A superconducting switch and superconducting current lead combined testing device

Abstract

The application relates to the technical field of superconducting magnet system testing, and discloses a superconducting switch and superconducting current lead combined testing device, which comprises a low-temperature system, a superconducting switch, a superconducting current lead and a testing system; the low-temperature system comprises a low-temperature cavity formed by an outer cylinder and a radiation screen, a refrigerator and a heat exchange module, the radiation screen is coaxially arranged in the outer cylinder, the heat exchange module is installed below a primary cold head of the refrigerator, an airflow channel is arranged in the heat exchange module, the superconducting switch is hollow, and the two ends of the superconducting switch are communicated with the airflow channel through circulating pipelines to form a closed gas circulating pipeline; a secondary cold head of the refrigerator is connected with the superconducting switch through a thermal connecting column; a high-temperature end of the superconducting current lead is installed on the heat exchange module, a low-temperature end of the superconducting current lead is connected with the secondary cold head of the refrigerator, and outgoing lines of the low-temperature end are connected with two outgoing lines of the superconducting switch. In the application, the superconducting switch is provided with two-stage heat conduction circuits, so that the cooling efficiency is improved; the superconducting current lead and the superconducting switch can be tested, and the testing efficiency and economy are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of superconducting magnet system testing, in particular to a superconducting switch and superconducting current lead combined testing device. BACKGROUND

[0002] Currently, there are two main cooling methods for superconducting switches in superconducting magnet cryogenic systems: one is a refrigerator conduction cooling method, and the other is a liquid helium immersion cooling method. Generally speaking, the refrigerator conduction cooling method cools the superconducting switch through heat conduction between the refrigerator secondary cold head and the superconducting switch. This method mainly relies on the cooling capacity of the secondary cold head to cool the superconducting switch. For example, in Chinese patent application CN103377788A (Invention title: superconducting magnet system, application publication date: October 30, 2013), the superconducting coil is directly connected to the secondary cold head of the refrigerator through a reversed cold bridge. Due to the small cooling capacity of the secondary cold head at the initial cooling stage, the superconducting switch takes a long time to cool down, reducing the testing efficiency. Moreover, the heat conduction is not uniform, so a large amount of high-thermal-conductivity material is needed to cool the superconducting switch during the heat conduction design, resulting in high testing costs. The liquid helium immersion cooling method cools the superconducting switch by immersing it in liquid helium. This method has high cooling efficiency, but helium is a scarce resource, and the price of liquid helium is particularly high. For batch and long-term testing of superconducting switches, the testing cost is too high, making this method unsuitable.

[0003] Currently, the testing environment for superconducting current leads in superconducting magnet cryogenic systems is usually a 77K liquid nitrogen environment. For testing below 77K, a separate low-temperature testing device needs to be built. In the testing device, a complete test circuit needs to be built for the superconducting current lead, which usually includes room-temperature copper leads and superconducting magnets (or superconducting wires) in addition to the superconducting current lead. Building a separate testing device for testing superconducting current leads has poor economic efficiency.

[0004] Therefore, it is of great commercial value and significance to invent a high-efficiency and cost-effective superconducting switch and superconducting current lead combined testing device. SUMMARY

[0005] To solve the above problems in the prior art, the present application provides a superconducting switch and superconducting current lead combined testing device, which improves the cooling efficiency of the cryogenic system, realizes the combined testing of superconducting current leads and superconducting switches, and improves the testing efficiency and economy.

[0006] To achieve the above technical purposes, the technical solution adopted by the present application is as follows:

[0007] A superconducting switch and superconducting current lead combined testing device, comprising a cryogenic system, a superconducting switch, a superconducting current lead, and a testing system.

[0008] The low-temperature system comprises a low-temperature cavity constructed by an outer cylinder and a radiation screen, a refrigerator, and a heat exchange module, the radiation screen is coaxially arranged in the outer cylinder, the refrigerator is installed on the outer cylinder, a primary cold head and a secondary cold head of the refrigerator are inserted into the inner part of the outer cylinder, the heat exchange module is installed below the primary cold head and extends into the radiation screen, and the top of the heat exchange module is connected with a top plate of the radiation screen;

[0009] The superconducting switch and the superconducting current lead are arranged in the radiation screen; the heat exchange module is provided with an airflow channel, the superconducting switch is hollow, the superconducting switch is connected with the airflow channel of the heat exchange module through a circulating pipeline at both ends, a closed gas circulating pipeline is formed, the gas circulating pipeline is filled with circulating gas, and a primary heat conduction loop is formed; the secondary cold head of the refrigerator is connected with a thermal connection column, the other end of the thermal connection column is connected with the superconducting switch, and a secondary heat conduction loop is formed.

