Critical characteristic test sample rod for short sample of high-temperature superconducting material

Abstract

The invention discloses a critical characteristic test sample rod for a short sample of a high-temperature superconducting material, which comprises a sleeve, the bottom of the sleeve is detachably connected with a support mechanism, and when the support mechanism is arranged in a refrigerant environment, a background magnet is arranged outside the short sample of the superconducting material to be tested; the constant-temperature cover is driven by the lifting mechanism to move downwards to form a test chamber of a to-be-tested superconducting material short sample, the temperature in the test chamber is adjusted and changed through the heater, and the to-be-tested superconducting material short sample is in electric conduction connection through the drainage circuit. Therefore, the to-be-tested superconducting material short sample is subjected to critical current testing in environments with different temperatures and different magnetic field intensities. According to the application, the temperature in the test chamber can be regulated and controlled through the heater, the test magnetic field intensity is regulated and controlled through the background magnet, the critical current of the to-be-tested superconducting material short sample at different temperatures and different magnetic fields can be measured, the operation and application are convenient, and thus the accuracy of measuring the critical current can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of critical test of short samples of superconducting materials, and in particular to a critical characteristic test sample rod of a short sample of high-temperature superconducting material. Background Art

[0002] Since Bednorz and Muller first discovered high-temperature superconductors in 1986, they have been widely studied for their high critical temperature (T C ) and the upper critical magnetic field (H C2 ) has attracted widespread attention. After years of development, the performance of high-temperature superconductors (HTS) has been greatly improved and the cost has been reduced. The temperature parameter has always been considered to affect the critical current (I C ) is a key parameter. In the study of superconductor stability, it is necessary to measure the temperature of C These parameters are also needed when designing magnets that operate at temperatures other than 4.2K or 77K.

[0003] At the University of Geneva and the National Institute of Standards and Technology (NI ST), a helium flow in a variable temperature insert (VTI) is used to cool the sample. Two Cernox thermometers above and below the sample are used to monitor the temperature and control its uniformity. The helium flows along the length of the sample. As a result, there is an inevitable temperature gradient along the sample. There are many examples of vacuum chamber designs using helium exchange gas. Typically in this approach, the sample space is vacuum sealed, and a small amount of controlled helium is introduced into the sealed space to cool the sample. Vacuum feedback for current leads and signal leads usually requires a special sealing structure, and it is difficult to determine the amount of helium to obtain better temperature control accuracy and at the same time reduce the time required for the temperature controller to stabilize, resulting in the measurement current usually being at a low level. Summary of the invention

[0004] The object of the present invention is to provide a critical characteristics test sample rod for a short sample of a high-temperature superconducting material, which is used to solve the shortcomings mentioned in the prior art and can measure the critical current (I) of a short sample of a high-temperature superconducting material at different temperatures (4.2-80K) and different magnetic fields (0-15T). C ).

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A critical characteristic test sample rod for a short sample of a high-temperature superconducting material comprises a sleeve, a support mechanism and a current drainage circuit, wherein the bottom of the sleeve is detachably connected to the support mechanism, a constant temperature cover is slidably connected to the support mechanism, a lifting mechanism connected to the constant temperature cover is provided on the sleeve, and the constant temperature cover is driven to move up and down along the height direction of the support mechanism by the lifting mechanism, a sample holder is provided at the bottom of the support mechanism, a heater is provided in the sample holder, a short sample of a superconducting material to be tested is welded and fixed on the sample holder, and the short sample of the superconducting material to be tested is electrically connected through the current drainage circuit;

[0007] Among them, when the supporting mechanism is placed in a refrigerant environment, a background magnet is set outside the short sample of superconducting material to be tested, and the constant temperature cover is driven downward by the lifting mechanism to form a test chamber for the short sample of superconducting material to be tested. The temperature in the test chamber is changed by adjusting the heater so that the short sample of superconducting material to be tested can be tested for critical current in different temperatures and different magnetic field strength environments.

