Superconducting wire critical current testing device and testing method

Abstract

The present invention belongs to the technical field of superconducting wire testing, and discloses a superconducting wire critical current testing device, comprising a superconducting magnet that provides a background magnetic field, wherein a superconducting wire sample testing thermostat is internally connected to the superconducting magnet that provides the background magnetic field, a sample rod is provided through the top center of the superconducting wire sample testing thermostat, and the sample rod passes through the superconducting wire sample testing thermostat and is provided at the center of the superconducting magnet that provides the background magnetic field. The superconducting wire critical current testing device provided by the present invention has a more reasonable structure for performance testing of low-temperature superconducting wires at 4.2K, enhanced reliability, and greater convenience of use. The superconducting wire critical current testing method provided by the present invention effectively improves the efficiency of the test and significantly reduces the consumption of liquid helium during the sample testing process.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting wire testing, in particular to a superconducting wire critical current testing device and a testing method. Background Art

[0002] Currently, the most widely used superconducting material is low-temperature superconducting wire, which is widely used in magnetic resonance imaging (MRI), nuclear magnetic resonance spectrometer (NMR), magnetron Czochralski single crystal silicon equipment (MCZ), particle accelerators, superconducting energy storage systems (SMES), magnetic confinement nuclear fusion devices (Tokamak) and other fields.

[0003] Prior art testing of critical current of low-temperature superconducting wires requires performance testing in liquid helium. Currently, a cryogenic dewar with a background field superconducting coil is used. Both the background field superconducting coil and the sample are immersed in liquid helium. Cooling the superconducting magnet consumes a large amount of liquid helium, and liquid helium is used to maintain the superconducting state during testing. Liquid helium is a global strategic resource. In recent years, due to various factors, the global helium supply has experienced an unprecedented shortage, and the price of liquid helium has doubled. This results in high liquid helium usage in prior art and high production costs for companies. Furthermore, direct cooling of superconducting wire samples for performance testing is inefficient and unsuitable for batch superconducting wire performance testing. Summary of the Invention

[0004] The present invention aims to provide a superconducting wire critical current testing device and method, which provides an adjustable background magnetic field, significantly reduces the amount of liquid helium used in superconducting wire testing, and rapidly obtains performance data. This addresses the aforementioned issues raised in the background art, such as the high amount of liquid helium used in the prior art, resulting in high production costs for enterprises. Furthermore, the performance testing method using direct cooling of superconducting wire samples is inefficient and unsuitable for batch superconducting wire performance testing.

[0005] To achieve the above object, the present invention provides the following technical solution:

[0006] A superconducting wire critical current testing device includes a superconducting magnet that provides a background magnetic field, a superconducting wire sample testing thermostat connected to the superconducting magnet that provides the background magnetic field, a sample rod penetrating the center of the top of the superconducting wire sample testing thermostat, and the sample rod penetrating the superconducting wire sample testing thermostat is arranged at the center of the superconducting magnet that provides the background magnetic field;

[0007] The superconducting magnet providing the background magnetic field includes a superconducting coil, a superconducting magnet cryostat, a refrigerator for the superconducting magnet, a room temperature hole, and a copper braided flexible connection. The room temperature hole is provided at the center of the superconducting magnet providing the background magnetic field, a superconducting coil is provided outside the room temperature hole, a superconducting magnet cryostat is provided outside the superconducting coil, and one side of the superconducting coil is further connected to the refrigerator for the superconducting magnet via a copper braided flexible connection.

[0008] The superconducting wire sample testing thermostat comprises a helium tank, a radiation shield, an outer vacuum layer, a refrigerator for the sample testing thermostat, a superconducting wire sample area, a liquid helium storage area, a liquid helium level gauge, a condenser, a nitrogen tank, a sample rod inlet, a safety valve, a second cold shield, and a radiation plate. The superconducting wire sample testing thermostat is provided at the connection between the superconducting wire sample testing thermostat and the room temperature hole of the superconducting magnet providing the background magnetic field. The superconducting wire sample area is provided outside the superconducting wire sample area. The liquid helium storage area and the liquid helium level gauge are provided inside the helium tank. The radiation shield is provided outside the helium tank. The radiation plate is provided at the center of the radiation shield. The outer vacuum layer is provided outside the radiation shield. The sample rod inlet is provided at the center of the end of the superconducting wire sample testing thermostat. The sample rod inlet is sleeved with a sample rod.

[0009] When a refrigerator for a sample test thermostat is provided inside the superconducting wire sample test thermostat, the top of the sample test thermostat is connected to the refrigerator for the sample test thermostat, and the refrigerator for the sample test thermostat includes a condenser, which is connected to the cold head end of the refrigerator for the sample test thermostat. The top of the refrigerator for the sample test thermostat is connected to a refrigerator base, which passes through the end of the superconducting wire sample test thermostat and is fixedly connected to the end of the superconducting wire sample test thermostat. A pressure sensor is provided on one side of the sample rod inlet, and a safety valve is provided on the end surface of the superconducting wire sample test thermostat on the other side of the sample rod inlet. The superconducting wire sample test thermostat is also electrically connected to a pressure control unit.