[0010] The superconducting current lead comprises two superconducting current leads, the high-temperature end of the superconducting current lead is installed on the heat exchange module, the high-temperature end is connected with the low-temperature end of a copper lead, and the normal-temperature end of the copper lead extends out of the outer cylinder; the low-temperature end of the superconducting current lead is connected with the secondary cold head of the refrigerator, and the outgoing line of the low-temperature end is connected with two outgoing lines of the superconducting switch.

[0011] The test system comprises an excitation power supply, a monitoring module and a comprehensive test module, the excitation power supply, the monitoring module and the comprehensive test module are electrically connected, the excitation power supply is connected with the normal-temperature end of the copper lead, and the excitation power supply is used for passing current through the superconducting current lead and the superconducting switch; the monitoring module is used for monitoring the temperature, voltage signal and pressure condition in the low-temperature system, and the comprehensive test module is used for recording and displaying the monitoring data and the change trend.

[0012] Further, the heat exchange module comprises a heat exchange plate and a heat exchange block; the heat exchange plate is in an L shape and comprises a heat exchange top plate and a side vertical plate, a circular hole is reserved in the center of the heat exchange top plate, two sets of circumferential holes are arranged on the outer periphery of the circular hole, the inner circumferential hole is used for being connected with the flange of the primary cold head of the refrigerator, and the outer circumferential hole is used for being connected with the top plate of the radiation screen; the heat exchange block is in a strip shape, is connected with the bottom of the heat exchange top plate of the heat exchange plate, is arranged on the side away from the side vertical plate of the heat exchange plate in parallel, a plurality of airflow channels are reserved between the heat exchange block and the heat exchange plate, the airflow channels are connected with stainless steel pipes at both ends, and the stainless steel pipes are connected with the circulating pipeline; a plurality of mounting holes are reserved on the side vertical plate of the heat exchange plate and are used for being connected with the high-temperature end of the superconducting current lead and the low-temperature end of the copper lead.

[0013] Further, the circulating pipeline is provided with a one-way valve, the circulating pipeline is communicated with a gas filling pipeline, the gas filling pipeline passes through the radiation screen and the outer cylinder in sequence, is fixed on the outer cylinder, and the inlet end of the gas filling pipeline is provided with a gas filling port and a pressure monitoring device.

[0014] Further, the one-way valve is a passive one-way valve, the one-way valve comprises a valve body, a flow channel is formed in the valve body, the caliber of the flow channel gradually decreases from an inlet end to an outlet end, the outlet end of the flow channel is provided with a gas baffle, one end of the gas baffle is connected with the outlet end, and the other end is obliquely arranged away from the flow channel, and the projection of the gas baffle on the outlet end of the flow channel is greater than the caliber of the flow channel and smaller than the outer dimension of the valve body.

[0015] Further, the superconducting switch is composed of a framework, a superconducting wire, a baffle and a heater, the framework is a hollow circular tube type, baffles for fixing the superconducting wire are arranged at both ends of the framework, and the superconducting wire is uniformly wound on the framework in a non-inductive winding mode; the heater is a thin resistance heating sheet fixed on the surface of the switch; and an outer extension circular tube is welded at both ends of the framework for connecting a circulating pipeline.

[0016] Further, the thermal connecting column is made of two materials with different thermal conductivities in series, the low-thermal-conductivity section is close to the second cold head end of the refrigerator, and the high-thermal-conductivity section is close to the superconducting switch end.

[0017] Preferably, the low-thermal-conductivity section is made of brass, and the high-thermal-conductivity section is made of oxygen-free copper.

[0018] Further, the superconducting current lead is a high-temperature superconducting current lead, mainly composed of a superconducting tape, a supporting device, an upper copper end head and a lower copper end head, the superconducting tape is connected with the upper copper end head and the lower copper end head at both ends respectively, and the superconducting tape is arranged in the supporting device; the lower copper end head is provided with an interface reserved for welding with a low-temperature superconducting wire, the low-temperature superconducting wire is inserted into and welded in the interface of the lower copper end head to form a low-temperature end outlet of the superconducting current lead; and the upper copper end head is provided with an interface reserved for connecting with a copper lead low-temperature end.

[0019] Further, the low-temperature end of the superconducting current lead is in thermal connection with the second cold head of the refrigerator through a copper bar / copper braid, and the high-temperature end of the superconducting current lead and the low-temperature end of the copper lead are fixedly connected on the side vertical plate of the heat exchange plate; the upper copper end head and the lower copper end head of the superconducting current lead are respectively connected with two test signal lines for monitoring the voltage condition of the superconducting current lead.

[0020] Further, the monitoring module comprises a pressure monitoring submodule, a temperature monitoring submodule, a voltage monitoring submodule and a heating submodule, the pressure monitoring submodule is used for monitoring the pressure in the gas circulating pipeline, the temperature monitoring submodule is used for monitoring the temperature of each key component in the low-temperature system, the voltage monitoring submodule is used for monitoring the voltage signal of the superconducting current lead and the superconducting switch, and the heating submodule is used for heating the superconducting switch.

