A superconducting tape magnetic field measurement device and method based on Hall sensor

Abstract

The present invention discloses a superconducting tape magnetic field measurement device and method based on a Hall sensor, comprising: an electronic universal tensile testing machine, a high-precision Hall sensor, a liquid nitrogen tank, a current loading system and an excitation magnet; wherein the clamp of the electronic universal tensile testing machine is placed in the liquid nitrogen tank, the superconducting tape is fixed between the upper and lower clamps of the electronic universal tensile testing machine, the current loading system applies current to the superconducting tape when power is turned on, the excitation magnet performs excitation processing on the superconducting tape to provide a magnetic field when excitation is performed, and the high-precision Hall sensor is controlled by a three-dimensional path control system to perform point-by-point scanning and measurement of the magnetic field on the surface of the superconducting tape. The technical solution of the present invention is adopted to realize the high-precision measurement and evaluation of the electromagnetic performance of the second-generation high-temperature superconducting tape under in-situ stretching, which is suitable for two different excitation modes of current carrying and magnetization; it has the characteristics of high precision, high stability, high spatial resolution, etc., and is easy to operate and has a wide range of applications.

Description

Technical Field

[0001] The invention belongs to the technical field of superconducting materials, and in particular relates to a device and method for measuring the magnetic field of a superconducting strip based on a Hall sensor. Background Art

[0002] The second generation of high temperature superconducting tape is a superconducting material with important application prospects. Because it has a higher critical temperature and maintains a higher current density under high magnetic fields, it plays an important role in many fields such as transportation, energy, electricity and medical treatment. During the preparation and application process, it is necessary to accurately measure and evaluate the magnetic field performance of the second generation of high temperature superconducting tape to achieve its normal operation and performance optimization.

[0003] Existing magnetic field measurement methods mainly include magnetometer, magnetic force microscope, nuclear magnetic resonance, etc. These methods can meet the needs of magnetic field measurement to a certain extent, but they have some defects and shortcomings.

[0004] The magnetometer is a measurement method based on changes in magnetic flux, but since the second-generation high-temperature superconducting tapes have a large range of magnetic flux changes, high-precision instruments are required for measurement. At the same time, corrections for environmental factors such as temperature and humidity are also required, resulting in high measurement costs. The magnetic force microscope is a measurement method based on magnetic field distribution imaging, but it requires the sample to be placed in a vacuum environment, and the sample needs to be prepared and polished, so it is difficult to adapt to complex environments and material changes. Nuclear magnetic resonance is a measurement method based on changes in the magnetic moment of nuclear spins, but it requires the use of expensive equipment and high-power magnetic field generators, so the measurement cost is high.

[0005] Defects and shortcomings of the existing technology:

[0006] Low measurement accuracy: Existing magnetic field measurement methods are difficult to accurately measure the magnetic field strength and distribution of second-generation high-temperature superconducting tapes, especially in high magnetic field environments, where the measurement error is large. This is mainly due to the limitations of measurement principles and equipment.

[0007] Slow measurement speed: Existing magnetic field measurement methods require complex operations and processing, resulting in slow measurement speeds that are difficult to meet the needs of real-time monitoring and rapid evaluation. This is mainly due to the need for sample preparation, data transmission and processing during the measurement process.

[0008] Expensive equipment: Existing magnetic field measurement methods require the use of high-precision instruments and equipment, resulting in high measurement costs and being unfavorable for promotion and application. This is mainly due to the high cost of equipment purchase and maintenance.

[0009] Difficult to adapt to complex environmental changes: The magnetic field measurement of the second-generation high-temperature superconducting tape needs to be carried out in the actual application environment, but the existing magnetic field measurement methods are difficult to adapt to complex environmental changes, which is mainly due to the limitations of measurement equipment and methods. Most of the existing devices can only realize one of the following methods: powering or excitation of superconducting tapes. The loading method is single and it is difficult to meet the needs under different working conditions.

[0010] In summary, although some magnetic field measurement methods have been developed, there are still some problems in practical applications. The existing magnetic field measurement devices are difficult to meet the magnetic field measurement requirements of the second-generation high-temperature superconducting tapes. Summary of the invention

[0011] The technical problem to be solved by the present invention is to provide a superconducting tape magnetic field measurement device and method based on Hall sensors, so as to accurately measure and evaluate the magnetic field performance of second-generation high-temperature superconducting tapes, so as to improve measurement accuracy and efficiency, reduce measurement costs, and adapt to complex environmental changes; it has the characteristics of high precision, high stability, high spatial resolution, etc., and is easy to operate and has a wide range of applications.