[0010] When a refrigerator for a sample test thermostat is not provided inside the superconducting wire sample test thermostat, a nitrogen tank is provided between the radiation screen and the outer vacuum layer, a safety valve is provided on the side of the sample rod inlet, and a liquid nitrogen infusion port is also provided on the top of the nitrogen tank.

[0011] Further preferably, the pressure control unit further includes a heater and a pressure controller, the heater is arranged inside the helium tank, and the pressure sensor is electrically connected to the pressure controller.

[0012] Further preferably, the helium tank includes a superconducting wire sample area helium tank, a liquid helium storage area helium tank and a sample cavity, the superconducting wire sample area helium tank is arranged inside the superconducting wire sample area, and the liquid helium storage area helium tank is arranged inside the liquid helium storage area.

[0013] Further preferably, a superconducting wire sample is provided at one end of the sample rod close to the helium tank of the superconducting wire sample area.

[0014] Further preferably, the superconducting coil includes a niobium-titanium superconducting coil, a niobium-tin superconducting coil and a high-temperature superconducting coil, and the outside of the room-temperature hole is sequentially provided with a high-temperature superconducting coil, a niobium-tin superconducting coil and a niobium-titanium superconducting coil from the inside to the outside, and thermometer probes are respectively provided on the upper and lower sides of the superconducting coil.

[0015] Further preferably, the superconducting magnet cryostat includes a first cold shield, a high-temperature superconducting current lead and a vacuum layer, the first cold shield is provided on the outside of the superconducting coil, the vacuum layer is provided on the outside of the first cold shield, and one side of the first cold shield is connected to a refrigerator for the superconducting magnet.

[0016] Further preferably, the refrigerator for the superconducting magnet includes a primary cold head and a secondary cold head, the primary cold head is connected to the first cold screen, the secondary cold head is connected to the superconducting coil through a copper braided flexible connection, and the positive and negative leads of the superconducting magnet providing the background magnetic field are also electrically connected to the superconducting coil through high-temperature superconducting current leads.

[0017] The present invention also provides a technical solution:

[0018] A method for testing a superconducting wire critical current test device comprises the following steps:

[0019] S100, cooling down a superconducting magnet providing a background magnetic field and measuring its magnetic properties;

[0020] S110, cooling the superconducting wire sample test thermostat;

[0021] S120, exciting a superconducting magnet that provides a background magnetic field;

[0022] S130, installing a sample rod, and placing the sample rod containing the superconducting wire sample into a superconducting wire sample test thermostat;

[0023] S140, adjusting the magnetic field strength of the superconducting magnet providing the background magnetic field;

[0024] S150, conducting a power-on test on the superconducting wire sample;

[0025] S160, re-adjusting the magnetic field strength of the superconducting magnet providing the background magnetic field, and removing the superconducting wire sample after the power-on test;

[0026] S170. After the test is completed, the superconducting magnet providing the background magnetic field is demagnetized.

[0027] Further preferably, when cooling the superconducting wire sample test thermostat, the superconducting wire sample test thermostat is cooled by a sample test thermostat refrigerator or by liquid nitrogen;

[0028] When cooling the superconducting wire sample test thermostat with liquid nitrogen, first use liquid nitrogen to cool the helium tank of the superconducting wire sample test thermostat. After the helium tank is soaked in liquid nitrogen for at least half an hour, the liquid nitrogen is removed and the helium tank is replaced and cleaned with helium for at least three times. Then, liquid nitrogen is filled into the nitrogen tank. After the liquid nitrogen is full, liquid helium is started to be filled into the helium tank for cooling. The liquid helium level in the helium tank is observed with a liquid helium level gauge. When the liquid helium level reaches the designed target value, the helium infusion is stopped and the infusion line is unplugged.

[0029] When the superconducting wire sample test thermostat is cooled by a refrigerator through the sample test thermostat, liquid nitrogen is first used to cool the helium tank of the superconducting wire sample test thermostat. The liquid nitrogen is removed after the helium tank is soaked in liquid nitrogen for no less than half an hour, and the helium tank is replaced and cleaned with helium for no less than three times. After the inlet of the sample rod is sealed, the helium tank is kept in a slightly positive pressure state. The sample test thermostat is opened and the refrigerator is used to cool the radiation screen of the superconducting wire sample test thermostat. After the temperature at the far end of the radiation screen is lower than 60K, liquid helium is started to be filled into the helium tank for cooling. The liquid helium level in the helium tank is observed using a liquid helium level gauge. After reaching the design target value, the helium infusion is stopped and the infusion line is unplugged. After the pressure value of the pressure control unit is set to 1-3KPa through the pressure controller, the heater in the helium tank starts to work. At this time, the pressure in the helium tank is stabilized at 1-3KPa, and the superconducting wire sample test thermostat maintains a zero-volatility state of liquid helium.

