead plate 16. The lead connected between the first lead plate 15 and the second lead plate 16 is located outside the first outer tube 11, and the lead connected to the lower end of the second lead plate 16 is located inside the sample chamber 20a. The outer sides of the first adapter and the second adapter are both formed with clearance grooves 31d for clearance with the lead.

[0047] The design of the lead plate and the clearance groove 31d arranges the measurement leads reasonably on the outside of the first outer tube 11 and inside the sample chamber 20a. The clearance groove 31d avoids interference between the leads and the adapter 30, which ensures the reliability of electrical signal transmission. In addition, the part of the lead connected between the first lead plate 15 and the second lead plate 16 near the lower end is also immersed in the liquid helium of the liquid helium Dewar, which reduces the conduction of external heat along the lead from top to bottom and helps to maintain the extremely low temperature environment of the sample chamber 20a, thereby ensuring measurement accuracy.

[0048] When using the double-layer sample rod of this embodiment, first remove the sealing plate 34, pull the second inner tube 22 out of the second outer tube 21, then fix the sample to be tested on the sample clamp 221, and then insert the second inner tube 22 and tighten the sealing plate 34 again.

[0049] The entire sample rod is inserted into the pulsed field liquid helium Dewar, and the vacuum layer 12a and the entire sample cavity 20a are evacuated through the evacuation port 12b at the upper end of the first rod section 10, thereby establishing and maintaining a high vacuum thermal insulation environment around the sample and effectively isolating external thermal interference.

[0050] Then, cryogenic helium gas is introduced through the inlet pipe 14 at the upper end of the condensation layer 11a. After flowing through the condensation layer 11a and the condenser pipe 32, which are immersed in liquid helium, the helium gas undergoes sufficient heat exchange with the liquid helium in the liquid helium Dewar and condenses and liquefies. The resulting cryogenic liquid helium flows into the condensation chamber 22a and exchanges heat with the sample to be tested through the sample clamp 221, thereby rapidly and stably lowering the sample to the liquid helium temperature range. After the sample temperature stabilizes, the pulsed magnetic field can be activated while maintaining the cooling cycle and vacuum state to perform precise in-situ electrical or magnetic property tests on the sample. After the test, the gas supply and magnetic field are stopped, the sample rod is removed and the vacuum is released, allowing the sample to be disassembled and replaced.

[0051] During the actual test, air was introduced into the inlet pipe 14 at the upper end of the condensation layer 11a. 4 When He gas is introduced, the temperature can be reduced to 1.6K; 3 When using He gas, the temperature can be further reduced to 800 mK, and vacuum layer 12a can pump the gas pressure to 10. - ³ mbar provides a high vacuum environment for the lower sample chamber 20a of the double-layer sample rod.

[0052] The double-layer sample rod of this application is connected to the second rod segment 20 via a transition assembly 30, forming a condensation layer 11a, a vacuum layer 12a, a sample chamber 20a, and a condensation chamber 22a. The refrigerant, after being cooled in the condensation layer 11a, flows into the condensation chamber 22a to directly cool the sample. Simultaneously, the vacuum layer 12a creates a vacuum environment in the sample chamber 20a, ensuring both the achievement of extremely low temperatures and effective controllable thermal isolation between the sample chamber 20a and the external refrigerant, which serves as the cold source.