[0012] To achieve the above object, the present invention adopts the following technical solution:

[0013] A superconducting tape magnetic field measuring device based on a Hall sensor comprises: an electronic universal tensile testing machine, a high-precision Hall sensor, a liquid nitrogen tank, a current loading system and an excitation magnet; wherein the clamp of the electronic universal tensile testing machine is placed in the liquid nitrogen tank, the superconducting tape is fixed between the upper and lower clamps of the electronic universal tensile testing machine, the current loading system applies current to the superconducting tape when power is turned on, the excitation magnet performs excitation processing on the superconducting tape to provide a magnetic field when excitation is performed, and the high-precision Hall sensor is controlled by a three-dimensional path control system to perform point-by-point scanning and measurement of the magnetic field on the surface of the superconducting tape.

[0014] Preferably, the electronic universal tensile testing machine is used to perform in-situ tensile deformation on the superconducting tape. During the measurement process, the electromagnetic behavior of the superconducting tape under different stress states is measured by adjusting the tensile rate and deformation amount of the electronic universal tensile testing machine.

[0015] Preferably, the method further comprises: a signal acquisition system for collecting magnetic field data on the surface of the superconducting tape, and for monitoring and recording the changes in the magnetic field on the surface of the superconducting tape in real time.

[0016] Preferably, the Hall sensor is composed of an external protective groove and an internal buried Hall chip; the Hall chip is made of gallium arsenide, with geometric dimensions of 0.3mm×0.3mm×0.2mm, an active area diameter of 0.05mm, a frequency range of DC-1kHz, a full scale of 3T, an accuracy of ±0.2%, an operating temperature range of -269℃~+75℃, a temperature coefficient of 0.03% / ℃, an operating current of 2-5mA, and a sensitivity of 10mT / mV.

[0017] Preferably, the scanning path of the Hall sensor is: starting from the middle position of the scanning length a to scan to the right half area, and then returning to the initial position in the middle of the strip to continue scanning to the left. After completing the scanning process of a straight line, it moves upward from the left boundary area by a unit resolution along the b direction, and returns to the middle part of the second straight line to be scanned, completing a movement cycle, and repeating the next cycle until the entire a×b area of ​​the strip is scanned.

[0018] Preferably, the three-dimensional path control system uses OM motor two-phase single-axis stepper motors respectively built in the x-axis, y-axis and z-axis directions to realize the movement of the Hall sensor bracket in three-dimensional space and measure the magnetic field in any area on the surface of the superconducting tape.

[0019] The present invention provides a method for measuring a magnetic field of a superconducting strip based on a Hall sensor, comprising the following steps:

[0020] Step 1, placing the clamp of the electronic universal tensile testing machine in a liquid nitrogen tank, and fixing the superconducting tape between the upper and lower clamps of the electronic universal tensile testing machine;

[0021] Step 2, controlling the movement of the Hall sensor in the three-dimensional space by a three-dimensional path control system to measure the magnetic field on the surface of the superconducting tape; wherein, the current loading system supplies power when power is turned on, and the excitation magnet provides the magnetic field when excitation is performed;

[0022] Step 3: Collect magnetic field data on the surface of the superconducting tape through a signal acquisition system, and monitor and record the magnetic field changes on the surface of the superconducting tape in real time;

[0023] Step 4: adjust the load acting on the superconducting tape by an electronic universal tensile testing machine to perform in-situ tensile deformation on the superconducting tape, repeat steps 2 and 3, and measure the electromagnetic behavior of the superconducting tape under different stress states.

[0024] Preferably, the Hall sensor is composed of an external protective groove and an internal buried Hall chip; the Hall chip is made of gallium arsenide, with geometric dimensions of 0.3mm×0.3mm×0.2mm, an active area diameter of 0.05mm, a frequency range of DC-1kHz, a full scale of 3T, an accuracy of ±0.2%, an operating temperature range of -269℃~+75℃, a temperature coefficient of 0.03% / ℃, an operating current of 2-5mA, and a sensitivity of 10mT / mV.

[0025] Preferably, the scanning path of the Hall sensor is: starting from the middle position of the scanning length a to scan to the right half area, and then returning to the initial position in the middle of the strip to continue scanning to the left. After completing the scanning process of a straight line, it moves upward from the left boundary area by a unit resolution along the b direction, and returns to the middle part of the second straight line to be scanned, completing a movement cycle, and repeating the next cycle until the entire a×b area of ​​the strip is scanned.