[0030] Further preferably, the magnetic field strength of the superconducting magnet providing the background magnetic field is not less than 10 Tesla.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The entire device uses a refrigerator to directly cool the superconducting magnet, which provides the background magnetic field. The superconducting wire sample testing thermostat is a liquid helium low-volatility or micro-volatility thermostat. This micro-volatility or micro-volatility superconducting wire sample testing thermostat is inserted into the magnet's room-temperature hole. Compared to previous designs where both the background field superconducting coil and the sample are immersed in liquid helium, this separate structure reduces the storage and usage of liquid helium for the initial cooling of the entire device. This also reduces the amount of liquid helium used during superconducting wire sample testing and reduces liquid helium loss caused by occasional quenching of the background field superconducting coil. The use of an independent superconducting wire sample testing thermostat improves the efficiency of superconducting wire sample testing and effectively prevents the formation of solids at the bottom of the coil and in the center hole after multiple tests. The micro-volatility or micro-volatility superconducting wire sample testing thermostat suppresses the volatilization of liquid helium in the sample cavity during testing breaks or during nighttime shutdown, maintaining a low or micro-volatility level.

[0033] In summary, the superconducting wire critical current testing device provided by the present invention has a more rational structure, enhanced reliability, and greater ease of use for testing the performance of low-temperature superconducting wires at 4.2K. The superconducting wire critical current testing method provided by the present invention effectively improves testing efficiency and significantly reduces liquid helium consumption during sample testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the overall structure of Example 1 of the present invention;

[0035] Figure 2 This is a cross-sectional view of the overall structure of Example 1 of the present invention;

[0036] Figure 3 This is a cross-sectional view of the overall structure of Example 2 of the present invention;

[0037] Figure 4 is a flow chart of the testing method of the present invention;

[0038] Figure 5 This is a flow chart of the testing method of Example 1 of the present invention;

[0039] Figure 6 This is a flow chart of the testing method of Example 2 of the present invention;

[0040] Figure 7 This is a control diagram of the pressure control unit of the present invention;

[0041] In the figure: 1. Superconducting magnet providing background magnetic field; 101. Superconducting coil; 102. Superconducting magnet cryostat; 103. Refrigerator for superconducting magnet; 104. Room temperature hole; 105. Copper braided flexible connection; 101a. Nb-Ti superconducting coil; 101b. Nb-Sn superconducting coil; 101c. High-temperature superconducting coil; 102a. First cold shield; 102b. High-temperature superconducting current lead; 102c. Vacuum layer; 103a. First cold head; 103b. Second cold head; 2. Superconducting wire sample test thermostat; 201. Helium tank; 202. Radiation shield; 203. Outer vacuum layer; 204. Refrigerator for sample test thermostat; 205, superconducting wire sample area; 206, liquid helium storage area; 207, liquid helium level gauge; 208, condenser; 209, nitrogen tank; 210, sample rod inlet; 211, safety valve; 212, second cold shield; 213, radiation plate; 214, liquid nitrogen infusion port; 201a, helium tank for superconducting wire sample area; 201b, helium tank for liquid helium storage area; 201c, refrigerator base; 201d, sample cavity; 4, sample rod; 401, superconducting wire sample; 5, pressure control unit; 501, heater; 502, pressure sensor; 503, pressure controller. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] See also Figure 1 - Figure 7 , the present invention provides a technical solution:

[0044] A superconducting wire critical current testing device includes a superconducting magnet 1 that provides a background magnetic field. A superconducting wire sample testing thermostat 2 is connected to the superconducting magnet 1 that provides the background magnetic field. A sample rod 4 is provided at the top center of the superconducting wire sample testing thermostat 2. The sample rod 4 passes through the superconducting wire sample testing thermostat 2 and is provided at the center of the superconducting magnet 1 that provides the background magnetic field.

[0045] The superconducting magnet 1 that provides the background magnetic field includes a superconducting coil 101, a superconducting magnet cryostat 102, a superconducting magnet refrigerator 103, a room temperature hole 104, and a copper braided flexible connection 105. The room temperature hole 104 is provided at the center of the superconducting magnet 1 that provides the background magnetic field. The superconducting coil 101 is provided outside the room temperature hole 104. The superconducting magnet cryostat 102 is provided outside the superconducting coil 101. One side of the superconducting coil 101 is also connected to the superconducting magnet refrigerator 103 via the copper braided flexible connection 105.

[0046] The superconducting wire sample test thermostat 2 includes a helium tank 201, a radiation shield 202, an outer vacuum layer 203, a refrigerator for the sample test thermostat 204, a superconducting wire sample area 205, a liquid helium storage area 206, a liquid helium level gauge 207, a condenser 208, a nitrogen tank 209, a sample rod inlet 210, a safety valve 211, a second cold shield 212 and a radiation plate 213. The superconducting wire sample test thermostat 2 is connected to the room temperature hole 104 of the superconducting magnet 1 that provides the background magnetic field. A wire sample area 205 is provided. A helium tank 201 is provided outside the superconducting wire sample area 205. A liquid helium storage area 206 and a liquid helium level gauge 207 are provided inside the helium tank 201. A radiation shield 202 is provided outside the helium tank 201. A radiation plate 213 is provided at the center of the radiation shield 202. An outer vacuum layer 203 is provided outside the radiation shield 202. A sample rod inlet 210 is provided at the center of the end of the superconducting wire sample test thermostat 2. A sample rod 4 is sleeved inside the sample rod inlet 210.

