An apparatus and method for testing critical current of superconducting tapes

Abstract

The application relates to a device and method for testing critical current of superconducting strips, comprising a fixing unit, a magnetic field generating unit and a measuring unit, wherein the fixing unit comprises a first clamping part and a second clamping part for tensioning the superconducting strip to be tested; the magnetic field generating unit comprises two magnets with the same magnetic field intensity, and the superconducting strip to be tested is arranged between the two poles of the two magnets; the measuring unit comprises a current input unit and a voltage measuring unit, the current input unit comprises a current lead and a current pole connecting unit, the current pole connecting unit is provided with an insulating layer, the current lead is connected with the current pole connecting unit, and the voltage lead is connected with the superconducting strip to be tested; when the superconducting strip to be tested is tested, the insulating layer is pressed on the superconducting strip to be tested. The application can avoid the burning of the superconducting strip caused by the local heat accumulation of the superconducting strip due to the contact between the current pole and the superconducting strip to be tested during the testing process.

Description

Technical Field

[0001] This invention relates to the field of superconducting material performance testing technology, and in particular to an apparatus and method for testing the critical current of superconducting tapes. Background Technology

[0002] Since its discovery in 1911, superconductivity has been a crucial area of ​​research in physics. The reason superconductivity has garnered worldwide attention is its irreplaceable technological applications, its broad prospects for growth, and its significant economic benefits. Currently, applications of superconductivity extend to electrical engineering, power, transportation, energy, medicine, high-energy physics, and the military.

[0003] With the promotion and application of superconducting tapes, the quality requirements for superconducting tapes are becoming increasingly stringent. Among these requirements, the critical current of the superconducting tape is a key factor in evaluating its quality. Currently, there are two main methods for testing the critical current of superconducting tapes: magnetic measurement and electrical measurement. The magnetic measurement method has the advantage of being non-contact and causing minimal damage to the tape, and it can be used for continuous measurement of long superconducting tapes. However, its limitation is that it cannot directly measure the critical current of the superconducting tape, resulting in a certain degree of error and often failing to obtain the true critical current value. The electrical measurement method can directly measure the critical current of the superconducting tape. However, during the testing process, the current needs to be in direct contact with the superconducting tape. Poor contact or an excessively small contact area can lead to excessively high contact resistance, causing the superconducting tape to burn out due to localized heat accumulation during the test. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a device for testing the critical current of superconducting tapes, which can accurately measure the critical current of superconducting tapes of different widths and can avoid the superconducting tapes from burning out due to local heat accumulation during the testing process.

[0005] To solve the above-mentioned technical problems, the present invention provides a device for testing the critical current of superconducting tapes, characterized in that it includes:

[0006] The fixing unit includes a first clamping part and a second clamping part, which clamp the superconducting tape to be tested.

[0007] A magnetic field generating unit includes two magnets with the same magnetic field strength, and the superconducting material to be tested is disposed between the opposite poles of the two magnets;

[0008] The measurement unit includes a current input unit and a voltage measurement unit. The current input unit includes a current lead and a current electrode connection unit. The current electrode connection unit is provided with an insulating layer. The current lead is connected to the current electrode connection unit. The voltage measurement unit includes a voltage lead. The voltage lead is connected to the superconducting tape under test and collects the potential difference of the superconducting tape under test. When testing the superconducting tape under test, the insulating layer is pressed onto the superconducting tape under test.

[0009] Preferably, the current electrode connection unit includes a first current electrode connection unit and a second current electrode connection unit respectively disposed at both ends of the magnetic field generating unit.

[0010] Preferably, the current lead is soldered onto the current electrode connection unit.

[0011] Preferably, the voltage lead is welded onto the superconducting tape to be tested.

[0012] Preferably, one end of the voltage lead is connected to the superconducting tape under test located between the magnet generating unit and the first current electrode connecting unit, and the other end is connected to the superconducting tape under test located between the magnet generating unit and the second current electrode connecting unit.

[0013] Preferably, the current electrode connection unit is plated with an insulating layer.

