A non-contact high-temperature superconducting tape critical current uniformity continuous non-destructive testing device and method

Abstract

The application discloses a kind of non-contact high-temperature superconducting tape critical current uniformity continuous nondestructive testing device and method, applied to superconducting material detection field, comprising: excitation magnet, for producing background magnetic field, excitation high-temperature superconducting tape generates magnetization current;Measuring probe, by magnetic circuit core, fluxgate sensor, copper band compensation loop is formed;Fluxgate sensor and copper band compensation loop are connected with control and measurement circuit respectively by fluxgate power supply acquisition line and copper band compensation loop power supply line;Control and measurement circuit, for when fluxgate sensor detects that net residual magnetic flux in magnetic circuit core is not 0, PID control is implemented by closed loop negative feedback, in copper band compensation loop, the magnetic flux that is equal to high-temperature superconducting tape, opposite, and according to current in copper band compensation loop when net residual magnetic flux is 0, calculate critical current.The application realizes the fast, accurate measurement of high-temperature superconducting tape critical current uniformity without depending on Hall sensor and without calibration inverse calculation.

Description

Technical Field

[0001] This invention relates to the field of superconducting material testing technology, and more specifically to a non-contact, continuous, non-destructive testing device and method for the critical current uniformity of high-temperature superconducting tapes. Background Technology

[0002] Superconducting materials, due to their zero-resistance characteristics and ability to withstand strong magnetic fields, hold an irreplaceable core position in high-end equipment such as fusion reactors, particle accelerators, strong-field magnets, and superconducting motors. Among them, high-temperature superconducting tapes, represented by copper oxide superconductors, have become the most important superconducting materials in engineering applications. Superconducting tapes often operate in extreme low-temperature (4.2-77K), strong magnetic field (>20T), and complex cyclic loading environments. As a key component of superconducting equipment, the uniformity of the critical current (Ic) of the superconducting tape directly determines the electromagnetic performance and safety threshold of the equipment. However, the crystal structure of high-temperature superconducting tapes themselves makes them highly susceptible to local defects during material production and equipment assembly, causing a decrease in the local critical current. This will greatly threaten the reliability and stability of superconducting equipment. Therefore, it is necessary to continuously measure the critical current uniformity of high-temperature superconducting long tapes used in the manufacture of superconducting equipment to ensure that the critical current of the superconducting tape meets the requirements of equipment manufacturing both overall and locally.

[0003] Existing methods for measuring the critical current of high-temperature superconducting tapes can be divided into contact and non-contact methods. The contact method is represented by the "four-lead method." This method injects a stepped DC current into the superconducting tape and monitors the voltage change. When the voltage drop per unit length of the tape reaches 1 μV / cm, the corresponding current value is the critical current. This method requires direct contact with the tape, which easily introduces contact resistance, causing local overheating or even damage to the tape. Furthermore, it has low measurement efficiency and is difficult to achieve continuous and rapid measurement of long tapes (hundreds of meters in length). Non-contact measurement methods mainly utilize magnetic signal measurement. By detecting the response of the superconducting tape to a magnetic field, its critical current is calculated. Therefore, non-contact measurement methods can achieve continuous and non-destructive testing of the tape.

[0004] However, existing non-contact measurement methods generally suffer from low accuracy. For example, the widely used Hall probe method calculates the magnetization critical current by measuring the distribution of the residual magnetic field after magnetization of a superconducting tape. This method is extremely sensitive to the relative position of the tape and the probe; a shift of a hundred micrometers can lead to an error of more than 15% in the measurement results. The measurer cannot distinguish whether the change in reading is due to positional shift or a change in the tape's inherent properties. Another example is the magnetic circuit method, which improves upon the Hall probe method by reading the residual magnetic field strength instead of the magnetic field distribution, reducing the dependence of the measurement results on probe positioning. However, because it still relies on the Hall sensor to measure the magnetic field, the background noise from the sensor itself is typically in the range of 3-5 amperes. Furthermore, the residual magnetization current within the tape is difficult to calculate quantitatively, requiring individual calibration for each sample, increasing the complexity of the measurement results. Moreover, Hall sensor elements, especially low-temperature Hall sensor elements that can operate below the superconducting critical temperature, inherently suffer from limited accuracy, low operational stability, dependence on specific suppliers, and high cost.