[0021] The beneficial effects of the application are as follows:

[0022] The superconducting switch and superconducting current lead combined test device of the application, the superconducting switch and the primary cold head of the refrigerator form a primary heat conduction circuit through a gas circulation pipeline, the primary cold head of the refrigerator has large refrigeration capacity, can quickly cool the circulating gas, and can quickly reduce the temperature of the superconducting switch to the temperature of the primary cold head; the superconducting switch and the secondary cold head of the refrigerator form a secondary heat conduction circuit through a thermal connecting column, so that the superconducting switch reaches a lower temperature; under the combined refrigeration of the primary and secondary cold heads of the refrigerator and the high-efficiency circulation of the gas, the cooling efficiency is improved, the amount of heat conduction material used is reduced, and the temperature uniformity of the superconducting switch is improved. In the test device, the superconducting switch is used as a superconducting coil (or superconducting wire), and the two ends thereof form a complete test circuit with the superconducting current lead, so that a combined test device is formed, which can realize the test of the superconducting current lead and the test of the superconducting switch, and the efficiency and economy of the test are improved.

[0023] The superconducting switch and superconducting current lead combined test device of the application, the heat exchange module is connected with the primary cold head of the refrigerator, can provide the refrigeration capacity of the primary cold head for the primary heat conduction circuit, and can provide refrigeration capacity for the high-temperature end of the superconducting current lead and the low-temperature end of the copper lead, the heat exchange plate is in an L shape, and the heat exchange blocks are arranged at intervals between the side vertical plates, so that the heat exchange space can be fully utilized, the heat exchange efficiency of the primary cold head is improved, and the intermediate intercepting temperature is provided for the primary heat conduction circuit and the high-temperature end of the superconducting current lead, so that the heat leakage into the superconducting switch can be reduced, and the stability of the system temperature can be maintained.

[0024] The superconducting switch and superconducting current lead combined test device of the application, the one-way valve arranged in the circulation pipeline enables the circulating gas injected through the gas filling port to circulate in a specific direction in the circulation pipeline, so as to quickly reduce the temperature of the superconducting switch; when the circulating gas is cooled to a low-pressure / low-temperature state, the flow rate of the gas or condensed liquid is slowed down due to the action of the one-way valve, so that the heat conductivity between the primary cold head of the refrigerator and the superconducting switch is inhibited, the minimum temperature of the superconducting switch during cooling is mainly controlled by the secondary cold head of the refrigerator, and under the cooling action of the secondary cold head, the superconducting switch and the low-temperature end of the superconducting current lead can be reduced to a temperature region of about 2.5K.

[0025] The superconducting switch and superconducting current lead combined test device of the application, the thermal connecting column connected between the superconducting switch and the secondary cold head of the refrigerator is made of two materials with different heat conductivities in series, and the heat of the superconducting switch is quickly transferred to the low-heat-conductivity section through the high-heat-conductivity section in the case of heat generation. The rate of heat transfer of the low-heat-conductivity section is reduced, which can effectively slow down or block the heat transfer to the secondary cold head of the refrigerator, so that the superconducting switch does not transfer most of the heat to the secondary cold head of the refrigerator in the case of heat generation, thereby ensuring the overall thermal stability of the system. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor based on the drawings.

[0027] Figure 1 is the principle schematic diagram of the combined test device of the present application;

[0028] Figure 2 is the structural schematic diagram of the low-temperature system;

[0029] Figure 3 is the front view of the heat exchange module;

[0030] Figure 4 is Figure 3 is the sectional view of A-A in FIG. 6;

[0031] Figure 5 is the structural schematic diagram of the one-way valve.

[0032] The drawings are as follows: 1 - superconducting switch, 2 - superconducting current lead, 3 - outer cylinder, 4 - radiation screen, 5 - refrigerator, 501 - primary cold head, 502 - secondary cold head, 6 - heat exchange module, 601 - heat exchange plate, 602 - heat exchange block, 603 - stainless steel pipe, 604 - gas flow channel, 605 - side vertical plate, 7 - circulating pipeline, 8 - gas filling pipeline, 9 - one-way valve, 901 - valve body, 902 - flow channel, 903 - gas baffle, 10 - thermal connection column, 101 - low thermal conductivity section, 102 - high thermal conductivity section, 11 - copper lead, 12 - gas filling port, 13 - pressure monitoring device, 14 - test signal line, 15 - low-temperature superconducting wire, 16 - interface, 17 - excitation power supply, 18 - monitoring module, 19 - comprehensive test module. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, not all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0034] The application relates to a superconducting switch and superconducting current lead combined testing device.