[0014] Preferably, the insulating layer is an oxide insulating layer, and the thickness of the oxide insulating layer is 0.1-0.3 mm.

[0015] Preferably, the voltage measuring unit includes a voltmeter, and the voltage lead is connected to the voltmeter.

[0016] Preferably, the current input unit includes a current source, and the current lead is connected to the current source.

[0017] On the other hand, the present invention also provides a method for testing the critical current of a superconducting tape, which utilizes the apparatus for testing the critical current of a superconducting tape as described above to test the superconducting tape under test, and includes the following steps.

[0018] Step S1: Fix both ends of the superconducting tape to be tested and place the superconducting tape to be tested in a test environment with a magnetic field;

[0019] Step S2: Apply current to the superconducting tape under test and collect the potential difference;

[0020] Step S3: Obtain the UI curve based on the potential difference and current, and calculate the critical current value.

[0021] The technical solution of the present invention has the following advantages compared with the prior art:

[0022] This invention discloses a device for testing the critical current of superconducting tapes. The device uses a fixing unit to fix the superconducting tape under test and a magnetic field generating unit to place the tape in a magnetic field environment. A measuring unit collects current and voltage data flowing through the tape to obtain its critical current value. This device is widely applicable to various types of superconducting tapes and can accurately measure the critical current of tapes of different widths. Utilizing Josephson's zero-voltage supercurrent effect, it avoids the burning of the superconducting tape due to localized heat accumulation caused by contact between the current electrode and the tape during testing. The device is simple in structure, low in cost, and easy to operate, providing a simple and direct way to obtain the critical current value of the superconducting tape. Attached Figure Description

[0023] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0024] Figure 1 This is a schematic diagram of the structure of the preferred embodiment of the present invention.

[0025] Figure 2 This is a cross-sectional structural schematic diagram of the magnet generating unit according to the preferred embodiment of the present invention.

[0026] Explanation of reference numerals in the accompanying drawings: 1-Superconducting tape to be tested, 2-Magnet generating unit, 21-First magnet, 22-Second magnet, 3-Current lead, 4-Current electrode connection unit, 41-Insulating layer, 5-Voltage lead, 6-Current source, 7-Voltmeter. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0028] Example

[0029] Reference Figure 1 and Figure 2 As shown, this invention discloses an apparatus for testing the critical current of superconducting tapes, comprising:

[0030] The fixing unit includes a first clamping part and a second clamping part. The first clamping part and the second clamping part clamp the end of the superconducting tape 1 to be tested, tighten the superconducting tape 1 to be tested, generate tension inside the superconducting tape 1 to be tested, and keep it straight.

[0031] The magnetic field generating unit 2 includes two magnets with the same magnetic field strength. A portion of the superconducting material 1 to be tested is disposed between the opposite poles of the two magnets. Specifically, the magnetic field generating unit includes a support 20, a first magnet 21, and a second magnet 22. The first magnet 21 and the second magnet 22 are placed on the support 20, and the magnetic field directions of the first magnetic field 21 and the second magnetic field 22 are opposite, so that the S pole of one magnet and the N pole of the other magnet are opposite. The superconducting tape 1 to be tested passes between the S pole and the N pole without contacting either magnet, so that the superconducting tape 1 to be tested can be in a magnetic field environment of a certain strength.

[0032] The measurement unit includes a current input unit and a voltage measurement unit. The current input unit includes a current lead 3 and a current electrode connection unit 4. The current electrode connection unit has an insulating layer 41. The current lead 3 is connected to the current electrode connection unit 4. The voltage measurement unit includes a voltage lead 5, which is connected to the superconducting tape 1 under test and collects the potential difference of the superconducting tape 1 under test. When testing the superconducting tape 1 under test, the insulating layer 41 is pressed onto the superconducting tape 1 under test. The current electrode connection unit 4 is made of a material with superconducting properties.