[0047] When a refrigerator 204 for a sample test thermostat is provided inside the superconducting wire sample test thermostat 2, the refrigerator 204 for the sample test thermostat is connected to the top of the helium tank 201. The refrigerator 204 for the sample test thermostat includes a condenser 208. The condenser 208 is connected to the cold head end of the refrigerator 204 for the sample test thermostat. The condenser 208 is connected to the top of the helium tank 201. The top of the condenser 208 is connected to a refrigerator base 201c. The refrigerator base 201c passes through the end of the superconducting wire sample test thermostat 2 and is fixedly connected to the end of the superconducting wire sample test thermostat 2. A pressure sensor 502 is provided on one side of the sample rod inlet 210, and a safety valve 211 is provided on the end surface of the superconducting wire sample test thermostat 2 on the other side of the sample rod inlet 210. The superconducting wire sample test thermostat 2 is also electrically connected to a pressure control unit 5 to ensure that the helium tank 201 maintains a slightly positive pressure state when the liquid helium is in a zero-volatility state.

[0048] When the superconducting wire sample testing thermostat 2 is not equipped with a sample testing refrigerator 204, a nitrogen tank 209 is located between the radiation shield 202 and the outer vacuum layer 203. A safety valve 211 is located on the side of the sample rod inlet 210, and a liquid nitrogen inlet 214 is located at the top of the nitrogen tank 209. The radiation shield 202 is made of aluminum alloy, and the outer vacuum layer 203 is made of 304 non-magnetic stainless steel. The superconducting wire sample testing thermostat 2 is a liquid helium low-volatility thermostat or a liquid helium micro-volatility thermostat.

[0049] In the present invention, the pressure control unit 5 further includes a heater 501 and a pressure controller 503 . The heater 501 is disposed inside the helium tank 201 , and the pressure sensor 502 is electrically connected to the pressure controller 503 .

[0050] In the present invention, helium tank 201 includes a superconducting wire sample area helium tank 201a, a liquid helium storage area helium tank 201b, and a sample chamber 201d. Superconducting wire sample area helium tank 201a is located within superconducting wire sample area 205, and liquid helium storage area helium tank 201b is located within liquid helium storage area 206. Helium tank 201 is made of 304 non-magnetic stainless steel.

[0051] In the present invention, a superconducting wire sample 401 is provided at one end of the sample rod 4 close to the helium tank 201a of the superconducting wire sample area.

[0052] In the present invention, the superconducting coil 101 includes a niobium-titanium superconducting coil 101a, a niobium-tin superconducting coil 101b and a high-temperature superconducting coil 101c. The high-temperature superconducting coil 101c, the niobium-tin superconducting coil 101b and the niobium-titanium superconducting coil 101a are arranged in sequence from the inside to the outside on the outside of the room temperature hole 104, and thermometer probes are respectively arranged on the upper and lower sides of the superconducting coil 101.

[0053] In the present invention, the superconducting magnet cryostat 102 includes a first cold shield 102a, a high-temperature superconducting current lead 102b, and a vacuum layer 102c. The first cold shield 102a is disposed outside the superconducting coil 101, and the vacuum layer 102c is disposed outside the first cold shield 102a. One side of the first cold shield 102a is connected to the superconducting magnet refrigerator 103. The vacuum layer 102c is made of 304 non-magnetic stainless steel.

[0054] In the present invention, the superconducting magnet refrigerator 103 includes a primary cold head 103a and a secondary cold head 103b. The primary cold head 103a is connected to the first cold shield 102a via a copper braided flexible connector 105, and the secondary cold head 103b is connected to the superconducting coil 101. The positive and negative leads of the superconducting magnet 1, which provides the background magnetic field, are also electrically connected to the superconducting coil 101 via high-temperature superconducting current leads 102b. The first cold shield 102a is made of aluminum alloy.

[0055] In the present invention, the aperture of the room temperature hole 104 is not less than 120 mm, the surface diameter of the superconducting wire sample area 205 is not greater than 120 mm, the outer diameter of the superconducting wire sample area 205 is smaller than the aperture of the room temperature hole 104, and the superconducting wire sample area 205 is connected to the room temperature hole 104 by means of an axial hole.

[0056] The present invention also provides a technical solution:

[0057] A method for testing a superconducting wire critical current test device comprises the following steps:

[0058] S100, performing magnetic field measurement on the superconducting magnet 1 providing the background magnetic field by cooling down;

[0059] S110, cooling the superconducting wire sample test thermostat 2;

[0060] S120, exciting the superconducting magnet 1 that provides the background magnetic field;

[0061] S130, installing the sample rod 4, and placing the sample rod 4 containing the superconducting wire sample 401 into the superconducting wire sample test thermostat 2;

[0062] S140, adjusting the magnetic field strength of the superconducting magnet 1 providing the background magnetic field;

[0063] S150, conducting a power-on test on the superconducting wire sample 401;

[0064] S160, adjusting the magnetic field strength of the superconducting magnet 1 providing the background magnetic field again, and taking out the superconducting wire sample 401 after the power-on test;

[0065] S170 , after the test is completed, demagnetize the superconducting magnet 1 that provides the background magnetic field.