[0035] The low-temperature system comprises a low-temperature cavity constructed by an outer cylinder 3 and a radiation screen 4, a refrigerator 5 and a heat exchange module 6; the radiation screen 4 is coaxially arranged in the outer cylinder 3; the refrigerator 5 is installed on the outer cylinder 3; a primary cold head 501 and a secondary cold head 502 of the refrigerator 5 are inserted into the inner portion of the outer cylinder 3; the heat exchange module 6 is installed below the primary cold head 501 and extends into the radiation screen 4; the top of the heat exchange module 6 is connected with the top plate of the radiation screen 4; the superconducting switch 1 and the superconducting current lead 2 are arranged in the radiation screen 4; an airflow channel 604 is arranged in the heat exchange module 6; the superconducting switch 1 is hollow; the two ends of the superconducting switch 1 are communicated with the airflow channel 604 of the heat exchange module 6 through a circulating pipeline 7 to form a closed gas circulating pipeline; the gas circulating pipeline is filled with circulating gas to form a primary heat conduction loop and provide the superconducting switch 1 with refrigerating capacity from the primary cold head 501 of the refrigerator; the secondary cold head 502 of the refrigerator is connected with a thermal connecting column 10; the other end of the thermal connecting column 10 is connected with the superconducting switch 1 to form a secondary heat conduction loop and provide the superconducting switch 1 with refrigerating capacity from the secondary cold head 502 of the refrigerator and provide the superconducting switch 1 with lower temperature; the superconducting current lead 2 comprises two superconducting current leads; the high-temperature end of the superconducting current lead 2 is installed on the heat exchange module 6; the high-temperature end is connected with the low-temperature end of a copper lead 11; the normal-temperature end of the copper lead 11 extends out of the outer cylinder 3; the low-temperature end of the superconducting current lead 2 is connected with the secondary cold head 502 of the refrigerator; the outgoing line of the low-temperature end is connected with two outgoing lines of the superconducting switch 1.

[0036] The testing system comprises an excitation power supply 17, a monitoring module 18 and a comprehensive testing module 19; the excitation power supply 17, the monitoring module 18 and the comprehensive testing module 19 are electrically connected; the excitation power supply 17 is connected with the high-temperature end of the copper lead 11 and is used for passing current through the superconducting current lead 2 and the superconducting switch 1; the monitoring module 18 is used for monitoring the temperature, voltage signal and pressure condition in the low-temperature system.

[0037] Specifically, the outer cylinder 3 is a circular cavity and mainly comprises a top flange, a circumferential cylinder and a circular bottom plate; the outer cylinder 3 can be made of stainless steel; the outer cylinder 3 can isolate the inner portion of the outer cylinder 3 from the room temperature environment and provide a high-vacuum environment in the inner portion; the top flange of the outer cylinder 3 is provided with a reserved interface 16 for installing the refrigerator 5, the copper lead 11, a gas filling pipeline 8, a testing signal line 14 and other related testing devices.

[0038] The radiation screen 4 is a circular cylinder coaxially arranged with the outer cylinder 3, mainly composed of a top plate, a circumferential cylinder and a bottom plate, and made of aluminum alloy or copper with high thermal conductivity. The radiation screen 4 is mainly used for shielding thermal radiation from room temperature and reducing radiation heat leakage of the system. The top plate of the radiation screen 4 is provided with a reserved hole for facilitating the refrigeration machine cold head or the related test device to enter the low-temperature environment from the room temperature. The top plate of the radiation screen 4 is provided with a reserved threaded hole for connecting with the top of the heat exchange module 6. The inner cylinder space of the radiation screen 4 is the test environment of the superconducting switch 1 and the superconducting current lead 2.

[0039] The refrigeration machine 5 is a GM refrigeration machine. The room temperature flange of the refrigeration machine 5 is connected with the top flange of the outer cylinder 3. The first-level cold head 501 and the second-level cold head 502 of the refrigeration machine are inserted into the inner part of the outer cylinder 3. The heat exchange module 6 is installed below the first-level cold head 501. The heat exchange module 6 is used for installing the radiation screen 4, the superconducting current lead 2 and the circulating pipeline 7, and providing the cold quantity from the first-level cold head 501 for them.