[0005] Therefore, how to provide a non-contact, continuous, non-destructive testing device and method for measuring the critical current uniformity of high-temperature superconducting tapes without relying on Hall sensors and achieving rapid and accurate measurement is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a non-contact, continuous, and non-destructive testing device and method for the critical current uniformity of high-temperature superconducting tapes. It can achieve non-contact, continuous, and rapid testing of the critical current uniformity of high-temperature superconducting tapes without additional calibration. Moreover, the present invention does not require the use of Hall sensors, thus reducing the manufacturing cost of the measurement probe.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A non-contact, continuous, non-destructive testing device for the critical current uniformity of high-temperature superconducting tapes includes: an excitation magnet, a measuring probe, a control and measuring circuit, a constant temperature container, and a transmission mechanism. Excitation magnets are used to generate a background magnetic field and to excite the high-temperature superconducting tape to generate a magnetizing current. The measuring probe consists of a magnetic circuit core, a fluxgate sensor, and a copper strip compensation circuit. The fluxgate sensor and the copper strip compensation circuit are connected to the control and measurement circuits through the fluxgate power acquisition line and the copper strip compensation circuit power supply line, respectively. Fluxgate sensor is used to detect the net residual magnetic flux in the core of a magnetic circuit; The control and measurement circuit is used to implement PID control through closed-loop negative feedback logic when the net residual magnetic flux is not zero, generate a magnetic flux in the copper strip compensation circuit that is the same size and opposite to that of the high-temperature superconducting strip, and calculate the critical current of the high-temperature superconducting strip based on the current in the copper strip compensation circuit when the net residual magnetic flux is zero. A constant temperature container is used to maintain a vacuum low temperature environment test zone, so that the high temperature superconducting tape is in a superconducting state and is kept at a preset temperature. The transmission mechanism is used to drive the high-temperature superconducting tape through the excitation magnet and the measuring probe in sequence, and to record the sample position at the measuring probe in real time, so as to measure the critical current of the high-temperature superconducting tape at each position.

[0008] Optionally, the excitation magnet is a pair of discrete energized coils, and the intensity of the background magnetic field is more than twice the intensity of the penetration field of the high-temperature superconducting tape.

[0009] Optionally, after passing through the background magnetic field generated by the excitation magnet, the high-temperature superconducting tape maintains a bidirectional annular magnetization current, and the annular magnetization current is maintained without decay, with a density equal to the critical current density of the high-temperature superconducting tape.

[0010] Optionally, the fluxgate sensor is composed of a high-permeability, low-saturation soft magnetic material core wound with an excitation coil and a acquisition coil.

[0011] Optionally, the copper strip compensation circuit has the same width as the high-temperature superconducting strip and is symmetrically arranged on the magnetic circuit core. It consists of two copper flat strips of equal width that are insulated from each other and are short-circuited at the ends.

[0012] Optional control and measurement circuitry includes: fluxgate drive circuit, fluxgate demodulation circuit, PID control module, and voltage-controlled current source; The fluxgate drive circuit is used to provide a high-frequency alternating current to the excitation coil, so that the high permeability, low saturation soft magnetic material core is periodically saturated in positive and negative directions, and the acquisition coil is used to read the magnetic flux signal in the high permeability, low saturation soft magnetic material core. The fluxgate demodulation circuit is used to demodulate the magnetic flux signal to obtain the net residual magnetic flux in the magnetic core. A voltage-controlled current source is used to supply power and current to the copper strip compensation circuit; The PID control module is used to implement PID control through closed-loop negative feedback logic when the net residual magnetic flux is not zero, thereby adjusting the current output of the voltage-controlled current source and generating a magnetic flux in the copper strip compensation circuit that is the same size as and opposite to that of the high-temperature superconducting strip.

[0013] Optional, the calculation method for the current in the copper strip compensation circuit is as follows: A resistor with a known resistance is connected in series in the power supply line of the copper strip compensation circuit. By measuring the voltage across the resistor, the current in the copper strip compensation circuit can be obtained according to Ohm's law.

[0014] Optionally, the critical current of the high-temperature superconducting tape can be calculated based on the current in the copper tape compensation circuit when the net remanent magnetic flux is 0. Specifically: When the net remanent flux is 0, the current in the copper strip compensation circuit is equivalent to half of the ring current in the high-temperature superconducting tape. Based on the closed-loop zero flux symmetry of the measuring probe, the critical current of the high-temperature superconducting tape is as follows:

[0015] in, This is the critical current for high-temperature superconducting tapes; This is for the current in the copper strip compensation circuit.

