CN201110876Y - High-temperature superconducting material superconductivity test system - Google Patents

Abstract

The utility model relates to a high-temperature superconducting material superconductivity testing system, which comprises a gradient amplifier whose output is connected with a sample to be tested and a protection resistor to form a main circuit; a Hall current sensor is arranged in the main circuit to measure the effective value of the current The industrial control computer is equipped with a data acquisition card to provide control signals for the main circuit to control the entire measurement process, and process and save the collected data; the stretching machine is used to stretch the sample to be tested to complete the stress Strain measurement; lock-in amplifier, to measure the axial voltage at both ends of the sample to be tested and the phase angle between voltage and current; isolation preamplifier, to isolate the strong current from the weak current and amplify the voltage signal; And the isolation amplifier is used for isolation between strong current and weak current. The utility model can separately complete three performance tests of the critical current, the AC loss and the stress and strain of the high-temperature superconducting material, and has high degree of automation, accurate measurement, high efficiency and rapidity.

Description

High-temperature superconducting material superconductivity test system

technical field

The utility model relates to a superconductivity testing system for high-temperature superconducting materials.

Background technique

At present, the critical current, AC loss, and stress-strain properties of high-temperature superconducting materials have become important technical indicators for the engineering application of superconducting materials, so it is particularly important to accurately measure these three properties. The traditional testing technology is to test the three separately, and most of the tests are manual or semi-automatic, and it takes a lot of time from the test preparation to the end of the test each time; and the superconducting strip itself is a fragile item, if the sampling is not appropriate It is easy to cause the fracture of the superconducting core and lead to the degradation of the critical current, so we should try to avoid this situation during the test.

Utility model content

The purpose of this utility model is to provide a superconductivity testing system for high-temperature superconducting materials, which can respectively complete the tests of the critical current, AC loss, and stress-strain performance of high-temperature superconducting materials, and solve the problem of automation of traditional testing devices. A trivial and time-consuming problem.

In order to achieve the above object, the utility model adopts the following technical solutions:

The utility model discloses a superconductivity testing system for high-temperature superconducting materials, which includes a sample to be tested and a protective resistor, and is characterized in that the system also includes

A gradient amplifier, the output of which is connected to the sample to be tested and the protection resistor to form a main circuit;

A Hall current sensor is arranged in the main circuit to measure the effective value of the current;

An industrial control computer, equipped with a data acquisition card, provides control signals for the main circuit to control the entire measurement process, collects the current output of the Hall current sensor and the voltage signal at both ends of the sample to be tested, and processes the collected data and save. The voltage signal at both ends of the sample to be tested is output to the data acquisition terminal of the computer after passing through an isolation preamplifier.

The system also includes a stretching machine controlled by the computer to stretch the sample to be tested to complete the measurement of stress and strain.

The system also includes a lock-in amplifier to measure the axial voltage at both ends of the sample to be tested and the phase angle between the voltage and the current. Its signal output terminal is output to the gradient amplifier after passing through an isolation amplifier, and its signal input terminal is respectively connected to Hall The current output of the current sensor and the voltage signal at both ends of the sample to be tested, and the lock-in amplifier is connected to the computer through a serial port.

Due to the adoption of the above scheme, the utility model has the beneficial effects that: the tests of the critical current, AC loss, and stress-strain properties of the high-temperature superconducting material can be completed separately, with high degree of automation, accurate measurement, high efficiency and rapidity.

Description of drawings

Fig. 1 is a structural schematic diagram of critical current measurement;

Fig. 2 is a structural schematic diagram of transmission loss measurement;

Fig. 3 is the structural representation of stress-strain measurement;

Figure 4 is a flow chart of the test system.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described further.

Example 1

A high-temperature superconducting material superconductivity testing system, as shown in Figure 1, includes a sample to be tested and a protective resistor, and the system also includes a gradient amplifier whose output is connected to the sample to be tested and the protective resistor to form a main circuit;

A Hall current sensor is arranged in the main circuit to measure the effective value of the current;

An industrial control computer, equipped with a data acquisition card, provides control signals for the main circuit to control the entire measurement process, collects the current output of the Hall current sensor and the voltage signal at both ends of the sample to be tested, and processes the collected data and save. The voltage signal at both ends of the sample to be tested is output to the data acquisition terminal of the computer after passing through an isolation preamplifier.

The measurement principle of the critical current: The critical current is measured by the standard four-lead method. The voltage control signal is generated by the analog output channel of the data acquisition card, and the gradient amplifier is controlled to generate a current rising slowly from zero in the superconductor. The magnitude of the current is detected by the Hall current sensor and entered into the computer by the input channel of the data acquisition card. The voltage is amplified 40,000 times by the isolation preamplifier and then enters the computer through the input channel of the data acquisition card. The voltage criterion of 1 μV/cm is adopted, that is, when the electric field strength of 1 μV/cm appears in the strip, the current value in the sample at this time is the critical current of the superconductor.