[0040] The heat exchange module 6 includes a heat exchange plate 601 and a heat exchange block 602. The heat exchange plate 601 is an L-shaped copper plate, including a heat exchange top plate and a side vertical plate 605. A circular hole is reserved in the center of the heat exchange top plate for facilitating the second-level cold head 502 of the refrigeration machine to pass through. Two sets of circumferential holes are arranged on the outer periphery of the circular hole. The inner circumferential hole is used for connecting with the flange of the first-level cold head 501 of the refrigeration machine for positioning the heat exchange module 6. The outer circumferential hole is used for connecting with the threaded hole of the top plate of the radiation screen 4 for positioning the radiation screen 4 and simultaneously transferring the cold quantity from the first-level cold head 501 of the refrigeration machine. The heat exchange block 602 is in a long strip shape, connected at the bottom of the heat exchange top plate of the heat exchange plate 601, and arranged in parallel on one side away from the side vertical plate 605 of the heat exchange plate 601. A plurality of air flow channels 604 are reserved between the heat exchange block 602 and the heat exchange plate 601. The two ends of the air flow channel 604 are connected with stainless steel pipes 603. The stainless steel pipes 603 are connected with the circulating pipeline 7. The superconducting switch 1 is connected with the air flow channel 604 through the circulating pipeline 7 to form a closed gas circulating pipeline, i.e. a first-level heat conduction loop. The gas injected through the gas filling pipeline 8 circulates in the circulating pipeline 7 in a specific direction. The gas fully exchanges heat with the heat exchange plate 601 in the air flow channel 604 to provide the superconducting switch 1 with the refrigeration quantity from the first-level cold head 501 of the refrigeration machine, so as to achieve the purpose of rapidly reducing the temperature of the superconducting switch 1. The heat exchange block 602 and the heat exchange plate 601 can be connected together by welding to ensure the heat conductivity therebetween. A plurality of mounting holes are reserved on the side vertical plate 605 of the heat exchange plate 601 for connecting the high-temperature end of the superconducting current lead 2 and the low-temperature end of the copper lead 11, so as to cool the superconducting current lead 2 and provide an intermediate current interruption temperature for the superconducting current lead 2 to reduce the heat leakage into the superconducting switch 1.

[0041] The circulating pipeline 7 is made of stainless steel pipe and is located inside the radiation screen 4. The circulating pipeline 7 is connected with the stainless steel pipe 603 of the heat exchange module 6 and both sides of the superconducting switch 1 to form a closed gas circulating pipeline. The circulating pipeline 7 is connected with the gas filling pipeline 8. The gas filling pipeline 8 passes through the radiation screen 4 and the outer cylinder 3 in sequence and is fixed on the top flange of the outer cylinder 3. The gas filling pipeline 8 is provided with a gas filling port 12 and a pressure monitoring device 13 at the inlet end of the gas filling pipeline 8 outside the outer cylinder 3. The circulating gas injected into the circulating pipeline 7 through the gas filling port 12 can circulate in the circulating pipeline 7 to achieve the purpose of rapidly reducing the temperature of the superconducting switch 1. The circulating gas is generally high-pressure gas. The circulating gas exists in the form of solid or liquid at a temperature below 30K, such as nitrogen, argon, helium and the like. The pressure monitoring device 13 is mainly used for monitoring the pressure during the whole experiment to ensure the safety and reliability of the experiment.

[0042] The one-way valve 9 is installed in the circulating pipeline 7. The one-way valve 9 is a passive one-way valve. The one-way valve 9 comprises a valve body 901. A flow channel 902 is formed in the valve body 901. The diameter of the flow channel 902 gradually decreases from the inlet end to the outlet end. The outlet end of the flow channel 902 is provided with a gas baffle 903. One end of the gas baffle 903 is connected with the outlet end. The other end of the gas baffle 903 is inclined to be away from the flow channel 902. The projection of the gas baffle 903 on the outlet end of the flow channel 902 is greater than the diameter of the flow channel 902 and smaller than the outer size of the valve body 901. The one-way valve 9 enables the circulating gas to flow in a specific direction while increasing the flow resistance of the gas. When the gas is in a high-temperature / high-pressure state, the circulating speed of the gas in the circulating pipeline 7 is relatively fast, so that the superconducting switch 1 can be rapidly cooled. When the gas is cooled to a low-pressure / low-temperature state, the flow rate of the gas or the condensed liquid is slowed down due to the action of the one-way valve 9, so that the thermal conductivity between the primary cold head 501 of the refrigerator and the superconducting switch 1 is inhibited. The minimum temperature of the superconducting switch 1 is mainly controlled by the secondary cold head 502 of the refrigerator.

[0043] The superconducting switch 1 mainly comprises a framework, a superconducting wire, a baffle and a heater. The framework is a hollow circular pipe made of oxygen-free copper. The framework is provided with baffles at both ends for fixing the superconducting wire. The superconducting wire is uniformly wound on the framework in a non-inductive way. The heater is a thin resistance heating sheet fixed on the surface of the switch for heating the switch. The framework is welded with an outer extension pipe at both ends. The outer extension pipe can be made of stainless steel pipe and is used for connecting the circulating pipeline 7 to form a closed gas circulating loop. One side of the framework is provided with a plane connected with the thermal connecting column 10. The superconducting switch 1 can form a secondary heat conduction loop with the secondary cold head 502 of the refrigerator through the plane connecting the thermal connecting column 10 to achieve a lower cooling temperature.