[0016] Optionally, the transmission mechanism includes: a pay-off reel, a take-up reel, a first guide pulley, and a second guide pulley; At the start of the measurement, the high-temperature superconducting tape is coiled on the pay-off reel, which rotates together with the take-up reel. Guided by the first and second guide pulleys, the tape maintains a preset tension, allowing it to pass sequentially through the excitation magnet and the measuring probe, and finally be collected by the take-up reel, thus completing the measurement of the critical current at various locations of the high-temperature superconducting tape.

[0017] This invention also provides a non-contact method for continuous non-destructive testing of the critical current uniformity of high-temperature superconducting tapes using a non-contact continuous non-destructive testing device, comprising: Step 1: After the high-temperature superconducting tape is lowered to the preset temperature in the constant-temperature container, the transmission mechanism drives the high-temperature superconducting tape through the excitation magnet and the measuring probe in sequence, and records the sample position at the measuring probe in real time; wherein, after the high-temperature superconducting tape passes through the background magnetic field generated by the excitation magnet, it maintains a bidirectional annular magnetization current; when the high-temperature superconducting tape passes through the magnetic circuit core, the net residual magnetic flux in the magnetic circuit core is detected by the fluxgate sensor; Step 2: When the fluxgate sensor detects that the net residual flux in the magnetic circuit core is not zero, the control and measurement circuit implements PID control through closed-loop negative feedback logic to generate a magnetic flux in the copper strip compensation circuit that is the same size as and opposite to that of the high-temperature superconducting strip. Step 3: Based on the sample position at the probe of the high-temperature superconducting tape, and according to the current in the copper tape compensation circuit when the net residual magnetic flux is 0, calculate the critical current of the high-temperature superconducting tape at each position.

[0018] As can be seen from the above technical solution, compared with the prior art, this invention discloses a non-contact, continuous, non-destructive testing device and method for the critical current uniformity of high-temperature superconducting tapes. By setting an excitation coil to generate a background magnetic field, this magnetic field can induce the generation of a magnetizing current in the high-temperature superconducting tape (the density of this magnetizing current can be regarded as the critical current density of the high-temperature superconducting tape). Simultaneously, a measurement probe based on the fluxgate closed-loop negative feedback principle is equipped to monitor the magnetizing current intensity. In specific operation, the fluxgate assembly first detects the non-zero signal in the magnetic circuit of the measurement probe, and then, through the closed-loop negative feedback mechanism, adjusts the current in the copper tape compensation circuit within the measurement probe, ultimately maintaining the magnetic circuit of the measurement probe in a zero-flux state. In this state, only a simple measurement of the current in the copper tape compensation circuit is needed, followed by a multiplier conversion, to obtain the critical current of the high-temperature superconducting tape at that location.

[0019] Compared with existing technologies, the core innovation of this invention lies in combining the closed-loop zero flux control principle with the fluxgate magnetic field measurement principle, and specifically setting up a copper strip compensation circuit with the same geometric parameters as the high-temperature superconducting tape to be measured. The magnetic flux generated by the magnetization current of the tape is canceled by the compensation circuit, achieving equivalent measurement. The specific advantages can be summarized in three points: First, there is no need to use a low-temperature Hall sensor, which significantly reduces the manufacturing cost of the sensor; second, the measurement signal of the fluxgate is only used for closed-loop control to achieve current equivalence, without relying on the accurate measurement of the absolute value of magnetic flux density to calculate the current. This avoids the limitation of sensor accuracy on the results in the measurement of the absolute value of magnetic field, and also solves the technical problem of calculating the current from the magnetic field, effectively improving the measurement accuracy of the critical current; third, the critical current of the superconducting tape can be obtained by directly converting the current of the copper strip compensation circuit, which greatly simplifies the measurement process and improves the ease of operation. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the device structure provided by the present invention.

[0022] Figure 2 This is a schematic diagram of the measurement probe structure provided by the present invention.

[0023] Figure 3 The schematic diagram of the control and measurement circuit provided by the present invention implements PID control through closed-loop negative feedback logic.