[0026] The present invention realizes the surface magnetic field measurement of the second-generation high-temperature superconducting tape based on the Hall sensor, can measure the magnetic field on the surface of the superconducting tape under both power-on and excitation conditions, and can change the tensile load through the electronic universal tensile testing machine to achieve in-situ stretching. Through the present invention, the magnetic field performance of the second-generation high-temperature superconducting tape can be accurately measured and evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0028] Figure 1 It is a schematic structural diagram of a superconducting tape magnetic field measuring device based on a Hall sensor according to an embodiment of the present invention;

[0029] Figure 2 This is the front view of the electronic universal tensile testing machine;

[0030] Figure 3 is a schematic diagram of a scanning path of a Hall sensor;

[0031] Figure 4 The present invention is a measurement flow chart of a superconducting tape magnetic field measurement device based on a Hall sensor;

[0032] Figure 5 Schematic diagram of magnetic field distribution of superconducting tape under 10N tensile load when power is applied;

[0033] Figure 6 The magnetic field distribution of the superconducting tape under different tensile loads when the power is on; (a) is 250N, (b) is 320N, (c) is 325N, and (d) is 330N;

[0034] Figure 7 The magnetic field distribution of the superconducting tape under different tensile loads when the power is on; (a) is 10N, (b) is 250N, (c) is 320N, (d) is 325N, and (e) is 330N;

[0035] Figure 8 Schematic diagram of magnetic field distribution of superconducting tape under 10N tensile load under excitation;

[0036] Fig. 9 The magnetic field distribution of the superconducting tape under different tensile loads under excitation; (a) is 10N, (b) is 250N, (c) is 320N, (d) is 325N, (e) is 330N, and (f) is 335N;

[0037] Fig.10 Figure 2 shows the magnetic field distribution of superconducting tape under different tensile loads under excitation; (a) is 10N, (b) is 250N, (c) is 320N, (d) is 325N, (e) is 330N, and (f) is 335N. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] Embodiment 1:

[0041] like Figure 1As shown, an example of an embodiment of the present invention provides a superconducting tape magnetic field measuring device based on a Hall sensor: including: an electronic universal tensile testing machine, a three-dimensional path control system, a high-precision Hall sensor, a liquid nitrogen tank, a current loading system, an excitation magnet, and a signal acquisition system. Among them, the electronic universal tensile testing machine is responsible for providing a mechanical load, which can provide both static mechanical load holding and variable tensile load to achieve in-situ stretching. The clamp of the electronic universal tensile testing machine is placed in a liquid nitrogen tank, and the superconducting tape is fixed between the upper and lower clamps of the electronic universal tensile testing machine. When power is turned on, the current loading system applies current to the superconducting tape, and when excitation is performed, the excitation magnet excites the superconducting tape to provide a magnetic field. There is a transparent glass window on the front side of the liquid nitrogen tank, through which the movement of the Hall sensor in the experiment can be observed.

[0042] Further, if Figure 2 As shown, the electronic universal tensile testing machine is used to provide tensile loads of different sizes, which can achieve in-situ stretching. During the measurement process, the superconducting tape is fixed on the fixture of the electronic universal tensile testing machine to ensure the stability of the tape during the measurement process. At the same time, the electronic universal tensile testing machine can perform in-situ tensile deformation on the superconducting tape. The electronic universal tensile testing machine uses high-precision sensors and control systems to provide accurate tensile deformation for superconducting tapes. During the measurement process, by adjusting the tensile rate and deformation of the electronic universal tensile testing machine, the behavior of the superconducting tape under different stress states can be simulated, so as to more accurately measure its surface magnetic field. The maximum load of the electronic universal tensile testing machine is 25kN, and the resolution can reach 1 / 300000; the loading speed can be adjusted within the range of 0.0025-500mm / min; the crossbeam displacement range is 570mm, the moving range is large, and it can be flexibly adjusted according to the experimental conditions, which can fully meet the experimental needs. The low-temperature fixture material is brass, which has the advantages of excellent mechanical properties and good wear resistance. It is mainly composed of two clamping blocks and an external frame. The two clamping blocks can be tightened counterclockwise to clamp the strip. The inner side of the clamping block contacts the strip surface in a slightly serrated shape, which increases the friction of the clamp surface. Therefore, in the process of cooling from room temperature to liquid nitrogen temperature, the slippage caused by the cooling and shrinkage of the strip can be avoided to the greatest extent.

