A critical current measuring device for a racetrack-shaped superconducting coil

Abstract

The present invention discloses a critical current measuring device for a racetrack-shaped superconducting coil, comprising a straight section fixing device, a pressure regulating device, a measuring installation base plate, a crimping current lead terminal, and a crimping voltage measuring line terminal; the straight section fixing device is used to fix the racetrack-shaped superconducting coil, and the pressure regulating device is installed on the straight section fixing device to adjust the radial stress of the racetrack-shaped superconducting coil; the crimping current lead terminal and the crimping voltage measuring line terminal are installed on the measuring installation base plate, one end of which is connected to the racetrack-shaped superconducting coil, and the other end is connected to a power supply, a voltmeter, and other equipment. The present invention avoids the loosening of the straight section of the racetrack-shaped superconducting coil due to electromagnetic force or vibration during the excitation and transportation process, thereby affecting the electromagnetic performance; at the same time, the present invention adopts the crimping lead terminal, which has the characteristics of safety and reliability, simple structure, and convenient operation, and can accurately measure the critical current, n value, magnetic field, and other parameters of the superconducting coil.

Description

Technical Field

[0001] The invention belongs to the field of superconducting coil testing, and in particular relates to a critical current measuring device for a racetrack-shaped superconducting coil. Background Art

[0002] Since the discovery of superconductivity in 1911, superconductors have attracted widespread attention around the world due to their zero resistance effect, Meissner effect and Josephson effect. Superconducting magnets made of superconducting wires have the advantages of strong magnetic fields and low losses, so superconducting wires are widely used to make superconducting magnets. The unique structure of the racetrack-shaped superconducting coil can generate a specific magnetic field configuration, so it is widely used in magnetic levitation, superconducting wind turbines, accelerators and other fields.

[0003] Superconductors have three critical parameters: critical current, critical magnetic field, and critical temperature. The three parameters restrict and influence each other. When any one of the three exceeds its critical value, the superconductor will quench and show resistance effect. After the superconducting wire is wound into a superconducting coil, the critical parameters will be different due to the different magnetic field and current density distribution at different positions in the coil. How to accurately measure the critical current of the superconducting coil is a key issue.

[0004] The four-lead method is generally used to measure the critical current of a superconducting coil, which measures the voltage and current of the superconducting coil. In the traditional four-lead method, the voltage measurement wire is generally welded on the superconducting coil, and the current lead is generally connected to the runway-shaped superconducting coil terminal through a clamp. This method is cumbersome to operate and has the risk of damaging the superconducting coil.

[0005] At the same time, the racetrack-shaped superconducting coil has more straight sections than the traditional round coil. After calculation, it is found that the straight sections of the racetrack coil cannot exert radial stress during the coil winding process. Therefore, during the measurement and transportation of the racetrack coil, the straight sections of the racetrack coil are likely to become loose due to electromagnetic force or vibration, affecting the electromagnetic performance of the superconducting coil. Summary of the invention

[0006] In order to overcome the above technical problems, the present invention provides a critical current measuring device for a racetrack-shaped superconducting coil, which can conveniently, quickly and accurately measure the critical current of the superconducting coil, and can tighten the straight section of the racetrack-shaped superconducting coil without damaging the superconducting tape, thereby avoiding damage to the superconducting coil.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A critical current measuring device for a racetrack-shaped superconducting coil comprises a straight section fixing device, a pressure regulating device, a measuring mounting base plate, a crimping current lead terminal, a crimping voltage measuring line terminal and a magnetic field probe;

[0009] The straight segment fixing device is installed in the center above the measurement installation base plate, and includes an upper cover plate, a base plate, and an auxiliary gasket; the upper cover plate and the base plate are fixed by screws close to both sides; the inner surface of the upper cover plate and the base plate fits the outer surface of the racetrack-shaped superconducting coil; threaded holes are provided on the side walls on both sides of the base plate for installing a pressure regulating device; the pressure regulating device plays a role in regulating the radial stress of the racetrack-shaped superconducting coil;

[0010] The crimped current lead terminal and the crimped voltage measurement line terminal are installed at the four corners above the measurement installation base plate; the crimped current lead terminal includes a multifunctional wiring terminal and a current lead pressing piece; the current lead pressing piece is installed in the middle of the multifunctional wiring terminal; the crimped voltage measurement line terminal includes a multifunctional wiring terminal and a rotary voltage measurement piece; the rotary voltage measurement piece is installed on the side wall of the multifunctional wiring terminal.

