Non-contact continuous nondestructive testing device and method for critical current uniformity of high-temperature superconducting tape

Abstract

The invention discloses a non-contact continuous nondestructive testing device and method for critical current uniformity of a high-temperature superconducting tape, which is applied to the field of superconducting material detection, and comprises an excitation magnet for generating a background magnetic field and exciting the high-temperature superconducting tape to generate magnetization current; the measuring probe consists of a magnetic circuit iron core, a fluxgate sensor and a copper strip compensation loop; the fluxgate sensor and the copper strip compensation loop are respectively connected with the control and measurement circuit through a fluxgate power supply acquisition circuit and a copper strip compensation loop power supply circuit; and the control and measurement circuit is used for implementing PID (Proportion Integration Differentiation) control through closed-loop negative feedback when the fluxgate sensor detects that the net residual magnetic flux in the magnetic circuit iron core is not zero, generating magnetic flux which is equal to and opposite to the high-temperature superconducting strip in size in the copper strip compensation loop, and calculating critical current according to current in the copper strip compensation loop when the net residual magnetic flux is zero. According to the method, rapid and accurate measurement of the critical current uniformity of the high-temperature superconducting strip without depending on a Hall sensor and calibration back calculation is realized.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of superconducting material detection, in particular to a non-contact type high-temperature superconducting tape critical current uniformity continuous nondestructive detection device and method. BACKGROUND

[0002] Superconducting materials have an irreplaceable core position in fusion reactors, particle accelerators, strong field magnets, superconducting motors and other high-end equipment due to their zero resistance characteristics and strong magnetic field carrying capacity. High-temperature superconducting tapes represented by copper oxide superconductors have become the most important superconducting material in engineering applications. Superconducting tapes often work in extreme low temperature (4.2-77K), strong magnetic field (>20T) and complex cyclic load environment. As a key component of superconducting equipment, the critical current (Ic) uniformity of the superconducting tape directly determines the electromagnetic performance and safety threshold of the equipment. The crystal structure of high-temperature superconducting tapes determines that local defects are easily generated in the production of the material and the assembly of the equipment, which causes the local critical current to decrease, which greatly threatens the reliability and stability of the superconducting equipment. Therefore, it is necessary to continuously measure the critical current uniformity of the high-temperature superconducting long tape used for the manufacture of superconducting equipment to ensure that the critical current of the superconducting tape meets the requirements of the equipment manufacture in the whole and in the local.

[0003] The existing measurement methods of the critical current of high-temperature superconducting tapes can be divided into contact type and non-contact type. Among them, the contact type measurement method is represented by the "four lead method". The method injects a step-type direct current into the superconducting tape and monitors the voltage change. When the voltage drop per unit length of the tape reaches 1 muV / cm, the corresponding current value is the critical current. The method needs to be in direct contact with the tape, which easily introduces contact resistance, causes local overheating and even damages the tape, and has low measurement efficiency, and it is difficult to realize continuous and rapid measurement of long tapes (hundreds of meters).

[0004] However, the existing non-contact measurement method generally has the problem of low precision. For example, the Hall probe method, which is widely used, calculates the magnetization critical current of the superconducting tape by measuring the residual magnetic field distribution after magnetization. This method is extremely sensitive to the relative position of the tape and the probe. A hundred-micron shift can cause an error of more than 15% in the measurement result. The measurer cannot distinguish whether the change in the reading is due to the position shift or the change in the performance of the tape. For example, the magnetic circuit method improves the reading method of the residual magnetic field strength on the basis of the Hall probe method. The reading method of the residual magnetic field strength is changed to reading the residual magnetic moment, which improves the dependence of the measurement result on the positioning of the probe. However, because it still relies on the Hall sensor to measure the magnetic field, the background measurement noise of the sensor itself is usually in the range of 3-5 amperes. In addition, the residual magnetization current in the tape is difficult to calculate quantitatively, and needs to be calibrated separately for each sample, which increases the complexity of obtaining the measurement result. Moreover, the Hall sensor element, especially the low-temperature Hall sensor element that can work below the critical temperature of superconducting, has the problems of limited precision, low working stability, dependence on specific suppliers, and high price.

[0005] Therefore, how to provide a non-contact high-temperature superconducting tape critical current uniformity continuous non-destructive detection device and method that can not rely on a Hall sensor and can realize fast and accurate measurement of the critical current uniformity of a high-temperature superconducting tape is a problem that those skilled in the art need to solve. SUMMARY

[0006] Therefore, the present application provides a non-contact high-temperature superconducting tape critical current uniformity continuous non-destructive detection device and method, which can realize non-contact continuous and fast detection of the critical current uniformity of a high-temperature superconducting tape without additional calibration. Moreover, the present application does not need to use a Hall sensor, which reduces the manufacturing cost of the measurement probe part.