[0008] As a further solution of the present invention: the supporting mechanism includes an upper insulating partition and a lower insulating partition, the upper insulating partition is connected to the bottom end of the sleeve by bolts, the lower insulating partition is used to support and fix the sample rack, and the lower insulating partition is fixedly installed on the lower end plate, the upper insulating partition and the lower insulating partition are connected by a plurality of stainless steel supports, a plurality of middle insulating partitions are arranged on the stainless steel supports at intervals, and the stainless steel supports are used to slide against the side walls of the constant temperature cover.

[0009] As a further solution of the present invention: the current diversion circuit includes two upper current leads, two middle current leads and two lower current leads, the upper current leads are inserted and connected to the flange, the flange is fixedly connected to the top end of the sleeve, and the tail end of the upper current leads extends out of the sleeve and is welded and fixed to the middle current leads, the middle current leads are arranged along the height direction of the supporting mechanism and are welded and fixed to the lower current leads, the lower current leads are welded and fixed to the current contacts provided on the sample holder, and the short sample of the superconducting material to be tested is welded and fixed to the current contacts to form a test current loop of the short sample of the superconducting material to be tested.

[0010] As a further solution of the present invention: the upper current lead is a wire with a hollow structure, and superconducting wires and superconducting tapes are welded in the inner cavity of the upper current lead.

[0011] As a further solution of the present invention: the middle current lead and the lower current lead are both conductors of strip-shaped structure, and grooves are provided on the outer surfaces of the middle current lead and the lower current lead, and superconducting tapes are welded in the grooves.

[0012] As a further solution of the present invention: the sample rack is provided with two thermometers which are arranged flush with the short sample of the superconducting material to be tested in the horizontal direction. The thermometers are used to detect the test temperature of the short sample of the superconducting material to be tested in real time and feed it back to the temperature controller. The temperature controller is used to adjust the heating temperature of the heater.

[0013] As a further solution of the present invention: the lifting mechanism includes a pull-out rod and a pull rod fixer, the tail end of the pull-out rod is fixedly connected to the constant temperature cover, the pull-out rod is inserted and connected to the flange at the top end of the sleeve, and the pull rod fixer is used on the flange to keep the insertion position of the pull-out rod fixed.

[0014] As a further solution of the present invention: the number of short samples of superconducting material to be tested is at least two, and the short samples of superconducting material to be tested are connected to a signal acquisition line, the signal acquisition line is arranged in a lower cable tube, the lower cable tube is arranged along the height direction of the supporting mechanism, the top end of the lower cable tube is connected to the upper cable tube arranged in the sleeve, and the upper cable tube is inserted and connected to a flange at the top end of the sleeve.

[0015] As a further solution of the present invention: the top end of the thermostatic cover is inserted and connected to the bottom end of the ventilation pipe, and the ventilation pipe is inserted and connected to the flange at the top end of the sleeve.

[0016] As a further solution of the present invention: when the short sample of the superconducting material to be tested is subjected to critical current testing in different temperature and different magnetic field strength environments, the different temperature ranges from 4.2 to 80K, and the different magnetic field strength ranges from 0 to 15T.

[0017] Beneficial effects of the present invention:

[0018] (1) During the use of the critical characteristics test sample rod of the present application, under the condition of stable heating test temperature, the current diversion circuit forms a current test loop for the short sample of the superconducting material to be tested, and the constant temperature cover keeps the temperature in the test chamber uniform. The temperature in the test chamber can be regulated by the heater, and the test magnetic field strength can be regulated by the background magnet. The critical current (I) of the short sample of the superconducting material to be tested under different temperatures and different magnetic fields can be measured. C ), easy to operate and apply, thus improving the accuracy of measuring critical current;

[0019] (2) The layout and design of the current diversion circuit in the present application are reasonable and can meet the requirements of large current testing exceeding 2000A during testing. In addition, the current leads in the current diversion circuit can be welded with superconducting materials, so that the welding of superconducting materials can greatly reduce the heat generated during the operation of the current leads, thereby reducing the impact of the heat generated during the operation of the current leads. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below in conjunction with the accompanying drawings.