[0011] Furthermore, an auxiliary gasket is installed between the side wall of the bottom plate and the side wall of the superconducting coil. One side of the auxiliary gasket is in contact with the end of the pressure regulating device, and the other side is in contact with the straight section of the racetrack-shaped superconducting coil, so as to avoid direct contact between the pressure regulating device and the surface of the racetrack-shaped superconducting coil, thereby preventing stress concentration.

[0012] Furthermore, a magnetic field probe installation hole is provided at the center of the upper cover plate for installing the magnetic field probe; observation holes are provided near both sides of the upper cover plate for observing the fastening condition of the straight section of the racetrack-shaped superconducting coil.

[0013] Furthermore, the upper cover plate and the bottom plate are made of aluminum alloy, and the inner surface is sprayed with polytetrafluoroethylene film; the auxiliary gasket and the measurement installation bottom plate are made of epoxy resin; and the pressure regulating device is made of low-temperature resistant non-magnetic metal material.

[0014] Furthermore, the current lead pressing piece is made of a highly elastic conductive material; and the rotary voltage measuring piece is made of a highly elastic conductive material.

[0015] Furthermore, a wiring hole is provided above the multifunctional terminal block for connecting a current lead or a voltage measurement line; the bottom of the multifunctional terminal block is cylindrical, which cooperates with the mounting holes at the four corners of the measuring base plate for easy installation, and the multifunctional terminal block is made of brass material.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The critical current measuring device of the racetrack-shaped superconducting coil designed by the present invention avoids the loosening of the straight section of the racetrack coil due to electromagnetic force or vibration during the excitation and transportation process of the racetrack coil, thereby affecting the electromagnetic performance of the superconducting coil;

[0018] (2) The critical current measuring device of the racetrack-shaped superconducting coil designed by the present invention has a simple design structure. The radial stress of the racetrack-shaped superconducting coil can be adjusted conveniently and quickly by adjusting the pressure regulating device. At the same time, the compression condition of the straight section can be observed at any time through the observation hole, which is safe and reliable.

[0019] (3) The critical current measuring device of the racetrack-shaped superconducting coil designed by the present invention avoids direct contact between the current lead and the voltage measuring wire and the superconducting coil. Compared with the traditional measurement method, it is safe and reliable, simple in structure and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 1 is a schematic structural diagram of a critical current measuring device for a racetrack-shaped superconducting coil according to an embodiment of the present invention;

[0021] Figure 2 is a schematic diagram of assembling a straight segment fastening device of a racetrack-shaped superconducting coil according to an embodiment of the present invention;

[0022] Figure 3 1 is a circuit diagram of a four-lead method for measuring critical current of a superconducting coil according to an embodiment of the present invention;

[0023] Figure 4 is a schematic structural diagram of a crimping current lead terminal according to an embodiment of the present invention;

[0024] Figure 5 is a schematic structural diagram of a crimping type voltage measurement line terminal according to an embodiment of the present invention;

[0025] Figure 6 is a graph showing the test results of the current, voltage and magnetic field of a superconducting coil of another preferred embodiment of the present invention;

[0026] Figure 7 It is a test result diagram of critical current and n value of a superconducting coil according to another preferred embodiment of the present invention.

[0027] In the figure: 1-racetrack-shaped superconducting coil; 2-straight segment fixing device; 3-pressure regulating device; 4-measuring installation base plate; 5-crimped current lead terminal; 6-crimped voltage measurement line terminal; 7-magnetic field probe; 8-multi-function terminal; 201-upper cover plate; 202-bottom plate; 203-auxiliary gasket; 204-magnetic field probe installation hole; 205-observation hole; 501-current lead pressing piece; 601-rotating voltage measurement piece; 801-wiring hole. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0029] In the drawings, components with the same structure are indicated by the same numerical reference numerals, and components with similar structures or functions are indicated by similar numerical reference numerals. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, the thickness of the components is appropriately exaggerated in some places in the drawings.

[0030] like Figure 1 As shown, the critical current measuring device of the racetrack-shaped superconducting coil of the embodiment of the present invention comprises a racetrack-shaped superconducting coil 1, a straight section fixing device 2, a pressure regulating device 3, a measuring installation base plate 4, a crimping current lead terminal 5, a crimping voltage measuring line terminal 6 and a magnetic field probe 7. The racetrack-shaped superconducting coil 1 is located inside the straight section fixing device 2, and the inner surface of the straight section fixing device 2 is in contact with the outer surface of the racetrack-shaped superconducting coil 1; the racetrack-shaped superconducting coil 1 and the straight section fixing device 2 are installed at the center of the measuring installation base plate 4; the crimping current lead terminal 5 and the crimping voltage measuring line terminal 6 are installed at the four corners of the measuring installation base plate 4 by screws; the magnetic field probe 7 is installed at the center of the racetrack-shaped superconducting coil 1 for measuring the magnetic field generated by the superconducting coil.