[0044] Preferably, the thermal connecting column 10 connected with the second-stage cold head 502 of the refrigerator and the superconducting switch 1 is made of two materials with different thermal conductivities in series, the low-thermal-conductivity section 101 is close to the second-stage cold head 502 of the refrigerator, and the high-thermal-conductivity section 102 is close to the superconducting switch 1. Preferably, the low-thermal-conductivity section 101 is made of brass, and the high-thermal-conductivity section 102 is made of oxygen-free copper. In the case of heat generation of the superconducting switch 1, the heat is rapidly transferred to the low-thermal-conductivity section 101 through the high-thermal-conductivity section 102, and the heat transfer rate of the low-thermal-conductivity section 101 is reduced, so that the heat transfer to the second-stage cold head 502 of the refrigerator is slowed down or interrupted, thereby ensuring the overall thermal stability of the system.

[0045] The superconducting current lead 2 is a high-temperature superconducting current lead mainly composed of a superconducting tape, a supporting device, an upper copper end head, and a lower copper end head. The superconducting tape is connected with the upper copper end head and the lower copper end head at both ends, respectively, and is installed in the supporting device. The superconducting current lead 2 has a high-temperature end close to the first-stage cold head 501 of the refrigerator and a low-temperature end close to the second-stage cold head 502 of the refrigerator. The low-temperature end of the superconducting current lead 2 is thermally connected with the second-stage cold head 502 of the refrigerator through a copper bar / copper braid (not shown in the figure). The high-temperature end of the superconducting current lead 2 and the low-temperature end of the copper lead 11 are fixed on the side vertical plate 605 of the heat exchange plate 601. In normal operation, the high-temperature end of the superconducting current lead 2 is in a temperature range of 30-50K, and the low-temperature end is in a temperature range of about 2.5K-4.2K, which provides a good low-temperature environment for the superconducting state. In particular, the low-temperature end and the high-temperature end of the superconducting current lead 2 need to be well insulated at the thermal connection with the first-stage cold head 501 and the second-stage cold head 502 of the refrigerator. Insulating materials such as Mylar insulation film or aluminum nitride insulation sheet can be added at the thermal connection. In order to realize the test of the superconducting current lead 2, the upper copper end head and the lower copper end head of the superconducting current lead 2 are respectively connected with two test signal lines 14 for monitoring the voltage condition of the superconducting current lead 2.

[0046] Specifically, the lower copper end of the superconducting current lead 2 is pre-wired for welding with a low-temperature superconducting wire 15. The low-temperature superconducting wire 15 is inserted and welded into this lower copper end, forming the outlet of the superconducting current lead 2 at the low-temperature end. This outlet facilitates connection to the outlet of the superconducting switch 1. Specifically, the outlet of the superconducting switch 1 and the outlet of the superconducting current lead 2 at the low-temperature end are connected using a lap joint. This lap joint is first wrapped with tinned copper wire and then welded. The lap length is minimized to greater than 60 mm to minimize weld resistance. The high-temperature end of the superconducting current lead 2 is pre-wired for connection with the low-temperature end of the copper lead 11. Both are secured to the side riser 605 of the heat exchange plate 601. This connection establishes an electrical connection while receiving cooling from the first-stage cold head 501 of the refrigerator, providing an intermediate cutoff temperature for the low-temperature end of the copper lead 11 and reducing heat leakage. The room-temperature end of the copper lead 11 is secured to the flange of the outer cylinder 3. In terms of circuit testing, the two output lines of the superconducting switch 1 are respectively connected to the output lines of the two low-temperature ends of the superconducting current lead 2, the high-temperature end of the superconducting current lead 2 is connected to the low-temperature end of the copper lead 11, and the copper lead 11 is then connected to the external excitation power supply 17. A complete circuit test loop is formed in a layer-by-layer progressive manner, which can be used for current-carrying testing of the superconducting switch 1 and the superconducting current lead 2.

[0047] Furthermore, the cryogenic system and the test system are connected via a signal line interface 16 and a copper lead 11, as shown in the attached diagram. Figure 2 As shown. Monitoring module 18 includes a pressure monitoring submodule, a temperature monitoring submodule, a voltage monitoring submodule, and a heating submodule. The pressure monitoring submodule is communicatively connected to pressure monitoring device 13 and is used to monitor the pressure within the gas circulation pipeline. The temperature monitoring submodule is used to monitor the temperature of key components in the cryogenic system. The voltage monitoring submodule is connected to test signal line 14 to monitor the voltage signal of superconducting current lead 2 and superconducting switch 1. The heating submodule is connected to a heater and is used to heat superconducting switch 1 to test its recovery from superconducting state and normal state. The data monitored by monitoring module 18 is integrated into comprehensive test module 19 via a communication interface, allowing real-time viewing of relevant data and changing trends.