[0021] Figure 1 It is a schematic diagram of the structure of the present invention;

[0022] Figure 2 is a top view of the present invention;

[0023] Figure 3 It is a schematic diagram of the support mechanism, the constant temperature cover and the sample test frame arranged at the bottom of the sleeve of the present invention.

[0024] In the figure: 1. pull rod; 2. pull rod holder; 3. upper cable tube; 4. vent pipe; 5. upper current lead; 6. sleeve; 7. middle insulating partition; 8. stainless steel support; 9. constant temperature cover; 10. lower current lead; 11. lower end plate; 12. lower insulating partition; 13. current contact; 14. middle current lead; 15. lower cable tube; 16. flange; 17. upper insulating partition. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be understood that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention; in the description of the present invention, the meaning of "multiple" and "several" is at least two, for example two, three, etc., unless otherwise clearly and specifically defined.

[0027] See also Figures 1 to 3As shown, the present invention is a critical characteristics test sample rod for a short sample of a high-temperature superconducting material, comprising a sleeve 6, a supporting mechanism and a drainage circuit. The bottom of the sleeve 6 is detachably connected to the supporting mechanism, and a constant temperature cover 9 is slidably connected to the supporting mechanism. A lifting mechanism connected to the constant temperature cover 9 is provided on the sleeve 6, and the constant temperature cover 9 is driven to move up and down along the height direction of the supporting mechanism by the lifting mechanism. A sample rack is provided at the bottom of the supporting mechanism, a heater is provided in the sample rack, and a short sample of the superconducting material to be tested is welded and fixed on the sample rack, and the short sample of the superconducting material to be tested is electrically connected through the drainage circuit.

[0028] Among them, when the supporting mechanism is placed in a refrigerant environment, a background magnet is set outside the short sample of the superconducting material to be tested, and the constant temperature cover 9 is driven downward by the lifting mechanism to form a test chamber for the short sample of the superconducting material to be tested. The temperature in the test chamber is changed by adjusting the heater so that the short sample of the superconducting material to be tested can be tested for critical current in different temperatures and different magnetic field strength environments.

[0029] During the use of the critical characteristic test sample rod of the present application, the short sample of the superconducting material to be tested is welded and fixed on the sample holder in advance, the support mechanism positions and supports the sample holder, and then the constant temperature cover 9 is pushed down by the lifting mechanism to facilitate placing the short sample of the superconducting material to be tested in the inner cavity of the constant temperature cover 9. During the test operation, the short sample of the superconducting material to be tested in the constant temperature cover 9 is placed in a refrigerant environment, and a background magnet is set outside the short sample of the superconducting material to be tested. The heater is used to heat the short sample in the test chamber, and the nitrogen generated by the evaporation of the liquid nitrogen refrigerant will enter the constant temperature cover 9. As the constant temperature The increase in gas in the cover 9 presses down the liquid nitrogen level to make the test chamber a dry gas chamber, which can maintain the short sample of the superconducting material to be tested from contacting the refrigerant. Under the condition of stable heating test temperature, the diversion circuit forms a current test loop for the short sample of the superconducting material to be tested, and the constant temperature cover 9 keeps the temperature in the test chamber uniform. The present application adjusts the temperature in the test chamber by a heater and adjusts the test magnetic field strength by a background magnet. The critical current of the short sample of the superconducting material to be tested under different temperatures and different magnetic fields can be measured. The operation and application are convenient, thereby improving the accuracy of measuring the critical current.

[0030] In this specific embodiment, the supporting mechanism includes an upper insulating partition 17 and a lower insulating partition 12. The upper insulating partition 17 is connected to the bottom end of the sleeve 6 by bolts. The lower insulating partition 12 is used to support and fix the sample rack, and the lower insulating partition 12 is fixedly installed on the lower end plate 11. The upper insulating partition 17 and the lower insulating partition 12 are connected by a plurality of stainless steel supports 8. A plurality of middle insulating partitions 7 are arranged on the stainless steel supports 8 at intervals, and the stainless steel supports 8 are used to be set in sliding contact with the side wall of the constant temperature cover 9.