[0043] Furthermore, the three-dimensional path control system is used to control the movement of the Hall sensor in three-dimensional space. Through the control of the matlab program, the precise movement of the Hall sensor can be achieved to ensure the accuracy and reliability of the measurement results. During the measurement process, by adjusting the movement rate and movement range of the three-dimensional path control system, more comprehensive and accurate magnetic field information can be obtained. The three-dimensional path control system has the characteristics of high precision and high stability, which can ensure the accuracy and reliability of the measurement results. Based on the vertical fixed placement of the superconducting tape in the existing test platform test, in order to realize the test of the magnetic field distribution characteristics on the surface of the superconducting tape, it is necessary to move the Hall sensor to realize the test of different areas on the surface of the tape. In the present invention, the three-dimensional path control system uses three OM motor two-phase single-axis stepper motors imported from Japan, which are respectively built in the x-axis, y-axis and z-axis directions to realize the movement of the Hall sensor bracket in three-dimensional space, and the magnetic field in any area on the surface of the superconducting tape can be measured.

[0044] Furthermore, high-precision Hall sensors are used to measure the magnetic field on the surface of superconducting tapes. Due to its high-precision characteristics, it can accurately capture tiny magnetic field changes on the surface of superconducting tapes. The Hall sensor uses a high-precision sensor, which can achieve accurate measurement of tiny magnetic field changes on the surface of superconducting tapes, thereby obtaining a true and accurate magnetic field distribution. The Hall sensor is composed of an external protective groove and an internal buried Hall chip. The main component of the Hall chip used in the present invention is gallium arsenide, with geometric dimensions of 0.3mm×0.3mm×0.2mm, an active area diameter of 0.05mm, a frequency range of DC-1kHz, a full scale of 3T, an accuracy of ±0.2%, an operating temperature range of -269℃~+75℃, a temperature coefficient of 0.03% / ℃, an operating current of 2-5mA, and a sensitivity of 10mT / mV. Figure 3As shown in the figure, when the Hall sensor performs a full-field micromagnetic scan on the area a×b, in order to obtain the magnetic field on the surface of the strip more finely, so as to better explore the electromagnetic field distribution characteristics on the surface of the superconducting strip, the scanning path of the Hall sensor is: starting from the middle position of the scanning length a to scan the right half area, returning to the initial position in the middle of the strip after completion and continuing to scan to the left, after completing the scanning process of a straight line, move upward from the left boundary area by a unit resolution along the b direction, and return to the middle part of the second straight line to be scanned, completing a movement cycle, and then repeating the next cycle until the entire area a×b of the strip is scanned. The spatial resolution of the magnetic field that can be detected by this system can reach 50μm×50μm. In addition, a connecting rod is required to connect the three-dimensional path control system and the packaged Hall sensor. The initial part is a stainless steel tube with a diameter of 8mm fixed on the three-dimensional path control system. In order to prevent the Hall sensor from being affected by electromagnetic interference, the middle section is made of a columnar connecting rod made of glass fiber with a diameter of 8 mm and a length of 20 cm. It can maintain good rigidity at low temperatures and ensure that the Hall sensor head has strong stability when scanning in a liquid nitrogen tank.

[0045] Furthermore, the liquid nitrogen tank is used to provide a low temperature environment to ensure that the superconducting tape maintains a superconducting state during the measurement process. By pouring liquid nitrogen into the liquid nitrogen tank, the temperature can be quickly lowered to allow the superconducting tape to reach a superconducting state.

[0046] Furthermore, the current loading system should include a superconducting power supply, a nanovoltmeter, a Hall current sensor, a Labview acquisition instrument, a copper wire, etc. The current loading system is used to apply current to the superconducting tape and monitor it in real time. The current loading system can accurately control the current to ensure the accuracy of the measurement results. During the measurement process, the magnitude and rate of the input current can be changed by adjusting the control parameters of the superconducting power supply. The superconducting power supply can provide direct current to the experimental sample, and the current range provided is 0-600A, which can fully meet the current loading requirements. Labview collects the sample current and voltage signals in real time, and the nanovoltmeter is used to monitor the surface voltage of the superconducting tape. In the case of superconducting tape quenching, power-off protection can be performed through Labview.