[0066] In the present invention, when cooling the superconducting wire sample test thermostat 2, the superconducting wire sample test thermostat 2 is cooled by a sample test thermostat refrigerator 204 or by liquid nitrogen;

[0067] When cooling the superconducting wire sample test thermostat 2 with liquid nitrogen, first use liquid nitrogen to cool the helium tank 201 of the superconducting wire sample test thermostat 2. After the helium tank 201 is soaked in liquid nitrogen for at least half an hour, the liquid nitrogen is removed and the helium tank 201 is replaced and cleaned at least three times with helium. Then, liquid nitrogen is filled into the nitrogen tank 209. After the liquid nitrogen is full, liquid helium is started to be filled into the helium tank 201 for cooling. The liquid helium level in the helium tank 201 is observed using the liquid helium level gauge 207. When the liquid helium level reaches the designed target value, the helium infusion is stopped and the infusion line is unplugged.

[0068] When the superconducting wire sample test thermostat 2 is cooled by the sample test thermostat refrigerator 204, liquid nitrogen is first used to cool the helium tank 201 of the superconducting wire sample test thermostat 2. The helium tank 201 is soaked in liquid nitrogen for at least half an hour and then the liquid nitrogen is removed. The helium tank 201 is then replaced and cleaned with helium gas at least three times. After the sample rod inlet 210 is sealed, the helium tank 201 is kept in a slightly positive pressure state. The sample test thermostat refrigerator 204 is turned on to cool the radiation shield 202 of the superconducting wire sample test thermostat 2. After the temperature at the far end of the radiation shield 202 falls below 60K, liquid helium is fed into the helium tank 201 for cooling. The liquid helium level in the helium tank 201 is monitored using a liquid helium level gauge 207. When the liquid helium level reaches the designed target value, the helium infusion is stopped and the infusion line is disconnected. After the pressure value of the pressure control unit 5 is set to 1-3 kPa via the pressure controller 503, the heater 501 in the helium tank 201 begins to operate. At this point, the pressure in the helium tank 201 stabilizes at 1-3 kPa, and the superconducting wire sample test thermostat 2 maintains a zero-volatility state of liquid helium.

[0069] In the present invention, the magnetic field strength of the superconducting magnet 1 providing the background magnetic field is not less than 10 Tesla.

[0070] Example 1: When the superconducting wire sample test thermostat 2 is provided with a sample test thermostat refrigerator 204 as an example. Figure 5 As shown, first, the superconducting magnet 1 providing the background magnetic field is cooled and magnetically measured; the superconducting magnet cryostat 102 of the superconducting magnet 1 providing the background magnetic field is evacuated using a molecular pump, and the vacuum degree is higher than 1*10 -3 After pa, the superconducting magnet refrigerator 103 is turned on, and the superconducting magnet 1 providing the background magnetic field begins to cool down; after the temperature of the superconducting coil 101 of the superconducting magnet 1 providing the background magnetic field is lower than 4.2K, the superconducting magnet 1 providing the background magnetic field is subjected to a power-on excitation test, and the magnetic field is tested with a gaussmeter. After reaching the target magnetic field, the magnetic field verification of the superconducting magnet 1 providing the background magnetic field is completed; in order to better carry out subsequent work, the superconducting magnet 1 providing the background magnetic field is first demagnetized and kept in a low-temperature state before testing the sample.

[0071] Cool the superconducting wire sample test thermostat 2; first use liquid nitrogen to cool the helium tank 201 of the superconducting wire sample test thermostat 2, soak the helium tank 201 in liquid nitrogen for at least half an hour, then remove the liquid nitrogen, and use helium to replace and clean the helium tank 201 for at least three times; after sealing the sample rod inlet 210, keep the helium tank 201 in a slightly positive pressure state, open the sample test thermostat and use the refrigerator 204 to cool the radiation screen 202 of the superconducting wire sample test thermostat 2, and wait until the far end of the radiation screen 202 After the temperature falls below 60K, liquid helium is fed into the helium tank 201 for cooling. The liquid helium level in the helium tank 201 is monitored using a liquid helium level gauge 207. When the liquid helium level reaches the designed target value, the helium infusion is stopped and the infusion line is disconnected. After the pressure value of the pressure control unit 5 is set to 1-3 kPa via the pressure controller 503, the heater 501 in the helium tank 201 begins to operate. At this point, the pressure in the helium tank 201 is stabilized at 1-3 kPa, and the superconducting wire sample test thermostat 2 maintains a zero-volatility state of liquid helium.

[0072] The superconducting magnet 1 providing the background magnetic field is excited; the superconducting magnet 1 providing the background magnetic field is excited by a superconducting power supply until the magnetic field value required for testing the superconducting wire sample 401 is reached and maintained.

[0073] Install the sample rod 4 and place the sample rod 4 containing the superconducting wire sample 401 into the superconducting wire sample test thermostat 2; first open the sealing plate of the sample rod entrance 210, and then slowly place the sample rod 4 containing the superconducting wire sample 401 into the superconducting wire sample test thermostat 2.