[0033] The testing principle of this invention is as follows: the critical current of a superconducting tape is negatively correlated with the magnitude of the applied magnetic field; the stronger the applied magnetic field, the smaller the critical current of the superconducting tape. In this invention, the purpose of setting up the magnetic field generating unit 2 is to use the magnetic field to reduce the critical current of the superconducting tape 1 under test, thereby achieving the conditions for realizing a Josephson junction. The insulating layer 41 is pressed onto the superconducting tape 1 under test. At this time, the current electrode connecting unit 4, the insulating layer 41, and the superconducting tape 1 under test form a Josephson tunnel junction. When the critical current of the Josephson tunnel junction is greater than the critical current of the superconducting tape 1 under test, the Josephson effect will occur. Utilizing the zero-voltage supercurrent phenomenon of the Josephson effect, the current applied by the current source can pass through the superconducting tape under test without heat accumulation, thereby preventing the superconducting tape under test from burning out.

[0034] Therefore, the device for testing the critical current of superconducting tapes described in this invention uses a fixing unit to fix the superconducting tape under test and a magnetic field generating unit to place the superconducting tape under test in a magnetic field environment. The measuring unit collects the current and voltage data flowing through the superconducting tape under test and calculates its critical current value. This device for testing the critical current of superconducting tapes is widely applicable to various types of superconducting tapes and can accurately measure the critical current of superconducting tapes of different widths. Utilizing Josephson's zero-voltage supercurrent effect, it avoids the superconducting tape burning caused by localized heat accumulation due to contact between the current electrode and the superconducting tape under test during testing. This invention has a simple structure, low cost, and convenient operation, and can easily and directly obtain the critical current value of superconducting tapes.

[0035] Furthermore, the current electrode connection unit 4 includes a first current electrode connection unit and a second current electrode connection unit respectively disposed on both sides of the magnetic field generating unit.

[0036] Furthermore, the current lead 3 is welded to the current electrode connection unit 4. The voltage lead 5 is welded to the superconducting tape 1 under test. In detail, one end of the voltage lead 5 is welded to the superconducting tape 1 under test between the magnet generating unit 2 and the first current electrode connection unit, and the other end is welded to the superconducting tape 1 under test between the magnet generating unit 2 and the second current electrode connection unit.

[0037] Specifically, the current electrode connection unit 4 is plated with an insulating layer, which is an oxide insulating layer. In this embodiment, the insulating layer is made of yttrium trioxide, also known as yttrium oxide, with the chemical formula Y2O3 and a thickness of 0.1-0.3 mm.

[0038] In detail, the voltage measurement unit includes a voltage meter 7, and the voltage lead 5 is connected to the voltage meter 7. The current input unit includes a current source 6, and the current lead 3 is connected to the current source 6, which provides current to the superconducting tape 1 under test.

[0039] The testing device is connected to an external computer software terminal, which can collect the potential difference and the input current value to obtain the UI curve, and then calculate the critical current value through the computer software.

[0040] On the other hand, the present invention also discloses a method for testing the critical current of a superconducting tape, which utilizes the apparatus for testing the critical current of a superconducting tape as described above to test the superconducting tape under test, and includes the following steps.

[0041] Step S1: Fix both ends of the superconducting tape 1 to be tested, and place the superconducting tape to be tested in a test environment with a magnetic field;

[0042] Step S2: Apply current to the superconducting tape 1 to be tested and collect the potential difference;

[0043] Step S3: Obtain the UI curve based on the potential difference and calculate the critical current value.

[0044] Specifically, step S1 includes:

[0045] Step S11: Place two magnets with the same magnetic field strength on the support 20 with a gap between them, so that the N poles and S poles of the two magnets are facing each other;

[0046] Step S12: Fix both ends of the superconducting tape 1 to be tested on the first clamping part and the second clamping part respectively, pull the superconducting tape 1 to be tested tight to keep it straight, and make the superconducting tape 1 to be tested pass between the N pole and S pole of the two magnets without contacting either magnet.

[0047] Furthermore, S2 includes:

[0048] S21: An insulating layer 41 is plated on the current electrode connection unit 4, the insulating layer 41 on the current electrode connection unit 4 is pressed onto the superconducting tape 1 to be tested, the current lead 3 is welded to the current electrode connection unit 4, the voltage lead 5 is welded to the superconducting tape 1 to be tested, current is applied to the superconducting tape 1 to be tested through the current source 6, and the potential difference is collected.