[0007] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions: A non-contact high-temperature superconducting tape critical current uniformity continuous non-destructive detection device, comprising: an excitation magnet, a measurement probe, a control and measurement circuit, a constant-temperature container, and a transmission mechanism. The excitation magnet is used to generate a background magnetic field to excite the high-temperature superconducting tape to generate a magnetization current. The measurement probe is composed of a magnetic circuit core, a fluxgate sensor, and a copper tape compensation loop. The fluxgate sensor and the copper tape compensation loop are connected with the control and measurement circuit through a fluxgate power supply acquisition circuit and a copper tape compensation loop power supply circuit, respectively. The fluxgate sensor is used to detect the net residual magnetic flux in the magnetic circuit core. A control and measurement circuit is configured to implement PID control through closed-loop negative feedback logic when the net residual magnetic flux is not 0, to generate a magnetic flux in the copper tape compensation loop that is equal in magnitude and opposite in direction to the high-temperature superconducting tape, and to calculate the critical current of the high-temperature superconducting tape according to the current in the copper tape compensation loop when the net residual magnetic flux is 0; A constant-temperature container is configured to maintain a vacuum low-temperature environment test area, to maintain the high-temperature superconducting tape in a superconducting state, and to maintain the high-temperature superconducting tape at a preset temperature; A transmission mechanism is configured to drive the high-temperature superconducting tape to pass through the excitation magnet and the measurement probe in sequence, and to record the position of the sample passing through the measurement 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 separate energized coils, and the strength of the background magnetic field is higher than twice the penetration field strength of the high-temperature superconducting tape.

[0009] Optionally, the high-temperature superconducting tape maintains a positive and negative bidirectional annular magnetization current after passing through the background magnetic field generated by the excitation magnet, and the annular magnetization current is maintained without attenuation, and the density is 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 an acquisition coil.

[0011] Optionally, the copper tape compensation loop has the same width as the high-temperature superconducting tape, and is symmetrically arranged on the magnetic circuit core with the high-temperature superconducting tape, and is composed of two flat copper tapes with the same width and mutual insulation, and is connected in short circuit at the end.

[0012] Optionally, the control and measurement circuit includes a fluxgate drive circuit, a fluxgate demodulation circuit, a PID control module, and a voltage-controlled current source. The fluxgate drive circuit is configured to provide a high-frequency alternating current for 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 communication signal in the high-permeability low-saturation soft magnetic material core. The fluxgate demodulation circuit is configured to demodulate the magnetic communication signal to obtain the net residual magnetic flux in the magnetic circuit core. The voltage-controlled current source is configured to supply a current to the copper tape compensation loop. The PID control module is configured to implement PID control through closed-loop negative feedback logic when the net residual magnetic flux is not 0, to adjust the current output of the voltage-controlled current source, so as to generate a magnetic flux in the copper tape compensation loop that is equal in magnitude and opposite in direction to the high-temperature superconducting tape.

[0013] Optionally, the calculation method of the current in the copper tape compensation loop 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 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 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 device for continuous non-destructive testing of critical current uniformity of high temperature superconducting tapes, characterized in that, The application relates to a high-temperature superconducting tape critical current test device. The device comprises an excitation magnet (1), a measuring probe (2), a control and measurement circuit (3), a constant-temperature container and a transmission mechanism. The excitation magnet (1) is used for generating a background magnetic field to excite a high-temperature superconducting tape (4) to generate magnetization current. The measuring probe (2) is composed of a magnetic circuit core, a fluxgate sensor (5) and a copper belt compensation loop (6). The fluxgate sensor (5) and the copper belt compensation loop (6) are connected with the control and measurement circuit (3) through a fluxgate power supply acquisition circuit (9) and a copper belt compensation loop power supply circuit (10) respectively. The fluxgate sensor (5) is used for detecting the net residual magnetic flux in the magnetic circuit core. The control and measurement circuit (3) is used for implementing PID control through closed-loop negative feedback logic when the net residual magnetic flux is not 0, generating magnetic flux in the copper belt compensation loop (6) which is equal to and opposite to the high-temperature superconducting tape (4), and calculating the critical current of the high-temperature superconducting tape (4) according to the current in the copper belt compensation loop (6) when the net residual magnetic flux is 0. The constant-temperature container is used for maintaining a vacuum low-temperature environment test area, making the high-temperature superconducting tape (4) in a superconducting state and maintaining the high-temperature superconducting tape (4) at a preset temperature. The transmission mechanism is used for driving the high-temperature superconducting tape (4) to pass through the excitation magnet (1) and the measuring probe (2) in sequence and recording the sample position passing through 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 device for non-contact continuous non-destructive testing of critical current homogeneity of high-temperature superconducting tapes according to claim 1, characterized in that, The excitation magnet (1) is a pair of separated power coils, and the intensity of the background magnetic field is higher than twice the penetration field intensity of the high-temperature superconducting tape (4).