[0024] Among them, 1-excitation magnet, 2-measuring probe, 3-control and measurement circuit, 4-high temperature superconducting tape, 5-magnetic fluxgate sensor, 6-copper tape compensation circuit, 7-excitation coil, 8-acquisition coil, 9-magnetic fluxgate power supply acquisition line, 10-copper tape compensation circuit power supply line, 11-pay-out reel, 12-take-up reel, 13-first guide pulley, 14-second guide pulley. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1: Embodiment 1 of this invention discloses a non-contact, continuous, non-destructive testing device for the critical current uniformity of high-temperature superconducting tapes, such as... Figure 1 As shown, it includes: excitation magnet 1, measuring probe 2, control and measuring circuit 3, constant temperature container and transmission mechanism; Excitation magnet 1 is used to generate a background magnetic field and to excite the high-temperature superconducting tape 4 to generate a magnetizing current.

[0027] The excitation magnet 1 is a pair of discrete energized coils, and the intensity of the background magnetic field is higher than the penetration field intensity of the high-temperature superconducting tape 4. Twice that; generally, an electric field strength higher than 1.2T is sufficient to meet the measurement requirements of most high-temperature superconducting tapes in the 4.2K to 77K range on the market; as an alternative, the energized coil can also be replaced with a high-strength neodymium iron boron permanent magnet or a magnet array.

[0028] After passing through the background magnetic field generated by the excitation magnet 1, the high-temperature superconducting tape 4 maintains a bidirectional toroidal magnetization current due to its non-ideal type-II superconductor material properties. Furthermore, because the sample is in a superconducting state with no transmission resistance, the toroidal magnetization current can be maintained for a long time without decay, and its density is equal to the critical current density of the high-temperature superconducting tape 4. .

[0029] Measuring probe 2, such as Figure 2 As shown, it consists of a magnetic circuit core, a fluxgate sensor 5, and a copper strip compensation circuit 6.

[0030] The fluxgate sensor 5 is composed of a high-permeability, low-saturation soft magnetic material core (such as permalloy) wound with an excitation coil 7 and a acquisition coil 8.

[0031] The copper strip compensation circuit 6 has the same width as the high-temperature superconducting strip 4 and is symmetrically arranged on the magnetic circuit core. It consists of two copper flat strips of equal width that are insulated from each other and are short-circuited at the ends.

[0032] The fluxgate sensor 5 and the copper strip compensation circuit 6 are connected to the control and measurement circuit 3 through the fluxgate power supply acquisition line 9 and the copper strip compensation circuit power supply line 10, respectively.

[0033] The fluxgate sensor 5 is used to detect the net residual magnetic flux in the magnetic circuit core; as an alternative, the fluxgate sensor 5 can also be replaced by a Hall sensor or a magnetoresistive sensor to measure the net residual magnetic flux.

[0034] The control and measurement circuit 3 is used to implement PID control through closed-loop negative feedback logic when the net residual magnetic flux is not 0, generate a magnetic flux in the copper strip compensation circuit 6 that is the same size and opposite to that of the high-temperature superconducting strip 4, and calculate the critical current of the high-temperature superconducting strip 4 based on the current in the copper strip compensation circuit 6 when the net residual magnetic flux is 0.

[0035] Control and measurement circuits, such as Figure 3 As shown, it includes: a fluxgate drive circuit, a fluxgate demodulation circuit, a PID control module, and a voltage-controlled current source; The fluxgate drive circuit is used to provide a high-frequency alternating current to the excitation coil 7, so that the high permeability, low saturation soft magnetic material core is periodically saturated in positive and negative directions. The winding alternating current is usually tens of kHz. The acquisition coil 8 is used to read the magnetic flux signal in the high permeability, low saturation soft magnetic material core (when an external magnetic field B is present, the saturation process is modulated, thereby producing a measurable change in the induced signal, which is proportional to the strength of the external constant magnetic field). There are several methods to measure the induced signal and thus determine the external magnetic field B: Option 1: The excitation coil 7 is energized with high-frequency alternating current to saturate the high-permeability, low-saturation soft magnetic core. When there is no external magnetic field, the induced voltage is symmetrical and contains only odd harmonics. When there is an external magnetic field, the high-permeability, low-saturation soft magnetic core saturates asymmetrically, generating even harmonics (such as the second harmonic), the amplitude of which is proportional to the external magnetic field. Option 2: The external magnetic field causes the saturation point of the high-permeability, low-saturation soft magnetic material core to differ between the positive and negative half-cycles, resulting in a difference in the peak value of the induced electromotive force. The strength of the external magnetic field is inferred by measuring the difference in peak values ​​between the positive and negative half-cycles using a detection circuit.