[0047] Furthermore, the excitation magnet is used to generate the required magnetic field. By loading the current of the excitation coil, the excitation treatment of the superconducting tape can be achieved. The rated voltage of the magnet is 24V, the rated power is 25W, and it can operate normally in a liquid nitrogen environment. During the measurement process, by adjusting the DC power supply connected to it, the input current and input voltage of the magnet can be changed, and then the magnetic field size can be changed. When excitation treatment is performed on high-temperature superconducting tapes, it is necessary to ensure that the external magnetic field is greater than 2 times the penetration magnetic field of the high-temperature superconducting tape.

[0048] Furthermore, the signal acquisition system is used to collect magnetic field data on the surface of the superconducting tape. Through the signal acquisition system, the magnetic field changes on the surface of the superconducting tape can be monitored and recorded in real time. At the same time, the signal acquisition system can also process and analyze the measurement data in real time. The signal acquisition system uses high-precision data acquisition and processing technology to provide more accurate measurement results and provide basic data for subsequent data processing and analysis.

[0049] During the measurement process, the superconducting tape is first fixed on the fixture of the electronic universal tensile testing machine, and the fixture is placed in a liquid nitrogen tank. Liquid nitrogen is poured into the liquid nitrogen tank, and after the system is completely cooled, the superconducting tape is energized or excited. After the system is stable, a high-precision Hall sensor is used to measure the magnetic field on the surface of the superconducting tape. The movement of the Hall sensor in three-dimensional space is controlled by matlab code and realized by a three-dimensional path control system. The movement of the Hall sensor is controlled by the three-dimensional path control system to obtain more comprehensive magnetic field information. The electronic universal tensile testing machine can provide both static mechanical holding load and variable tensile load to achieve in-situ stretching. At the same time, the current loading system and the excitation magnet can apply the required current and magnetic field to the superconducting tape. The signal acquisition system can collect, process and analyze the measurement data in real time to provide more accurate measurement results.

[0050] The specific operation process of the superconducting tape magnetic field measurement device based on the Hall sensor in the embodiment of the present invention is as follows: fix the superconducting tape between the upper and lower clamps of the electronic universal tensile testing machine, pour liquid nitrogen into the liquid nitrogen low-temperature dewar, and after the system is completely cooled, energize or excite the superconducting tape. Set the tensile load according to specific needs, and after the system is stable, use a high-precision Hall sensor to measure the magnetic field on the surface of the superconducting tape. The movement of the Hall sensor in three-dimensional space is controlled by the matlab code and realized by the three-dimensional path control system. Figure 4 As shown, the specific steps are as follows:

[0051] (1) System alignment correction

[0052] The Hall sensor has a very high sensitivity to magnetic field measurement in space. Therefore, the principle of aligning all components with the three-dimensional path control system is adopted for calibration to achieve the required working accuracy of the Hall sensor. First, align the liquid nitrogen tank with the three-dimensional path control system and fix the liquid nitrogen tank (the lower fixture is fixed in the liquid nitrogen tank); secondly, align the upper and lower fixtures to ensure that they are in the same stretching line. In this way, the upper and lower fixtures are aligned with the three-dimensional path control system.

[0053] (2) Sample installation

[0054] Select a superconducting tape. Clamp it in the upper and lower clamps and use a laser measuring instrument to align the tape vertically (turn on the vertical laser of the measuring instrument and make it coincide with the edge of the tape). Finally, tighten the screws on the clamps to fix the tape.

[0055] (3) Mechanical load retention

[0056] Connect the positive and negative poles of the power supply to the power connectors of the upper and lower clamps of the electronic universal tensile testing machine through wires, and eliminate the mechanical influence of the wires on the upper and lower tensile clamps. After observing that there is no external force influence through the visual window of the tensile machine, clear all values ​​and enter the force closed loop interface, input 10N mechanical load to the tensile machine to ensure that the superconducting tape always remains stable during the subsequent cooling process.

[0057] (4) Hall sensor calibration

[0058] The Hall sensor is lowered from the three-dimensional path control system through the connecting rod, placed in a plane position parallel to the superconducting tape and fixed, and the Hall sensor is moved through the three-dimensional path control system. After the scanning area is determined according to the experimental requirements, the horizontal mark on the Hall sensor bracket is adjusted to the midpoint of the scanning area in the vertical direction, and then the vertical mark on the Hall sensor bracket is aligned with the middle position of the tape. Finally, the Hall sensor is adjusted to fit the superconducting tape.

[0059] (5) Cooling

[0060] After the system is calibrated, liquid nitrogen is poured into the liquid nitrogen tank and allowed to stand to allow the entire system environment to cool to the liquid nitrogen ambient temperature (77K).