[0031] The critical current measuring device of the embodiment of the present invention can not only measure the critical current of the racetrack-shaped superconducting coil, but also measure the magnetic field, voltage, current, critical current, n value, time constant and other parameters in the excitation process of superconducting coils of other shapes. Figure 1 The racetrack-shaped superconducting coil 1, the straight segment fixing device 2, and the pressure regulating device 3 shown are removed and replaced with superconducting coils of other shapes.

[0032] like Figure 2The assembly diagram of the straight section fastening device of the racetrack-shaped superconducting coil of the embodiment of the present invention shown in the figure includes a racetrack-shaped superconducting coil 1, a pressure regulating device 3, an upper cover plate 201, a bottom plate 202, an auxiliary gasket 203, a magnetic field probe mounting hole 204 and an observation hole 205. The upper cover plate 201 is designed to be in a "convex" shape, and the upper surface of the racetrack-shaped superconducting coil 1 is in contact with the inner wall of the upper cover plate 201; the bottom plate 202 is designed to be in a "concave" shape, and the lower surface of the racetrack-shaped superconducting coil 1 is in contact with the inner wall of the bottom plate 202; the upper cover plate 201 and the bottom plate 202 are fixed by low-temperature resistant non-magnetic screws, and the upper cover plate 201, the bottom plate 202 and the racetrack-shaped superconducting coil 1 are positioned by positioning holes.

[0033] The pressure of the straight segment fixing device 2 of the racetrack-shaped superconducting coil of the present invention is adjustable, the side wall of the bottom plate 202 is provided with a threaded hole, and the pressure regulating device 3 is installed in the threaded hole of the side wall of the bottom plate 202; there is a gap between the inner surface of the side wall of the bottom plate 202 and the racetrack-shaped superconducting coil 1, and the auxiliary gasket 203 is installed in the gap; one side of the auxiliary gasket 203 is in contact with the end of the pressure regulating device 3, and the other side is in contact with the straight segment of the racetrack-shaped superconducting coil 1. The degree of contact between the auxiliary gasket 203 and the straight segment of the racetrack-shaped superconducting coil 1 is adjusted by adjusting the tightness of the pressure regulating device 3, so as to achieve the purpose of pressure regulation and straight segment tightening, which is convenient and fast. The observation holes 205 are provided near the edge parts on both sides of the upper cover plate 201, and the tightening condition of the straight segment of the superconducting coil 1 can be observed through the observation holes 205, which is safe and reliable.

[0034] The upper cover plate 201 and the bottom plate 202 are made of aluminum alloy or stainless steel, and the inner surfaces are sprayed with polytetrafluoroethylene film to ensure that the inner surfaces of the upper cover plate 201 and the bottom plate 202 that contact the superconducting coil 1 are non-conductive.

[0035] A magnetic field probe mounting hole 204 is provided at the center of the upper cover plate 201 and the center of the superconducting coil. The magnetic field probe 7 can be installed in the magnetic field probe mounting hole 204 by vacuum sealing.

[0036] The auxiliary gasket 203 is generally made of epoxy resin, which has the advantages of lightness, high mechanical strength, good heat resistance, etc. For the racetrack-shaped double-pancake superconducting coil, the auxiliary gasket 203 is generally set in a "concave" shape to leave space for the insulating baffle between the double pancakes of the racetrack coil.

[0037] The measuring and mounting base plate 4 is made of epoxy resin material.

[0038] like Figure 3The circuit diagram of the four-lead method for measuring the critical current of a superconducting coil according to an embodiment of the present invention is shown. The circuit mainly includes four parts: a power supply, an ammeter, a voltmeter, and a superconducting coil. The crimped current lead terminal 5 is used to connect the power supply, the voltmeter and the superconducting coil, and the crimped current measurement wire terminal 6 is used to connect the voltmeter and the superconducting coil.

[0039] like Figure 4 , Figure 5 As shown, the crimped current lead terminal 5 and the crimped voltage measurement line terminal 6 are both fixed by a multifunctional wiring terminal 8. The multifunctional wiring terminal 8 is provided with a wiring hole 801 on the upper part for connecting the current lead or the voltage measurement line, thereby avoiding direct contact between the current lead and the voltage measurement line and the superconducting coil, thereby causing damage to the superconducting coil. The bottom of the multifunctional wiring terminal 8 is set in a cylindrical shape, which cooperates with the installation holes at the four corners of the measurement installation base plate 4, and is convenient and quick to install.