[0036] As an alternative, the fluxgate sensor 5 can be modified in various forms to improve measurement accuracy. The present invention illustrates a simplified parallel field fluxgate sensor, where the winding directions of the excitation coil 7 and the acquisition coil 8 are changed to be perpendicular to each other, resulting in an orthogonal parallel field fluxgate sensor.

[0037] The fluxgate demodulation circuit is used to demodulate the magnetic flux signal to obtain the net residual magnetic flux in the magnetic core. A voltage-controlled current source is used to supply power to the copper strip compensation circuit 6. The PID control module is used to implement PID control through closed-loop negative feedback logic when the net residual magnetic flux is not zero, and adjust the current output of the voltage-controlled current source, thereby generating a magnetic flux in the copper strip compensation circuit 6 that is the same size and opposite to that of the high-temperature superconducting strip 4, so that the magnetic flux generated by the high-temperature superconducting strip 4 and the magnetic flux generated by the copper strip compensation circuit 6 cancel each other out.

[0038] As an alternative, PID control can be further improved into fuzzy PID control, predictive control, etc.

[0039] The calculation method for the current in copper strip compensation circuit 6 is as follows: A resistor with a known resistance is connected in series in the power supply line of copper strip compensation circuit 6. The current in copper strip compensation circuit 6 is obtained by measuring the voltage across the resistor and applying Ohm's law.

[0040] Based on the current in the copper strip compensation circuit 6 when the net remanent magnetic flux is 0, the critical current of the high-temperature superconducting strip 4 is calculated as follows: Through continuous closed-loop negative feedback, the net residual magnetic flux within the modulated magnetic core eventually reaches zero, and the net residual magnetic flux measured by fluxgate sensor 5 is also zero, thus completing the closed-loop control. When the net residual magnetic flux is zero, the current in the copper strip compensation circuit 6... Equivalent to the annular current in high-temperature superconducting tape 4 Half of the magnetic flux, and based on the closed-loop zero flux symmetry of the measuring probe 2, it can be known that the current distribution of the copper strip compensation circuit 6 is exactly the same as the magnetization current distribution in the high-temperature superconducting tape 4. Therefore, the critical current of the high-temperature superconducting tape 4 is as follows:

[0041] in, The critical current of the high-temperature superconducting tape 4; This refers to the current in copper strip compensation circuit 6.

[0042] A constant-temperature container, typically a vacuum Dewar, is used to maintain a vacuum low-temperature environment in the testing zone, keeping the high-temperature superconducting tape 4 in a superconducting state and maintaining it at a preset temperature. The temperature range is typically 4.2K to 77K. In this invention, except for the control and measurement circuit 3, all components are placed in a vacuum Dewar to maintain the high-temperature superconducting tape 4 at a preset temperature. .

[0043] The transmission mechanism is used to drive the high-temperature superconducting tape 4 through the excitation magnet 1 and the measuring probe 2 in sequence, and to record the sample position at the measuring probe 2 in real time, so as to measure the critical current of the high-temperature superconducting tape 4 at each position.

[0044] The transmission mechanism includes: a wire feeding reel 11, a wire taking-up reel 12, a first guide pulley 13, and a second guide pulley 14; Typically, the pay-off reel 11, take-up reel 12, first guide pulley 13, and second guide pulley 14 can be connected to a cryogenic refrigerator cold chain to reduce the temperature of the high-temperature superconducting tape 4 to a preset temperature through conduction cooling. .

[0045] At the start of the measurement, the high-temperature superconducting tape 4 is coiled on the pay-off reel 11. The pay-off reel 11 rotates together with the take-up reel 12. Guided by the first guide pulley 13 and the second guide pulley 14, a preset tension (20N in this invention) is maintained, so that the high-temperature superconducting tape 4 passes through the excitation magnet 1 and the measuring probe 2 in sequence, and is finally collected by the take-up reel 12, thus completing the measurement of the critical current at each position of the high-temperature superconducting tape 4.