[0061] (5) Current / magnetic field loading

[0062] For power-on scanning: First, check and calibrate all experimental equipment, including nanovoltmeters, signal acquisition cards, and superconducting power supplies. Ensure that all equipment is in normal working condition to ensure the accuracy of the experimental results. Connect all equipment to the current loading system correctly and ensure that the connection is stable and reliable. On the Labview operation interface, enter the quench criterion according to the experimental requirements. For superconducting tapes, the quench criterion is usually set to 10 -6 V / cm. This parameter is an important basis for judging whether the superconducting tape has quenched. When the quench criterion is reached, the power supply is cut off. After ensuring that the equipment is connected correctly, it is necessary to enter the current value to be passed in the operation interface of the superconducting power supply. According to the specific requirements of the experiment, select a suitable current value and ensure that it is within a safe range to avoid damage to the superconducting tape. Then pass the current at a constant speed. During the whole process, it is necessary to monitor the operating status of the equipment in real time and collect relevant parameters to ensure the smooth progress of the experiment.

[0063] For excitation scanning: the inspection and calibration steps of the experimental equipment are the same as above. For the excitation process: turn on the excitation magnet switch, change the magnetic field size by adjusting the external power supply, and adjust the current and voltage of the magnet according to the superconducting tape model and specific experimental requirements, thereby changing the size of the magnetic field provided by the magnet. The size of the magnetic field should be greater than 2 times the penetration magnetic field of the high-temperature superconducting tape.

[0064] (6) Adjusting the tensile load

[0065] Set the tensile load according to specific experimental requirements.

[0066] (7) Full-field scanning to measure magnetic field

[0067] After the entire system is stable, input the spatial range to be scanned and the moving speed of the Hall sensor, and perform full-field scanning to measure the magnetic field after determining the scanning accuracy (resolution). If an in-situ tensile test is performed, the tensile load needs to be reset after each scan before the next test.

[0068] The test results under in-situ tension are as follows:

[0069] 1. In-situ testing under power on

[0070] The superconducting tape model selected in the experiment is superpower SCS4050, with a width of 4 mm, a thickness of 0.1 mm, and a critical current of 103 A at 77 K. The surface magnetic field distribution of the superconducting tape under power-on conditions was measured under tensile loads of 10 N, 250 N, 320 N, 325 N, and 330 N.

[0071] Figure 5 The figure shows the magnetic field distribution of the superconducting tape under a 10N tensile load when the power is on. The x direction is the width direction of the tape, and the y direction is the length direction of the tape. It can be qualitatively seen from the figure that when the power is on, the magnetic field on the surface of the tape is evenly distributed along the length direction of the tape. The magnetic field distribution is anti-symmetrical about the central axis, and the magnetic field intensity reaches a peak around the tape boundary. As the distance from the tape boundary increases, the magnetic field gradually decreases to zero, and the attenuation rate of the magnetic field intensity along the tape boundary to the outside direction is much smaller than the attenuation rate of the magnetic field intensity along the tape boundary to the inner center direction. As the internal magnetic field intensity rapidly decays, a section of zero magnetic field intensity is generated in the middle.

[0072] Figure 6The magnetic field distribution of the superconducting tape under four different tensile loads when the power is on. The results show that with the increase of the tensile load, the distribution of the magnetic field on the surface of the superconducting tape changes significantly. Under low load conditions, the surface magnetic field distribution is relatively uniform, indicating that the superconducting tape has stable electrical conductivity in this state. However, with the increase of the tensile load, especially when the tensile load is close to the critical current degradation value, the distribution of the magnetic field on the surface of the superconducting tape becomes obviously uneven, and the magnetic field fluctuations on the surface of the tape are more obvious. This phenomenon may be related to the changes in the internal structure of the superconducting tape under the action of tensile stress. When the tensile load increases to a certain extent, the internal structure of the superconducting tape may be damaged, resulting in changes in its electrical conductivity, which in turn affects the distribution of the surface magnetic field.

[0073] Figure 7 The two-dimensional distribution diagram of the magnetic field distribution of the superconducting tape under different tensile loads when the power is on is similar to the three-dimensional diagram. Under the tensile loads of 325N and 330N, the magnetic field degradation is more obvious.

[0074] 2. In-situ test under excitation

[0075] The superconducting tape model selected in the experiment is superpower SCS4050, with a width of 4 mm, a thickness of 0.1 mm, and a critical current of 103 A at 77 K. The surface magnetic field distribution of the superconducting tape under excitation was measured under tensile loads of 10 N, 250 N, 320 N, 325 N, 330 N, and 335 N respectively.