[0049] In detail, S3 includes:

[0050] S31: Based on the collected potential difference and the applied current value, the UI curve is obtained, and the critical current value of the superconducting tape 1 to be tested is calculated by computer software.

[0051] In summary, the device for testing the critical current of superconducting tapes described in this invention uses a fixing unit to fix the superconducting tape under test and a magnetic field generating unit to place the superconducting tape under test in a magnetic field environment. A measuring unit collects current and voltage data flowing through the superconducting tape under test, and the critical current value is calculated. The device and method for testing the critical current of superconducting tapes described in this invention are widely applicable to various types of superconducting tapes and can accurately measure the critical current of superconducting tapes of different widths. Utilizing Josephson's zero-voltage supercurrent effect, it avoids the superconducting tape burning due to localized heat accumulation caused by contact between the current electrode and the superconducting tape under test during testing. The testing device of this invention has a simple structure, low cost, and convenient operation, and can easily and directly obtain the critical current value of superconducting tapes.

[0052] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A device for testing the critical current of superconducting tapes, characterized in that: include, The fixing unit includes a first clamping part and a second clamping part, which clamp the superconducting tape to be tested. A magnetic field generating unit includes two magnets with the same magnetic field strength, and the superconducting tape to be tested is disposed between the two opposite poles of the two magnets; The measurement unit includes a current input unit and a voltage measurement unit. The current input unit includes a current lead and a current electrode connection unit. The current electrode connection unit is provided with an insulating layer. The current lead is connected to the current electrode connection unit. The voltage measurement unit includes a voltage lead. The voltage lead is connected to the superconducting tape under test and collects the potential difference of the superconducting tape under test. When testing the superconducting tape under test, the insulating layer is pressed onto the superconducting tape under test. The current electrode connection unit includes a first current electrode connection unit and a second current electrode connection unit respectively disposed at both ends of the magnetic field generating unit. One end of the voltage lead is connected to the superconducting tape under test located between the magnetic field generating unit and the first current electrode connecting unit, and the other end is connected to the superconducting tape under test located between the magnetic field generating unit and the second current electrode connecting unit. The current electrode connection unit, the insulating layer, and the superconducting tape under test form a Josephson tunnel junction. When the critical current of the Josephson tunnel junction is greater than the critical current of the superconducting tape under test, the Josephson effect is generated. The zero-voltage supercurrent phenomenon of the Josephson effect is utilized to allow the current to pass through the superconducting tape under test without heat accumulation.

2. The apparatus for testing the critical current of superconducting tapes according to claim 1, characterized in that: The current lead is soldered onto the current electrode connection unit.

3. The apparatus for testing the critical current of superconducting tapes according to claim 1, characterized in that: The voltage lead is welded onto the superconducting tape to be tested.

4. The apparatus for testing the critical current of superconducting tapes according to claim 1, characterized in that: The current electrode connection unit is plated with an insulating layer.

5. The apparatus for testing the critical current of a superconducting tape according to claim 1, characterized in that: The insulating layer is an oxide insulating layer, and the thickness of the oxide insulating layer is 0.1-0.3 mm.

6. The apparatus for testing the critical current of a superconducting tape according to claim 1, characterized in that: The voltage measuring unit includes a voltmeter, and the voltage lead is connected to the voltmeter.

7. The apparatus for testing the critical current of a superconducting tape according to claim 1, characterized in that: The current input unit includes a current source, and the current lead is connected to the current source.

8. A method for testing the critical current of a superconducting tape, comprising testing the superconducting tape to be tested using the apparatus for testing the critical current of a superconducting tape as described in any one of claims 1-7, characterized in that: Includes the following steps, Step S1: Fix both ends of the superconducting tape to be tested and place the superconducting tape to be tested in a test environment with a magnetic field; Step S2: Apply current to the superconducting tape under test and collect the potential difference; Step S3: Obtain the UI curve based on the potential difference and current, and calculate the critical current value.

Images