[0046] Example 2: Embodiment 2 of the present invention discloses a non-contact continuous non-destructive testing method for the critical current uniformity of high-temperature superconducting tapes using a non-contact continuous non-destructive testing device, comprising: Step 1: After the high-temperature superconducting tape 4 is lowered to the preset temperature in the constant temperature container, the transmission mechanism drives the high-temperature superconducting tape 4 to pass through the excitation magnet 1 and the measuring probe 2 in sequence, and records the sample position at the measuring probe 2 in real time; wherein, after the high-temperature superconducting tape 4 passes through the background magnetic field generated by the excitation magnet 1, it maintains a bidirectional annular magnetization current; when the high-temperature superconducting tape 4 passes through the magnetic circuit core, the net residual magnetic flux in the magnetic circuit core is detected by the fluxgate sensor 5; Step 2: When the fluxgate sensor 5 detects that the net residual flux in the magnetic circuit core is not zero, the control and measurement circuit 3 implements PID control through closed-loop negative feedback logic to generate a magnetic flux in the copper strip compensation circuit 6 that is the same size as and opposite to that of the high-temperature superconducting strip 4. Step 3: Based on the sample position at the measuring probe 2, and according to the current in the copper tape compensation circuit 6 when the net residual magnetic flux is 0, calculate the critical current of the high-temperature superconducting tape 4 at each position.

[0047] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0048] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A non-contact, continuous, non-destructive testing device for the critical current uniformity of high-temperature superconducting tapes, characterized in that, include: Excitation magnet (1), measuring probe (2), control and measuring circuit (3), constant temperature container and transmission mechanism; The excitation magnet (1) is used to generate a background magnetic field and to excite the high-temperature superconducting tape (4) to generate a magnetizing current. The measuring probe (2) is composed of a magnetic circuit core, a fluxgate sensor (5), and a copper strip compensation circuit (6); The fluxgate sensor (5) and the copper strip compensation circuit (6) are respectively connected to the control and measurement circuit (3) through the fluxgate power supply acquisition line (9) and the copper strip compensation circuit power supply line (10); The fluxgate sensor (5) is used to detect the net residual magnetic flux in the magnetic circuit core; The control and measurement circuit (3) is used to implement PID control through closed-loop negative feedback logic when the net residual magnetic flux is not 0, generate a magnetic flux in the copper strip compensation circuit (6) that is the same size and opposite to that of the high temperature superconducting strip (4), and calculate the critical current of the high temperature superconducting strip (4) based on the current in the copper strip compensation circuit (6) when the net residual magnetic flux is 0. The constant temperature container is used to maintain the vacuum low temperature environment test area, so that the high temperature superconducting tape (4) is in a superconducting state and to maintain the high temperature superconducting tape (4) at a preset temperature. The transmission mechanism is used to drive the high-temperature superconducting tape (4) through the excitation magnet (1) and the measuring probe (2) in sequence, and to record the sample position at the measuring probe (2) in real time, so as to measure the critical current of the high-temperature superconducting tape (4) at each position.

2. The non-contact, continuous, non-destructive testing device for the critical current uniformity of high-temperature superconducting tapes according to claim 1, characterized in that, The excitation magnet (1) is a pair of discrete energized coils, and the intensity of the background magnetic field is more than twice the penetration field intensity of the high-temperature superconducting tape (4).

3. The non-contact, continuous, non-destructive testing device for the critical current uniformity of high-temperature superconducting tapes according to claim 1, characterized in that, After passing through the background magnetic field generated by the excitation magnet (1), the high-temperature superconducting tape (4) maintains a bidirectional annular magnetization current, and the annular magnetization current is maintained without decay, with a density equal to the critical current density of the high-temperature superconducting tape (4).

4. The non-contact, continuous, non-destructive testing device for the critical current uniformity of high-temperature superconducting tapes according to claim 1, characterized in that, The fluxgate sensor (5) is composed of a high-permeability, low-saturation soft magnetic material core wound with an excitation coil (7) and a acquisition coil (8).

5. The non-contact, continuous, non-destructive testing device for the critical current uniformity of high-temperature superconducting tapes according to claim 1, characterized in that, The copper strip compensation circuit (6) has the same width as the high-temperature superconducting strip (4) and is symmetrically arranged on the magnetic circuit core with the high-temperature superconducting strip (4). It is composed of two copper flat strips of equal width that are insulated from each other and are short-circuited at the ends.