[0076] Figure 8 The figure shows the magnetic field distribution of the superconducting tape under 10N tensile load under excitation. The x direction is the width direction of the tape, and the y direction is the length direction of the tape. It can be qualitatively seen from the figure that under excitation, the magnetic field on the surface of the tape is evenly distributed along the length direction of the tape. The magnetic field distribution is symmetrical about the central axis, and its magnetic field intensity reaches the maximum value around the tape boundary.

[0077] Fig. 9 The magnetic field distribution of the superconducting tape under different tensile loads under excitation conditions is shown in Figure 2. The results show that the distribution of the magnetic field on the surface of the superconducting tape changes significantly with the increase of the tensile load. With the increase of the tensile load, the distribution of the magnetic field on the surface of the superconducting tape becomes obviously uneven, and the magnetic field fluctuation on the surface of the tape is more obvious. When the tensile load increases to a certain extent, the internal structure of the superconducting tape may be damaged, resulting in changes in its conductive properties, which in turn affects the distribution of the surface magnetic field.

[0078] Fig.10The two-dimensional distribution diagram of the magnetic field distribution of the superconducting tape under different tensile loads under excitation, the law is similar to the three-dimensional diagram. Under the tensile loads of 325N and 330N, the magnetic field degradation is more obvious. Under the tensile load of 335N, the magnetic field is almost completely degraded.

[0079] The embodiments of the present invention have the following advantages:

[0080] 1. High-precision measurement: By using high-precision Hall sensors to measure the surface magnetic field of superconducting tapes, based on the high spatial resolution and high-precision magnetic flux density values ​​of the Hall sensors, the obtained magnetic field data is authentic and reliable with high accuracy, providing accurate magnetic field data for subsequent current density inversion, thus helping to optimize the performance and application of superconducting tapes.

[0081] 2. Multiple excitation modes: It can realize the excitation mode of superconducting tape under two working conditions: power on and excitation. This improvement overcomes the shortcomings of the single excitation mode of the existing invention and makes the measurement process more flexible and diversified.

[0082] 3. In-situ stretching: The superconducting tape can be stretched by applying different tensile loads, thus achieving in-situ stretching. This in-situ stretching helps analyze the electromagnetic behavior of the superconducting tape under different stress states, and improves the reliability and diversity of the measurement.

[0083] In summary, the advantages of the present invention are its high-precision measurement, multiple excitation modes and in-situ stretching functions, which help optimize the performance and application of superconducting tapes and improve the reliability and accuracy of measurements. It will also help to further analyze the electromagnetic field structure characteristics of superconducting tapes and the electro-magnetic-force multi-field coupling mechanism.

[0084] Embodiment 2:

[0085] The embodiment of the present invention further provides a method for measuring the magnetic field of a superconducting tape based on a Hall sensor, comprising the following steps:

[0086] Step 1, placing the clamp of the electronic universal tensile testing machine in a liquid nitrogen tank, and fixing the superconducting tape between the upper and lower clamps of the electronic universal tensile testing machine;

[0087] Step 2, controlling the movement of the Hall sensor in the three-dimensional space by a three-dimensional path control system to measure the magnetic field on the surface of the superconducting tape; wherein, the current loading system supplies power when power is turned on, and the excitation magnet provides the magnetic field when excitation is performed;

[0088] Step 3: Collect magnetic field data on the surface of the superconducting tape through a signal acquisition system, and monitor and record the magnetic field changes on the surface of the superconducting tape in real time;

[0089] Step 4: adjust the load acting on the superconducting tape by an electronic universal tensile testing machine to perform in-situ tensile deformation on the superconducting tape, repeat steps 2 and 3, and measure the electromagnetic behavior of the superconducting tape under different stress states.

[0090] As an implementation method of an embodiment of the present invention, a Hall sensor is composed of an external protective groove and an internal buried Hall chip; the Hall chip is composed of gallium arsenide, with geometric dimensions of 0.3mm×0.3mm×0.2mm, an active area diameter of 0.05mm, a frequency range of DC-1kHz, a full scale of 3T, an accuracy of ±0.2%, an operating temperature range of -269℃~+75℃, a temperature coefficient of 0.03% / ℃, an operating current of 2-5mA, and a sensitivity of 10mT / mV.