[0031] In the present application, an upper insulating partition 17, a middle insulating partition 7, a lower insulating partition 12 and a stainless steel support 8 are assembled into a support mechanism, which can ensure the mechanical strength of the sample rack support and ensure the test stability of the support mechanism placed in the refrigerant. A short sample of the superconducting material to be tested is set on the sample rack to facilitate the stable downward movement of the constant temperature cover 9 to the test station. It should be understood that the insulating partitions in the support mechanism are respectively made of G10 composite materials synthesized by glass fiber cloth and epoxy resin. The G10 composite material will not be penetrated by the evaporating gas and liquid of the liquid nitrogen refrigerant, and has the characteristics of insulation, acid and alkali resistance and wear resistance, which helps to improve the service life of the support mechanism.

[0032] In this specific embodiment, the current diversion circuit includes two upper current leads 5, two middle current leads 14 and two lower current leads 10. The upper current lead 5 is inserted and connected to the flange 16, the flange 16 is fixedly connected to the top end of the sleeve 6, and the tail end of the upper current extends out of the sleeve 6 and is welded and fixed to the middle current lead 14. The middle current lead 14 is arranged along the height direction of the supporting mechanism and is welded and fixed to the lower current lead 10. The lower current lead 10 is welded and fixed to the current contact 13 set on the sample rack, and the short sample of the superconducting material to be tested is welded and fixed on the current contact 13 to form a test current loop for the short sample of the superconducting material to be tested; the current diversion circuit layout design in the present application is reasonable and can meet the test requirements of withstanding large currents exceeding 2000A during testing.

[0033] In this specific embodiment, the upper current lead 5 is a wire with a hollow structure. Superconducting wire and superconducting tape are welded in the inner cavity of the upper current. The superconducting wire can be a NbTi superconducting wire, and the superconducting tape can be a Bi-2223 superconducting wire. The upper current lead 5 is designed with a hollow structure, and many holes are designed around it to dissipate the heat generated by the large current during the test. In addition, because the bottom is close to the liquid helium surface, welding superconducting materials can greatly reduce the heat generated during the operation of the current lead, thereby reducing the impact of the heat generated during the operation of the current lead.

[0034] In this specific embodiment, the middle current lead 14 and the lower current lead 10 are both conductors with strip-shaped structures, and grooves are provided on the outer surfaces of the middle current lead 14 and the lower current lead 10, and superconducting tapes are welded in the provided grooves; the middle current lead 14 and the lower current lead 10 can be welded with Bi-2223 superconducting tapes respectively, which can greatly reduce the heat generated during the operation of the current leads, thereby reducing the impact of the heat generated during the operation of the current leads; in addition, the lower current lead 10 is inevitably designed to be bent due to the need to connect samples. In order to avoid excessive heat generation due to the bending, 4 layers of YBCO tapes can be welded on its outside for heat dissipation.

[0035] In this specific embodiment, two thermometers are provided on the sample rack, which are arranged flush with the short sample of the superconducting material to be tested in the horizontal direction. The sample is theoretically installed in the horizontal direction, and no temperature gradient is generated, which can ensure the accuracy of the temperature detected by the thermometer. The thermometer is used to detect the test temperature of the short sample of the superconducting material to be tested in real time, and feed it back to the temperature controller, and the temperature controller is used to adjust the heating temperature of the heater; the thermometer in this application can use a Cernox thermometer to monitor the sample temperature. Specifically, the heater is connected to the temperature controller, and the sample measurement can be started after the temperatures of the two thermometers are stable. After completing the measurement of one temperature, another temperature can be set by the temperature controller and then measured. This process is feedback controlled by the thermometer in cooperation with the temperature controller, and this process is repeated.