[0048] After completing the connection and cooling of the above-mentioned devices, the cooling and current-carrying performance tests of the superconducting switch 1 and the superconducting current lead 2 can be carried out. The entire experimental process is as follows: First, high-pressure gas (for example, nitrogen, argon, or helium) is filled into the circulation pipeline 7 through the gas filling port 12. After the pressure reaches the target value, the gas filling port 12 is closed, and the refrigerator 5 is started to start cooling the superconducting switch 1 and the superconducting current lead 2.

[0049] The superconducting switch 1 is cooled by the primary cold head 501 and the secondary cold head 502 of the refrigerator, and the high-temperature end of the superconducting current lead 2 is cooled by the primary cold head 501 of the refrigerator, and the low-temperature end is cooled by the secondary cold head 502 of the refrigerator. In the initial stage of the cooling process, the primary cold head 501 of the refrigerator has a large amount of cold, and can quickly cool the circulating gas, and the superconducting switch 1 is quickly reduced to the temperature of the primary cold head 501 through the gas circulation. When the temperature of the superconducting switch 1 is lower than the temperature of the primary cold head 501, at this time, the gas in the circulating pipeline 7 is condensed due to the action of gravity and the one-way valve 9, and the condensed liquid or solid is deposited at the bottom of the gas circulation pipeline 7 (at the skeleton of the superconducting switch 1), which greatly reduces the thermal connection between the superconducting switch 1 and the primary cold head 501. Under the cooling action of the secondary cold head 502, the low-temperature end of the superconducting switch 1 and the superconducting current lead 2 can be reduced to a temperature region of about 2.5K.

[0050] After being reduced to the target temperature, the superconducting switch 1 and the superconducting current lead 2 are subjected to current-carrying test by the external excitation power supply 17, and the temperature and voltage signals are monitored in real time during the experiment, and the performance of the superconducting switch 1 and the superconducting current lead 2 is judged by the quench temperature and the quench voltage, so as to achieve the test purpose.

[0051] The superconducting switch 1 and the superconducting current lead 2 are innovatively designed, and the heat exchange module 6, the circulating pipeline 7 and the one-way valve 9 are innovatively introduced, so that the combined cooling and current-carrying test of the superconducting switch 1 and the superconducting current lead 2 can be efficiently and quickly realized, and multiple beneficial effects can be achieved in system test. On the one hand, the system heat leakage is greatly reduced, and compared with the liquid helium immersion cooling, the test temperature region is lower, and the lowest can reach about 2.5K, and the reliability of the test is improved. On the other hand, the system cooling performance is excellent, not only the cooling efficiency is improved, but also the temperature uniformity is improved. According to the comparison of the related test results, compared with the conduction cooling mode of the refrigerator, the overall temperature uniformity of the superconducting switch 1 can be maintained within 0.2K, and the system cooling efficiency is improved by at least 30%.

[0052] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications should belong to the protection scope of the claims attached to the present application.

Claims

1. A combined testing device for superconducting switches and superconducting current leads, characterized in that: The low-temperature system, the superconducting switch, the superconducting current lead, and the test system are provided. The low-temperature system comprises a low-temperature cavity constructed by an outer cylinder and a radiation screen, a refrigerator, and a heat exchange module. The superconducting switch and the superconducting current lead are arranged in the radiation screen. The heat exchange module is internally provided with an airflow channel, and the superconducting switch is hollow. The two ends of the superconducting switch are connected with the airflow channel of the heat exchange module through a circulating pipeline to form a closed gas circulating pipeline.

2. The combined superconducting switch and superconducting current lead test device of claim 1, wherein: The gas circulating pipeline is filled with circulating gas to form a primary heat conduction loop.

3. The combined superconducting switch and superconducting current lead test device of claim 1, wherein: The second cold head of the refrigerator is connected with a thermal connecting column, and the other end of the thermal connecting column is connected with the superconducting switch to form a secondary heat conduction loop.