[0074] The superconducting wire sample 401 is subjected to a power-on test; first, the operation of the sample test thermostat with the refrigerator 204 is stopped, and then the sample rod 4 is energized by the test power supply to perform a performance test on the superconducting wire sample 401; after the test of the superconducting wire sample 401 is completed, the sample rod 4 is slowly lifted out of the superconducting wire sample test thermostat 2 to replace the superconducting wire sample 401, and then the sample rod entrance 210 is closed.

[0075] The magnetic field strength of the superconducting magnet 1 providing the background magnetic field is adjusted again, and the superconducting wire sample 401 after the power-on test is taken out;

[0076] After the test is completed, the superconducting magnet 1 providing the background magnetic field is demagnetized, the sample test thermostat refrigerator 204 is turned on, and the superconducting wire sample test thermostat 2 maintains a zero-volatility state of liquid helium.

[0077] When the sample test thermostat refrigerator 204 is turned on, see Figure 7 The pressure control unit 5 is always running to ensure that the helium tank 201 maintains a slightly positive pressure. After the sample test thermostat refrigerator 204 is turned off, the pressure control unit 5 can be turned off to save liquid helium.

[0078] While testing low-temperature superconducting wires in a liquid helium environment offers high efficiency and test data reliability, this method consumes a significant amount of liquid helium. Therefore, adding a sample test thermostat refrigerator 204 to the superconducting wire sample test thermostat 2 effectively condenses and maintains the liquid helium. Placing the superconducting magnet 1, which provides the background magnetic field, outside the liquid helium environment effectively reduces liquid helium consumption, prevents quenching of the superconducting magnet 1, which provides the background magnetic field, from affecting device operation, and improves the robustness of the test device.

[0079] Example 2: Consider the case where the superconducting wire sample test thermostat 2 is not equipped with a sample test thermostat refrigerator 204. Since the sample test thermostat refrigerator 204 consumes a certain amount of power, to reduce production costs, the sample test thermostat refrigerator 204 is not installed on the superconducting wire sample test thermostat 2. Thus, a small amount of liquid helium evaporates during operation of the superconducting wire sample test thermostat 2.

[0080] like Figure 6 As shown, the difference between this embodiment and embodiment 1 is that:

[0081] In this embodiment, the sample test thermostat refrigerator 204 is not installed. The structure of the sample test thermostat refrigerator 204 area is consistent with that of other areas, and there is no refrigerator base 201c or other structures. The superconducting wire sample test thermostat 2 consists of a helium tank 201, an outer vacuum layer 203, a nitrogen tank 209, and a second cold shield 212. The nitrogen tank 209 is an annular cylindrical structure outside the helium tank 201, which serves to form the temperature gradient of the superconducting wire sample test thermostat and is filled with liquid nitrogen during testing. The nitrogen tank 209 is generally made of aluminum alloy. The second cold shield 212 is an extended radiation shield of the nitrogen tank 209 in the superconducting wire sample area 205. Because the superconducting wire sample area 205 is relatively small and lacks space for the nitrogen tank 209, the second cold shield 212 is designed to surround the helium tank 201 in the superconducting wire sample area 205.

[0082] First, the superconducting magnet 1 providing the background magnetic field is cooled and magnetically measured; the superconducting magnet cryostat 102 of the superconducting magnet 1 providing the background magnetic field is evacuated using a molecular pump, and the vacuum degree is higher than 1*10 -3 After pa, the superconducting magnet refrigerator 103 is turned on, and the superconducting magnet 1 providing the background magnetic field begins to cool down; after the temperature of the superconducting coil 101 of the superconducting magnet 1 providing the background magnetic field is lower than 4.2K, the superconducting magnet 1 providing the background magnetic field is subjected to a power-on excitation test, and the magnetic field is tested with a gaussmeter. After reaching the target magnetic field, the magnetic field verification of the superconducting magnet 1 providing the background magnetic field is completed; in order to better carry out subsequent work, the superconducting magnet 1 providing the background magnetic field is first demagnetized and kept in a low-temperature state before testing the sample.

[0083] Cool the superconducting wire sample test thermostat 2; first use liquid nitrogen to cool the helium tank 201 of the superconducting wire sample test thermostat 2. After soaking the helium tank 201 in liquid nitrogen for at least half an hour, remove the liquid nitrogen and use helium to replace and clean the helium tank 201 for at least three times; then fill the nitrogen tank 209 with liquid nitrogen. After the liquid nitrogen is full, start filling the helium tank 201 with liquid helium for cooling. Use the liquid helium level gauge 207 to observe the liquid helium level in the helium tank 201. When the designed target value is reached, stop infusing helium and unplug the infusion line.

[0084] The superconducting magnet 1 providing the background magnetic field is excited; the superconducting magnet 1 providing the background magnetic field is excited by a superconducting power supply until the magnetic field value required for testing the superconducting wire sample 401 is reached and maintained.