3. The device for non-contact continuous and non-destructive measurement of critical current homogeneity of high-temperature superconducting tapes according to claim 1, characterized in that, The high-temperature superconducting tape (4) maintains positive and negative bidirectional annular magnetization current after passing through the background magnetic field generated by the excitation magnet (1), and the annular magnetization current is maintained without attenuation, and the density is the critical current density of the high-temperature superconducting tape (4).

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

5. The non-contact device for continuous and non-destructive measurement of critical current uniformity of a high temperature superconducting tape of claim 1, wherein The copper belt compensation loop (6) is the same in width as the high-temperature superconducting tape (4) and is symmetrically arranged on the magnetic circuit core, and is composed of two equal-width copper flat belts which are insulated from each other and are connected in short circuit at the ends.

6. The non-contact device for continuous and non-destructive measurement of critical current uniformity of a high temperature superconducting tape of claim 4, wherein The control and measurement circuit (3) comprises a fluxgate driving circuit, a fluxgate demodulation circuit, a PID control module and a voltage-controlled current source. The fluxgate driving circuit is used for providing high-frequency alternating current for the excitation coil (7), so that the high-magnetic-permeability low-saturation soft magnetic material core is periodically positively and negatively reversed saturation, and the acquisition coil (8) is used for reading the magnetic communication signal in the high-magnetic-permeability low-saturation soft magnetic material core. The fluxgate demodulation circuit is used for demodulating the magnetic communication signal to obtain the net residual magnetic flux in the magnetic circuit core. The voltage-controlled current source is used for supplying power current for the copper belt compensation loop (6). The PID control module is configured to implement PID control through closed-loop negative feedback logic to adjust the current output of the voltage-controlled current source when the net residual magnetic flux is not 0, so as to generate a magnetic flux in the copper tape compensation loop (6) which is equal in size and opposite in direction to the high-temperature superconducting tape.

7. The non-contact device for continuous and non-destructive measurement of critical current uniformity of a high temperature superconducting tape of claim 1, wherein The method for calculating the current in the copper tape compensation loop (6) is specifically as follows: In the power supply circuit of the copper tape compensation loop (6), a resistor with a known resistance is connected in series, and the current in the copper tape compensation loop (6) is obtained according to Ohm's law by measuring the voltage across the resistor.

8. The non-contact device for continuous and non-destructive measurement of critical current uniformity of a high temperature superconducting tape of claim 1, wherein, According to the current in the copper tape compensation loop (6) when the net residual magnetic flux is 0, the critical current of the high-temperature superconducting tape (4) is calculated, which is specifically as follows: When the net residual magnetic flux is 0, the current in the copper tape compensation loop (6) is equivalent to half of the annular current in the high-temperature superconducting tape (4), and according to the closed-loop zero-flux symmetry of the measurement probe (2), the critical current of the high-temperature superconducting tape (4) is as follows: wherein is the critical current of the high temperature superconducting tape (4); is the current in the copper tape compensation loop (6).

9. The non-contact device for continuous and non-destructive measurement of critical current uniformity of a high temperature superconducting tape of claim 1, wherein, 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 measurement, the high-temperature superconducting tape (4) is wound on the pay-off reel (11), the pay-off reel (11) is rotated together with the take-up reel (12), and the first guide pulley (13) and the second guide pulley (14) are used for guidance to maintain a predetermined tension, so that the high-temperature superconducting tape (4) passes through the excitation magnet (1) and the measurement probe (2) in turn, and is finally collected by the take-up reel (12), thereby completing the measurement of the critical current of the high-temperature superconducting tape (4) at each position.

10. A method for non-destructive testing of the critical current uniformity of a high temperature superconducting tape using the device of any one of claims 1 to 9, characterized in that It includes: Step 1: After the high-temperature superconducting tape (4) is lowered to a predetermined 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 measurement probe (2) in turn, and records the position of the sample passing through the measurement 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), the annular magnetization current is maintained in positive and negative directions; 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 magnetic flux in the magnetic circuit core is not 0, the control and measurement circuit (3) implements PID control through closed-loop negative feedback logic to generate a magnetic flux in the copper tape compensation loop (6) which is equal in size and opposite in direction to the high-temperature superconducting tape (4); Step 3: Based on the position of the sample passing through the measurement probe (2) of the high-temperature superconducting tape (4), and according to the current in the copper tape compensation loop (6) when the net residual magnetic flux is 0, the critical current of the high-temperature superconducting tape (4) at each position is calculated.

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