[0091] As an implementation method of an embodiment of the present invention, the scanning path of the Hall sensor is: starting from the middle position of the scanning length a to scan to the right half area, and then returning to the initial position in the middle of the strip to continue scanning to the left after completion, and after completing the scanning process of a straight line, moving upward from the left boundary area by a unit resolution along the b direction, and returning to the middle part of the second straight line to be scanned, completing a movement cycle, and repeating the next cycle until the entire a×b area of ​​the strip is scanned.

[0092] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A superconducting tape magnetic field measuring device based on Hall sensor, characterized in that: include: An electronic universal tensile testing machine, a high-precision Hall sensor, a liquid nitrogen tank, a current loading system and an excitation magnet; wherein the clamp of the electronic universal tensile testing machine is placed in the liquid nitrogen tank, the superconducting tape is fixed between the upper and lower clamps of the electronic universal tensile testing machine, the current loading system applies current to the superconducting tape when power is turned on, the excitation magnet performs excitation processing on the superconducting tape to provide a magnetic field when excitation is performed, and the high-precision Hall sensor is controlled by a three-dimensional path control system to perform point-by-point scanning and measurement of the magnetic field on the surface of the superconducting tape; The electronic universal tensile testing machine is used to perform in-situ tensile deformation on superconducting tapes. During the measurement process, the electromagnetic behavior of the superconducting tapes under different stress states is measured by adjusting the tensile rate and deformation of the electronic universal tensile testing machine. It also includes: a signal acquisition system for collecting magnetic field data on the surface of the superconducting tape, and monitoring and recording the magnetic field changes on the surface of the superconducting tape in real time; The Hall sensor is composed of an external protective groove and an internal buried Hall chip; the Hall chip is made of gallium arsenide, with geometric dimensions of 0.3mm×0.3mm×0.2mm, an active area diameter of 0.05mm, a frequency range of DC-1kHz, a full scale of 3T, an accuracy of ±0.2%, and an operating temperature range of -269℃~+75℃ ， The temperature coefficient is 0.03% / ℃, the operating current is 2-5mA, and the sensitivity is 10mT / mV; The scanning path of the Hall sensor is: start scanning from the middle position of the scanning length a to the right half area, and then return to the initial position in the middle of the strip to continue scanning to the left. After completing the scanning process of a straight line, move upward from the left boundary area by a unit resolution along the b direction, and return to the middle part of the second straight line to be scanned, completing a movement cycle, and repeating the next cycle until the entire a×b area of ​​the strip is scanned.

2. The superconducting tape magnetic field measuring device based on Hall sensor according to claim 1, characterized in that: The three-dimensional path control system uses OM motor two-phase single-axis stepper motors built in the x-axis, y-axis and z-axis directions to realize the movement of the Hall sensor bracket in three-dimensional space and measure the magnetic field in any area on the surface of the superconducting tape.

3. A method for measuring the magnetic field of a superconducting strip based on a Hall sensor, characterized in that: The following steps are involved: Step 1, placing the clamp of the electronic universal tensile testing machine in a liquid nitrogen tank, and fixing the superconducting tape between the upper and lower clamps of the electronic universal tensile testing machine; Step 2, controlling the movement of the Hall sensor in the three-dimensional space by a three-dimensional path control system to measure the magnetic field on the surface of the superconducting tape; wherein, the current loading system supplies power when power is turned on, and the excitation magnet provides the magnetic field when excitation is performed; Step 3: Collect magnetic field data on the surface of the superconducting tape through a signal acquisition system, and monitor and record the magnetic field changes on the surface of the superconducting tape in real time; Step 4: adjusting the load on the superconducting tape by an electronic universal tensile testing machine to perform in-situ tensile deformation on the superconducting tape, repeating steps 2 and 3, and measuring the electromagnetic behavior of the superconducting tape under different stress states; The Hall sensor is composed of an external protective groove and an internal buried Hall chip; the Hall chip is made of gallium arsenide, with geometric dimensions of 0.3mm×0.3mm×0.2mm, an active area diameter of 0.05mm, a frequency range of DC-1kHz, a full scale of 3T, an accuracy of ±0.2%, and an operating temperature range of -269℃~+75℃ ， The temperature coefficient is 0.03% / ℃, the operating current is 2-5mA, and the sensitivity is 10mT / mV; The scanning path of the Hall sensor is: start scanning from the middle position of the scanning length a to the right half area, and then return to the initial position in the middle of the strip to continue scanning to the left. After completing the scanning process of a straight line, move upward from the left boundary area by a unit resolution along the b direction, and return to the middle part of the second straight line to be scanned, completing a movement cycle, and repeating the next cycle until the entire a×b area of ​​the strip is scanned.

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