[0040] A current lead pressing piece 501 is arranged at the center of the crimped current lead terminal 5. The current lead pressing piece 501 is generally made of a highly elastic conductive material. The superconducting coil terminal is fixed by the current lead pressing piece 501, which is firmly fitted and easy to operate.

[0041] A rotating voltage measuring piece 601 is provided on the side of the crimping voltage measuring line terminal 6. The rotating voltage measuring piece 601 is generally made of a highly elastic conductive material. By adjusting the angle of the rotating voltage measuring piece 601, it can be completely fitted with the side of the superconducting coil. The operation is simple and easy to adjust.

[0042] like Figure 6 The test results of the current, voltage and magnetic field of the superconducting coil of another preferred embodiment are shown in FIG. The device of the present invention can accurately measure the voltage, current and magnetic field of the superconducting coil during the excitation process, which is convenient and reliable.

[0043] like Figure 7 The test result diagram of critical current and n value of the superconducting coil of another preferred embodiment is shown. By measuring the voltage and current during the excitation process and using software to perform curve fitting, the critical current and n value of the superconducting coil can be calculated, which is convenient and quick.

[0044] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A critical current measuring device for a racetrack-shaped superconducting coil, characterized in that: It comprises a straight section fixing device (2), a pressure regulating device (3), a measuring installation base plate (4), a crimping current lead terminal (5), a crimping voltage measuring line terminal (6) and a magnetic field probe (7); The straight segment fixing device (2) is installed at the center above the measuring installation base plate (4), and comprises an upper cover plate (201), a base plate (202), and an auxiliary gasket (203); the upper cover plate (201) and the base plate (202) are fixed by screws close to both sides; the inner surfaces of the upper cover plate (201) and the base plate (202) are in contact with the outer surface of the racetrack-shaped superconducting coil (1); threaded holes are provided on the side walls of both sides of the base plate (202) for installing a pressure regulating device (3); the pressure regulating device (3) serves to regulate the radial stress of the racetrack-shaped superconducting coil (1); The crimped current lead terminal (5) and the crimped voltage measurement line terminal (6) are installed at four corners above the measurement installation base plate (4); the crimped current lead terminal (5) comprises a multifunctional wiring terminal (8) and a current lead pressing piece (501); the current lead pressing piece (501) is installed in the middle of the multifunctional wiring terminal (8); the crimped voltage measurement line terminal (6) comprises a multifunctional wiring terminal (8) and a rotary voltage measurement piece (601); the rotary voltage measurement piece (601) is installed on the side wall of the multifunctional wiring terminal (8).

2. The critical current measuring device of a racetrack-shaped superconducting coil according to claim 1, characterized in that: An auxiliary gasket (203) is installed between the side wall of the bottom plate (202) and the side wall of the racetrack-shaped superconducting coil (1); one side of the auxiliary gasket (203) is in contact with the end of the pressure regulating device (3), and the other side is in contact with the straight section of the racetrack-shaped superconducting coil (1), so as to avoid direct contact between the pressure regulating device (3) and the surface of the racetrack-shaped superconducting coil (1), thereby preventing stress concentration.

3. The critical current measuring device of a racetrack-shaped superconducting coil according to claim 1, characterized in that: A magnetic field probe mounting hole (204) is provided at the center of the upper cover plate (201) for mounting a magnetic field probe (7); observation holes (205) are provided near two sides of the upper cover plate (201) for observing the tightening condition of the straight section of the racetrack-shaped superconducting coil (1).

4. The critical current measuring device of a racetrack-shaped superconducting coil according to claim 1, characterized in that: The upper cover plate (201) and the bottom plate (202) are made of aluminum alloy, and the inner surfaces are sprayed with a polytetrafluoroethylene film; the auxiliary gasket (203) is made of epoxy resin; and the pressure regulating device (3) is made of a low-temperature resistant non-magnetic metal material.

5. The critical current measuring device of a racetrack-shaped superconducting coil according to claim 1, characterized in that: The current lead pressing sheet (501) is made of a highly elastic conductive material; and the rotary voltage measuring sheet (601) is made of a highly elastic conductive material.

6. The critical current measuring device of a racetrack-shaped superconducting coil according to claim 1, characterized in that: The multifunctional wiring terminal (8) is provided with a wiring hole (801) above for connecting a current lead or a voltage measurement line; the bottom of the multifunctional wiring terminal (8) is cylindrical and cooperates with the mounting holes at the four corners of the measurement installation base plate (4) for easy installation; the multifunctional wiring terminal (8) is made of brass material.

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