[0036] In this specific embodiment, the lifting mechanism includes a pull-out rod 1 and a pull-rod holder 2, the tail end of the pull-out rod 1 is fixedly connected to the constant temperature cover 9, the pull-out rod 1 is inserted and connected to the flange 16 at the top end of the sleeve 6, and the pull-out rod 1 is kept fixed in the insertion position by the pull-rod holder 2 on the flange 16; during the operation of the lifting mechanism, the pull-out action is guided by the pull-out rod 1 along the flange 16 on the sleeve 6, so as to facilitate the up and down movement of the constant temperature cover 9, so that the constant temperature cover 9 that moves downward places the short sample of the superconducting material to be tested in the test chamber, so as to complete the critical current test, and the constant temperature cover 9 that moves upward facilitates the welding and fixing of the short sample of the superconducting material to be tested on the sample rack, which is convenient for operation; after the up and down movement is completed, the insertion position of the pull-out rod 1 is kept fixed by the pull-rod holder 2.

[0037] In this specific embodiment, at least two short samples of superconducting material to be tested are tested, and a signal acquisition line is connected to the short samples of superconducting material to be tested, the signal acquisition line is arranged in the lower cable tube 15, the lower cable tube 15 is arranged along the height direction of the support mechanism, the top of the lower cable tube 15 is connected to the upper cable tube 3 arranged in the sleeve 6, and the upper cable tube 3 is inserted and connected to the flange 16 at the top end of the sleeve 6; in the testing process of the short samples of superconducting material to be tested in the present application, the length of the short samples of superconducting material to be tested is about 5 cm, the voltage tap of one short sample of superconducting material to be tested can be used for measurement, and the voltage tap of another short sample of superconducting material to be tested can be used to measure the joint resistance. It should be noted that in order to avoid the influence of the Lorentz force generated by the magnetic field on the strip, the sample must be fixed in advance using low-temperature glue.

[0038] In this specific embodiment, the top of the constant temperature cover 9 is inserted into the bottom end of the vent pipe 4, and the vent pipe 4 is inserted into the flange 16 connected to the top end of the sleeve 6; the vent pipe 4 is used to observe the evaporation rate of the refrigerant. If the exhaust volume of the vent increases significantly during the test and is accompanied by white steam, it indicates that the refrigerant is consumed violently, which can indicate the situation of helium vapor entering the test chamber to cool the sample, so as to obtain better temperature control accuracy and reduce the time required for the temperature controller to stabilize.

[0039] In this specific implementation manner, when a short sample of the superconducting material to be tested is subjected to a critical current test in an environment of different temperatures and different magnetic field strengths, the range of different temperatures is 4.2 to 80 K, and the range of different magnetic field strengths is 0 to 15 T. It should be noted that when the critical characteristics test sample rod of the present application is placed in a background magnet, the background magnetic field is provided by a superconducting spiral tube coil, and its inner and outer coils are respectively wound by Nb3Sn and NbT i wires.

[0040] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A sample rod for testing the critical characteristics of a short sample of a high-temperature superconducting material, characterized in that: The invention comprises a sleeve (6), a support mechanism and a current drainage circuit, wherein the bottom of the sleeve (6) is detachably connected to the support mechanism, the support mechanism is slidably connected to a constant temperature cover (9), the sleeve (6) is provided with a lifting mechanism connected to the constant temperature cover (9), and the constant temperature cover (9) is driven to move up and down along the height direction of the support mechanism by the lifting mechanism, the bottom of the support mechanism is provided with a sample rack, a heater is arranged in the sample rack, a short sample of a superconducting material to be tested is welded and fixed on the sample rack, and the short sample of the superconducting material to be tested is electrically connected through the current drainage circuit; When the support mechanism is placed in a refrigerant environment, a background magnet is arranged outside the short sample of the superconducting material to be tested, and the constant temperature cover (9) is driven downward by the lifting mechanism to form a test chamber for the short sample of the superconducting material to be tested, and the temperature in the test chamber is changed by adjusting the heater, so that the short sample of the superconducting material to be tested can be tested for critical current in environments with different temperatures and different magnetic field strengths.