[0085] Install the sample rod 4 and place the sample rod 4 containing the superconducting wire sample 401 into the superconducting wire sample test thermostat 2; first open the sealing plate of the sample rod entrance 210, and then slowly place the sample rod 4 containing the superconducting wire sample 401 into the superconducting wire sample test thermostat 2.

[0086] The superconducting wire sample 401 is subjected to a power-on test; first, the operation of the sample test thermostat with the refrigerator 204 is stopped, and then the sample rod 4 is energized by the test power supply to perform a performance test on the superconducting wire sample 401; after the test of the superconducting wire sample 401 is completed, the sample rod 4 is slowly lifted out of the superconducting wire sample test thermostat 2 to replace the superconducting wire sample 401, and then the sample rod entrance 210 is closed.

[0087] The magnetic field strength of the superconducting magnet 1 providing the background magnetic field is adjusted again, and the superconducting wire sample 401 after the power-on test is taken out;

[0088] After the test is completed, the superconducting magnet 1 providing the background magnetic field is demagnetized.

[0089] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description. It is intended that all variations within the meaning and range of equivalents of the claims be embraced herein, and any reference signs in the claims should not be construed as limiting the claims to which they relate.

[0090] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A superconducting wire critical current testing device, comprising a superconducting magnet (1) for providing a background magnetic field, characterized in that: The superconducting magnet (1) providing the background magnetic field is internally connected to a superconducting wire sample test thermostat (2), a sample rod (4) is provided through the center of the top of the superconducting wire sample test thermostat (2), and the sample rod (4) passes through the superconducting wire sample test thermostat (2) and is provided at the center of the superconducting magnet (1) providing the background magnetic field; The superconducting magnet (1) for providing a background magnetic field comprises a superconducting coil (101), a superconducting magnet cryostat (102), a superconducting magnet refrigerator (103), a room temperature hole (104) and a copper braided flexible connection (105); a room temperature hole (104) is provided at the center of the interior of the superconducting magnet (1) for providing a background magnetic field, a superconducting coil (101) is provided outside the room temperature hole (104), a superconducting coil (101) is provided outside the superconducting coil (101), and a superconducting magnet cryostat (102) is provided outside the superconducting coil (101); one side of the superconducting coil (101) is further connected to the superconducting magnet refrigerator (103) via a copper braided flexible connection (105); The superconducting wire sample test thermostat (2) comprises a helium tank (201), a radiation shield (202), an outer vacuum layer (203), a refrigerator for the sample test thermostat (204), a superconducting wire sample area (205), a liquid helium storage area (206), a liquid helium level gauge (207), a condenser (208), a nitrogen tank (209), a sample rod inlet (210), a safety valve (211), a second cold shield (212) and a radiation plate (213). A superconducting wire sample is provided at a connection between the superconducting wire sample test thermostat (2) and a room temperature hole (104) of a superconducting magnet (1) providing a background magnetic field. A superconducting wire sample test thermostat (205) is provided with a helium tank (201) outside the superconducting wire sample zone (205), a liquid helium storage zone (206) and a liquid helium level gauge (207) are provided inside the helium tank (201), a radiation screen (202) is provided outside the helium tank (201), a radiation plate (213) is provided at the center of the radiation screen (202), an outer vacuum layer (203) is provided outside the radiation screen (202), a sample rod inlet (210) is provided at the center of the end of the superconducting wire sample test thermostat (2), and a sample rod (4) is sleeved inside the sample rod inlet (210); When a sample test thermostat refrigerator (204) is provided inside the superconducting wire sample test thermostat (2), the top of the helium tank (201) is connected to the sample test thermostat refrigerator (204), the sample test thermostat refrigerator (204) includes a condenser (208), the condenser (208) is connected to the cold head end of the sample test thermostat refrigerator (204), the condenser (208) is connected to the top of the helium tank (201), and the top of the condenser (208) is connected to the A refrigerator base (201c) is provided, the refrigerator base (201c) passes through the end of the superconducting wire sample test thermostat (2) and is fixedly connected to the end of the superconducting wire sample test thermostat (2); a pressure sensor (502) is provided on one side of the sample rod inlet (210); a safety valve (211) is provided on the end surface of the superconducting wire sample test thermostat (2) on the other side of the sample rod inlet (210); and the superconducting wire sample test thermostat (2) is also electrically connected to a pressure control unit (5); When a sample test thermostat refrigerator (204) is not provided inside the superconducting wire sample test thermostat (2), a nitrogen tank (209) is provided between the radiation screen (202) and the outer vacuum layer (203), a safety valve (211) is provided on the side of the sample rod inlet (210), and a liquid nitrogen infusion port (214) is also provided on the top of the nitrogen tank (209).

2. The superconducting wire critical current testing device according to claim 1, characterized in that: The pressure control unit (5) further comprises a heater (501) and a pressure controller (503). The heater (501) is arranged inside the helium tank (201), and the pressure sensor (502) is electrically connected to the pressure controller (503).

3. The superconducting wire critical current testing device according to claim 1, characterized in that: The helium tank (201) comprises a superconducting wire sample area helium tank (201a), a liquid helium storage area helium tank (201b) and a sample cavity (201d); the superconducting wire sample area helium tank (201a) is arranged inside the superconducting wire sample area (205), and the liquid helium storage area helium tank (201b) is arranged inside the liquid helium storage area (206).