4. The combined superconducting switch and superconducting current lead test device of claim 3, wherein: The heat exchange module comprises a heat exchange plate and a heat exchange block. The heat exchange plate is connected with the first cold head of the refrigerator and the top plate of the radiation screen. The heat exchange block is connected at the bottom of the heat exchange plate. The heat exchange block and the heat exchange plate are provided with a plurality of airflow channels. The two ends of the airflow channels are connected with stainless steel pipes, and the stainless steel pipes are connected with the circulating pipeline. The superconducting current lead comprises two superconducting current leads. The high-temperature end of the superconducting current lead is arranged on the heat exchange module. The high-temperature end of the superconducting current lead is connected with the low-temperature end of a copper lead. The normal-temperature end of the copper lead extends out of the outer cylinder. The low-temperature end of the superconducting current lead is connected with the second cold head of the refrigerator. The two outgoing lines of the low-temperature end are connected with two outgoing lines of the superconducting switch. The test system comprises an excitation power supply, a monitoring module, and a comprehensive test module. The excitation power supply, the monitoring module, and the comprehensive test module are electrically connected. The excitation power supply is connected with the normal-temperature end of the copper lead. The excitation power supply is used for passing current through the superconducting current lead and the superconducting switch. The monitoring module is used for monitoring the temperature, voltage signal, and pressure in the low-temperature system. The comprehensive test module is used for recording and displaying the monitoring data and the change trend. The heat exchange plate is in an L shape and comprises a heat exchange top plate and a side vertical plate. A circular hole is provided in the center of the heat exchange top plate. Two sets of circular holes are provided on the outer periphery of the circular hole. The inner circular hole is used for connecting with the flange of the first cold head of the refrigerator. The outer circular hole is used for connecting with the top plate of the radiation screen. The heat exchange block is in a strip shape and is connected at the bottom of the heat exchange top plate of the heat exchange plate. The heat exchange block is parallel arranged on the side away from the side vertical plate of the heat exchange plate. A plurality of mounting holes are provided on the side vertical plate of the heat exchange plate. The mounting holes are used for connecting the high-temperature end of the superconducting current lead and the low-temperature end of the copper lead. The circulating pipeline is provided with a one-way valve. The circulating pipeline is connected with a gas filling pipeline. The gas filling pipeline passes through the radiation screen and the outer cylinder in sequence and is fixed on the outer cylinder. A gas filling port and a pressure monitoring device are provided at the inlet end of the gas filling pipeline. The one-way valve is a passive one-way valve. The one-way valve comprises a valve body. A flow channel is provided in the valve body. The diameter of the flow channel gradually decreases from the inlet end to the outlet end. The outlet end of the flow channel is provided with a gas baffle. One end of the gas baffle is connected with the outlet end. The other end of the gas baffle is inclinedly arranged away from the flow channel. The projection of the gas baffle on the outlet end of the flow channel is greater than the diameter of the flow channel and smaller than the outer size of the valve body.

5. The combined superconducting switch and superconducting current lead test device of claim 1, wherein: The superconducting switch is composed of a framework, superconducting wires, baffles and a heater, the framework is a hollow circular tube, baffles for fixing the superconducting wires are installed at both ends of the framework, the superconducting wires are uniformly wound on the framework in a non-inductive winding manner; the heater is a thin sheet resistance heating sheet fixed on the surface of the switch; an outer extension pipe is welded at both ends of the framework for connecting a circulating pipeline.

6. The combined superconducting switch and superconducting current lead test device of claim 1, wherein: The heat connecting column is made of two materials with different thermal conductivities in series, the low-thermal-conductivity section is close to the secondary cold head end of the refrigerator, and the high-thermal-conductivity section is close to the superconducting switch end.

7. The combined superconducting switch and superconducting current lead test device of claim 6, wherein: The low-thermal-conductivity section is made of brass, and the high-thermal-conductivity section is made of oxygen-free copper.

8. The combined superconducting switch and superconducting current lead test device of claim 2, wherein: The superconducting current lead is a high-temperature superconducting current lead mainly composed of superconducting tapes, a supporting device, an upper copper end head and a lower copper end head, the superconducting tapes are connected to the upper copper end head and the lower copper end head at both ends respectively, and the superconducting tapes are installed inside the supporting device; the lower copper end head is provided with an interface for welding with a low-temperature superconducting wire, the low-temperature superconducting wire is inserted into and welded in the interface of the lower copper end head to form a low-temperature end outlet of the superconducting current lead; the upper copper end head is provided with an interface for connecting with a copper lead low-temperature end.

9. The combined superconducting switch and superconducting current lead test device of claim 8, wherein: The low-temperature end of the superconducting current lead is connected to the secondary cold head of the refrigerator through a copper bar / copper braid, the high-temperature end of the superconducting current lead and the low-temperature end of the copper lead are fixedly connected to the side vertical plates of the heat exchange plate; the upper copper end head and the lower copper end head of the superconducting current lead are respectively connected with two test signal lines for monitoring the voltage condition of the superconducting current lead.

10. The combined superconducting switch and superconducting current lead test device of claim 1, wherein: The monitoring module includes a pressure monitoring submodule, a temperature monitoring submodule, a voltage monitoring submodule and a heating submodule, the pressure monitoring submodule is used for monitoring the pressure in the gas circulating pipeline, the temperature monitoring submodule is used for monitoring the temperature of each key component in the low-temperature system, the voltage monitoring submodule is used for monitoring the voltage signal of the superconducting current lead and the superconducting switch, and the heating submodule is used for heating the superconducting switch.

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