2. The critical characteristics test sample rod of a short sample of a high-temperature superconducting material according to claim 1, characterized in that: The supporting mechanism comprises an upper insulating partition (17) and a lower insulating partition (12), wherein the upper insulating partition (17) is connected to the bottom end of the sleeve (6) by bolts, and the lower insulating partition (12) is used to support and fix the sample rack, and the lower insulating partition (12) is fixedly installed on the lower end plate (11), and the upper insulating partition (17) and the lower insulating partition (12) are connected by a plurality of stainless steel supports (8), and a plurality of middle insulating partitions (7) are arranged on the stainless steel supports (8), and the stainless steel supports (8) are used to be arranged to slide against the side wall of the constant temperature cover (9).

3. The critical characteristics test sample rod of a short sample of a high-temperature superconducting material according to claim 2, characterized in that: The current diversion circuit comprises two upper current leads (5), two middle current leads (14) and two lower current leads (10); the upper current leads (5) are inserted and connected to a flange (16); the flange (16) is fixedly connected to the top end of the sleeve (6); the tail end of the upper current leads extends out of the sleeve (6) and is welded and fixed to the middle current leads (14); the middle current leads (14) are arranged along the height direction of the support mechanism and are welded and fixed to the lower current leads (10); the lower current leads (10) are welded and fixed to current contacts (13) provided on the sample holder; and the short sample of the superconducting material to be tested is welded and fixed to the current contacts (13) to form a test current loop of the short sample of the superconducting material to be tested.

4. The critical characteristics test sample rod of a short sample of a high-temperature superconducting material according to claim 3, characterized in that: The upper current lead (5) is a wire with a hollow structure, and a superconducting wire and a superconducting tape are welded in the inner cavity of the upper current lead.

5. The critical characteristics test sample rod of a short sample of a high-temperature superconducting material according to claim 3, characterized in that: The middle current lead (14) and the lower current lead (10) are both conductors of strip-shaped structures, and grooves are provided on the outer surfaces of the middle current lead (14) and the lower current lead (10), and superconducting tapes are welded in the grooves.

6. The critical characteristics test sample rod of a short sample of a high-temperature superconducting material according to claim 1, characterized in that: The sample rack is provided with two thermometers which are arranged horizontally flush with the short sample of the superconducting material to be tested. The thermometers are used to detect the test temperature of the short sample of the superconducting material to be tested in real time and feed back to the temperature controller, which is used to adjust the heating temperature of the heater.

7. The critical characteristics test sample rod of a short sample of a high-temperature superconducting material according to claim 1, characterized in that: The lifting mechanism comprises a pull rod (1) and a pull rod holder (2); the tail end of the pull rod (1) is fixedly connected to the constant temperature cover (9); the pull rod (1) is inserted and connected to the flange (16) at the top end of the sleeve (6); the insertion position of the pull rod (1) is kept fixed on the flange (16) by the pull rod holder (2).

8. The critical characteristics test sample rod of a short sample of a high-temperature superconducting material according to claim 1, characterized in that: The number of short samples of superconducting material to be tested is at least two, and the short samples of superconducting material to be tested are connected to a signal collection line, the signal collection line is arranged in a lower cable tube (15), the lower cable tube (15) is arranged along the height direction of the support mechanism, the top end of the lower cable tube (15) is connected to an upper cable tube (3) arranged in the sleeve (6), and the upper cable tube (3) is inserted and connected to a flange (16) at the top end of the sleeve (6).

9. The critical characteristics test sample rod of a short sample of a high-temperature superconducting material according to claim 1, characterized in that: The top end of the thermostatic cover (9) is inserted and connected to the bottom end of the ventilation pipe (4), and the ventilation pipe (4) is inserted and connected to the flange (16) at the top end of the sleeve (6).

10. The critical characteristics test sample rod of a short sample of a high-temperature superconducting material according to claim 1, characterized in that: When the short sample of the superconducting material to be tested is subjected to critical current testing in different temperature and different magnetic field strength environments, the different temperature ranges from 4.2 to 80K, and the different magnetic field strength ranges from 0 to 15T.

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