[0053] It should be understood that expressions such as "comprising" and "may include" as used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0054] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0055] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0056] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0057] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A double-layer sample rod suitable for cryogenic testing in a pulsed magnet liquid helium Dewar, characterized in that, It includes the first segment (10), the second segment (20), and the transition assembly (30). The first rod segment (10) includes a first outer tube (11) and a first inner tube (12) coaxially sleeved together. A condensation layer (11a) is formed between the first outer tube (11) and the first inner tube (12). The upper end of the first inner tube (12) is provided with an air extraction port (12b) and the lower end extends out of the first outer tube (11). A vacuum layer (12a) is formed inside the first inner tube (12). The second rod segment (20) includes a second outer tube (21) and a second inner tube (22) coaxially sleeved. The upper end of the second outer tube (21) is provided with a feeding port (21a) and the lower end is sealed. A sample chamber (20a) is formed between the second outer tube (21) and the second inner tube (22). A sample clamp (221) is sealed and installed at the lower end of the second inner tube (22). A condensation chamber (22a) is formed inside the second inner tube (22). The adapter assembly (30) includes a first adapter (31), a condenser tube (32), a second adapter (33), and a sealing plate (34). The first adapter (31) seals the lower end of the first outer tube (11), and the second adapter (33) seals the upper end of the second inner tube (22). The condenser tube (32) connects the first adapter (31) and the second adapter (33) to communicate with the condensation layer (11a) and the condensation chamber (22a). The sealing plate (34) is fitted on the outside of the first inner tube (12) and is detachably sealed to the feed port (21a).

2. The double-layer sample rod according to claim 1, characterized in that, The first adapter (31) has a first adapter cavity (31a) inside, and the second adapter (33) has a second adapter cavity (33a) inside. The condenser tube (32) connects the first adapter cavity (31a) and the second adapter cavity (33a).

3. The double-layer sample rod according to claim 2, characterized in that, The first adapter (31) has a first upper interface (31b) at its upper end and a first lower interface (31c) at its lower end. The first adapter cavity (31a) is located between the first upper interface (31b) and the first lower interface (31c). The lower end of the first outer tube (11) is sealed to the first upper interface (31b). The lower end of the first inner tube (12) passes through the first upper interface (31b) and the first lower interface (31c) in sequence. The outer wall of the first inner tube (12) is sealed to the inner wall of the first lower interface (31c). The lower end of the first adapter (31) is also provided with a first adapter interface (31d) located on one side of the first lower interface (31c).

4. The double-layer sample rod according to claim 2, characterized in that, The lower end of the second adapter (33) is provided with a second lower end interface (33b) that is sealed and connected to the upper end of the second inner tube (22), and the upper end of the second adapter (33) is provided with a second adapter interface (33c) that is connected to the condenser tube (32). The second adapter cavity (33a) is located between the second lower end interface (33b) and the second adapter interface (33c).

5. The double-layer sample rod according to claim 1, characterized in that, The number of condenser tubes (32) is two and they are symmetrically arranged on both sides of the first inner tube (12).

6. The double-layer sample rod according to claim 1, characterized in that, The condenser tube (32) is a rigid metal tube that penetrates the sealing plate (34) and is fixedly connected to the sealing plate (34).

7. The double-layer sample rod according to claim 1, characterized in that, The upper end of the second outer tube (21) is fixed with a sealing pipe (211), and a sealing connection platform (211a) is formed at the upper end of the sealing pipe (211). The sealing plate (34) and the sealing connection platform (211a) are detachably connected, and the end face of the sealing connection platform (211a) is provided with a sealing groove (211b) for installing a sealing element.

8. The double-layer sample rod according to claim 3, characterized in that, The sealing element is a sealing ring made of pure indium or an indium-based alloy.

9. The double-layer sample rod according to claim 1, characterized in that, An air inlet connector (13) is provided at the upper end of the first rod segment (10), and the first inner tube (12) passes through the air inlet connector (13). The air inlet connector (13) is connected to an air inlet pipe (14) that communicates with the condensation layer (11a).

10. The double-layer sample rod according to claim 9, characterized in that, The air inlet connector (13) and the sealing plate (34) are respectively equipped with a first lead plate (15) and a second lead plate (16). The lead connecting the lower end of the first lead plate (15) and the upper end of the second lead plate (16) is located outside the first outer tube (11), and the lead connecting the lower end of the second lead plate (16) is located in the sample chamber (20a). The outer sides of the first adapter (31) and the second adapter (33) are both formed with clearance grooves (31d) for clearance with the lead.

Images