6. The non-contact, continuous, non-destructive testing device for the critical current uniformity of high-temperature superconducting tapes according to claim 4, characterized in that, The control and measurement circuit (3) includes: a fluxgate drive circuit, a fluxgate demodulation circuit, a PID control module, and a voltage-controlled current source; The fluxgate drive circuit is used to provide high-frequency alternating current to the excitation coil (7), so that the high permeability low saturation soft magnetic material core is periodically saturated in positive and negative directions, and the acquisition coil (8) is used to read the magnetic flux signal in the high permeability low saturation soft magnetic material core. The fluxgate demodulation circuit is used to demodulate the flux signal to obtain the net residual flux in the magnetic core. The voltage-controlled current source is used to supply power to the copper strip compensation circuit (6); The PID control module is used to implement PID control through closed-loop negative feedback logic when the net residual magnetic flux is not zero, and adjust the current output of the voltage-controlled current source, thereby generating a magnetic flux in the copper strip compensation circuit (6) that is the same size and opposite to that of the high-temperature superconducting strip.

7. The non-contact, continuous, non-destructive testing device for the critical current uniformity of high-temperature superconducting tapes according to claim 1, characterized in that, The calculation method for the current in the copper strip compensation circuit (6) is as follows: A resistor with a known resistance is connected in series in the power supply line of the copper strip compensation circuit (6). The current in the copper strip compensation circuit (6) is obtained by measuring the voltage across the resistor according to Ohm's law.

8. The non-contact, continuous, non-destructive testing device for the critical current uniformity of high-temperature superconducting tapes according to claim 1, characterized in that, Based on the current in the copper strip compensation circuit (6) when the net residual magnetic flux is 0, the critical current of the high-temperature superconducting strip (4) is calculated as follows: When the net residual magnetic flux is 0, the current in the copper strip compensation circuit (6) is equivalent to half of the annular current in the high-temperature superconducting tape (4). Based on the closed-loop zero magnetic flux symmetry of the measuring probe (2), the critical current of the high-temperature superconducting tape (4) is as follows: in, The critical current of the high-temperature superconducting tape (4) is given by . The current in the copper strip compensation circuit (6) is denoted as .

9. The non-contact, continuous, non-destructive testing device for the critical current uniformity of high-temperature superconducting tapes according to claim 1, characterized in that, The transmission mechanism includes: a pay-off reel (11), a take-up reel (12), a first guide pulley (13), and a second guide pulley (14). At the start of the measurement, the high-temperature superconducting tape (4) is coiled on the pay-off reel (11). The pay-off reel (11) rotates together with the take-up reel (12). Guided by the first guide pulley (13) and the second guide pulley (14), the preset tension is maintained, so that the high-temperature superconducting tape (4) passes through the excitation magnet (1) and the measuring probe (2) in sequence, and is finally collected by the take-up reel (12), thus completing the measurement of the critical current at each position of the high-temperature superconducting tape (4).

10. A method for continuous non-destructive testing of the critical current uniformity of high-temperature superconducting tape using a non-contact continuous non-destructive testing device for critical current uniformity of high-temperature superconducting tape as described in any one of claims 1-9, characterized in that, include: Step 1: After the high-temperature superconducting tape (4) is lowered to a preset temperature in the constant temperature container, the transmission mechanism drives the high-temperature superconducting tape (4) to pass through the excitation magnet (1) and the measuring probe (2) in sequence, and records the sample position at the measuring probe (2) in real time; wherein, after the high-temperature superconducting tape (4) passes through the background magnetic field generated by the excitation magnet (1), it maintains a bidirectional annular magnetization current; when the high-temperature superconducting tape (4) passes through the magnetic circuit core, the net residual magnetic flux in the magnetic circuit core is detected by the fluxgate sensor (5); Step 2: When the fluxgate sensor (5) detects that the net residual flux in the magnetic circuit core is not zero, the control and measurement circuit (3) implements PID control through closed-loop negative feedback logic to generate a magnetic flux in the copper strip compensation circuit (6) that is the same size as and opposite to that of the high-temperature superconducting strip (4). Step 3: Based on the sample position of the high-temperature superconducting tape (4) passing through the measuring probe (2), and according to the current in the copper tape compensation circuit (6) when the net residual magnetic flux is 0, calculate the critical current of the high-temperature superconducting tape (4) at each position.

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