4. The superconducting wire critical current testing device according to claim 3, characterized in that: A superconducting wire sample (401) is provided at one end of the sample rod (4) close to the helium tank (201a) of the superconducting wire sample area.

5. The superconducting wire critical current testing device according to claim 1, characterized in that: The superconducting coil (101) comprises a niobium-titanium superconducting coil (101a), a niobium-tin superconducting coil (101b) and a high-temperature superconducting coil (101c); the high-temperature superconducting coil (101c), the niobium-tin superconducting coil (101b) and the niobium-titanium superconducting coil (101a) are sequentially arranged on the outside of the room-temperature hole (104) from the inside out, and thermometer probes are respectively arranged on the upper and lower sides of the superconducting coil (101).

6. The superconducting wire critical current testing device according to claim 1, characterized in that: The superconducting magnet cryostat (102) comprises a first cold shield (102a), a high-temperature superconducting current lead (102b) and a vacuum layer (102c); the first cold shield (102a) is arranged outside the superconducting coil (101); the vacuum layer (102c) is arranged outside the first cold shield (102a); and one side of the first cold shield (102a) is connected to a refrigerator (103) for the superconducting magnet.

7. The superconducting wire critical current testing device according to claim 6, characterized in that: The superconducting magnet refrigerator (103) comprises a primary cold head (103a) and a secondary cold head (103b), wherein the primary cold head (103a) is connected to a first cold shield (102a), and the secondary cold head (103b) is connected to a superconducting coil (101) via a copper braided flexible connection (105). The positive and negative leads of the superconducting magnet (1) providing a background magnetic field are also electrically connected to the superconducting coil (101) via a high-temperature superconducting current lead (102b).

8. The method for testing a superconducting wire critical current testing device according to any one of claims 1 to 7, characterized in that: The following steps are involved: S100, cooling and measuring the magnetic field of the superconducting magnet (1) providing the background magnetic field; S110, cooling the superconducting wire sample test thermostat (2); S120, exciting the superconducting magnet (1) that provides the background magnetic field; S130, installing the sample rod (4), and placing the sample rod (4) containing the superconducting wire sample (401) into the superconducting wire sample test thermostat (2); S140, adjusting the magnetic field strength of the superconducting magnet (1) providing the background magnetic field; S150, conducting a power-on test on the superconducting wire sample (401); S160, re-adjusting the magnetic field strength of the superconducting magnet (1) providing the background magnetic field, and taking out the superconducting wire sample (401) after the power-on test; S170: After the test is completed, the superconducting magnet (1) providing the background magnetic field is demagnetized.

9. The method for testing a superconducting wire critical current testing device according to claim 8, characterized in that: When cooling the superconducting wire sample test thermostat (2), the superconducting wire sample test thermostat (2) is cooled by a sample test thermostat refrigerator (204) or by liquid nitrogen; When the superconducting wire sample test thermostat (2) is cooled by liquid nitrogen, the helium tank (201) of the superconducting wire sample test thermostat (2) is first cooled by liquid nitrogen, the liquid nitrogen is removed after the helium tank (201) is soaked in liquid nitrogen for not less than half an hour, and the helium tank (201) is replaced and cleaned by helium gas for not less than three times; then, liquid nitrogen is filled into the nitrogen tank (209), and after the liquid nitrogen is full, liquid helium is started to be filled into the helium tank (201) for cooling, and the liquid helium level in the helium tank (201) is observed by a liquid helium level gauge (207). When the liquid helium level reaches the designed target value, the helium infusion is stopped, and the infusion pipeline is unplugged; When the superconducting wire sample test thermostat (2) is cooled by the sample test thermostat refrigerator (204), the helium tank (201) of the superconducting wire sample test thermostat (2) is first cooled by using liquid nitrogen, the liquid nitrogen is removed after the helium tank (201) is soaked in liquid nitrogen for not less than half an hour, and the helium tank (201) is replaced and cleaned by using helium gas for not less than three times; after the sample rod inlet (210) is closed, the helium tank (201) is kept in a slightly positive pressure state, and the sample test thermostat refrigerator (204) is turned on to cool the radiation screen (202) of the superconducting wire sample test thermostat (2) After the temperature at the far end of the radiation screen (202) is lower than 60K, liquid helium is started to be filled into the helium tank (201) for cooling. The liquid helium level in the helium tank (201) is observed by using a liquid helium level gauge (207). After reaching the designed target value, the liquid helium infusion is stopped and the infusion pipeline is unplugged. After the pressure value of the pressure control unit (5) is set to 1-3KPa through the pressure controller (503), the heater (501) in the helium tank (201) starts to work. At this time, the pressure in the helium tank (201) is stabilized at 1-3KPa, and the superconducting wire sample test thermostat (2) maintains a zero-volatility state of liquid helium.

10. The method for testing a superconducting wire critical current testing device according to claim 8, wherein: The magnetic field strength of the superconducting magnet (1) providing the background magnetic field is not less than 10 Tesla.

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