Example 2

A high-temperature superconducting material superconductivity testing system, as shown in Figure 2, includes a sample to be tested and a protective resistor, and the system also includes a gradient amplifier whose output is connected to the sample to be tested and the protective resistor to form a main circuit;

A Hall current sensor is arranged in the main circuit to measure the effective value of the current;

An industrial control computer, equipped with a data acquisition card, provides control signals for the main circuit to control the entire measurement process, collects the current output of the Hall current sensor and the voltage signal at both ends of the sample to be tested, and processes the collected data and save.

The system also includes a lock-in amplifier to measure the axial voltage across the sample to be tested and the phase angle between the voltage and current. The signal output terminal of the lock-in amplifier is output to the gradient amplifier after passing through an isolation amplifier. The isolation amplifier plays the role of isolation and impedance matching, which not only realizes the current source, but also ensures the isolation of the power amplifier. The signal input terminals of the lock-in amplifier are respectively connected to the current output of the Hall current sensor and the voltage signals at both ends of the sample to be tested, and the lock-in amplifier is connected to the computer through a serial port.

电流信号的大小Irms可由霍尔电流传感器和数据采集卡采集得到，这样样品的传输损耗

就测出来了。其中轴向电压的有效值Vrms和相角

是最为关键的两个量，测量难度也非常大，一方面Vrms极小，为10^-8V到10^-6V之间；同时还必须准确的测量电压和电流之间的相角

本套测试系统的搭建满足了对这两个量的准确测量。Measuring principle of strip transmission loss: The measuring process is controlled by computer. The computer and the lock-in amplifier are connected through a serial port. First, the OSC of the lock-in amplifier is controlled to output a sinusoidal signal of a certain frequency f and amplitude (such as 50Hz, 1V). The current signal Irms with the same frequency f, this current flows through the superconducting sample, and the loss voltage Vrms is generated on the sample, the magnitude of the loss voltage Vrms and the phase (relative to the internal reference signal of the lock-in amplifier) measured by the lock-in amplifier, the phase of the current signal Irms (relative to the internal reference signal of the lock-in amplifier) is measured by the Hall current sensor and the lock-in amplifier. So the phase difference between the current and voltage signals

The size Irms of the current signal can be collected by the Hall current sensor and the data acquisition card, so that the transmission loss of the sample

It was measured. Among them, the effective value Vrms and phase angle of the axial voltage

They are the two most critical quantities, and the measurement is very difficult. On the one hand, Vrms is extremely small, between 10 ^-8 V and 10 ^-6 V; at the same time, the phase angle between voltage and current must be accurately measured

The construction of this test system satisfies the accurate measurement of these two quantities.

Example 3

A high-temperature superconducting material superconductivity testing system, as shown in Figure 3, includes a sample to be tested and a protective resistor. The system also includes a gradient amplifier whose output is connected to the sample to be tested and the protective resistor to form a main circuit;

A Hall current sensor is arranged in the main circuit to measure the effective value of the current;

An industrial control computer, equipped with a data acquisition card, provides control signals for the main circuit to control the entire measurement process, collects the current output of the Hall current sensor and the voltage signal at both ends of the sample to be tested, and processes the collected data and save. The voltage signal at both ends of the sample to be tested is output to the data acquisition terminal of the computer after passing through an isolation preamplifier.

The system also includes a stretching machine controlled by the computer to stretch the sample to be tested to complete the measurement of stress and strain.

During the manufacturing process of Bi2223 superconducting equipment, the superconducting strip will be subject to stress such as bending, tension, compression and torsion; during the operation of the superconducting magnet, the superconducting strip will also be subjected to the Lorentz force of the magnetic field; During the operation of the conductive transmission cable, it will also be affected by its own field Lorentz force; during the cooling process, the superconducting core will also be affected by thermal shrinkage stress. Therefore, during the fabrication and operation of superconducting devices, superconducting materials are inevitably subjected to stress/strain. Therefore, it is extremely important to consider the degradation of critical current under stress and strain. Stress-strain measurement principle: that is, to apply a certain stress to the superconducting strip, and measure the magnitude of the strain and the magnitude of the critical current under the stress at the same time, and the magnitude of the applied stress gradually increases until the critical current is completely degraded, and finally according to The corresponding curves are drawn out of the results, which provide a solid data basis for the process of superconducting cables.

The biggest advantage of this utility model is its high integration. For the above three kinds of superconductivity, we have made a corresponding software with VB6.0 language. Through this software, the above three kinds of properties can be accurately measured without measuring separately.

Claims (4)

1. The superconductivity testing system for high-temperature superconducting materials, including samples to be tested and protective resistors, characterized in that the system also includes A gradient amplifier, the output of which is connected to the sample to be tested and the protection resistor to form a main circuit; A Hall current sensor is arranged in the main circuit to measure the effective value of the current; A computer with a data acquisition card inside to provide control signals for the main loop to control the entire measurement process, collect the current output of the Hall current sensor and the voltage signal at both ends of the sample to be tested, and process and save the collected data . 2. The superconductivity testing system for high-temperature superconducting materials according to claim 1, wherein the voltage signal at both ends of the sample to be tested passes through an isolation preamplifier and then is output to the data acquisition terminal of the computer. 3. The high-temperature superconducting material superconductivity testing system according to claim 1 or 2, characterized in that: the system also includes a stretching machine, controlled by the computer, to stretch the sample to be tested to complete the stress Strain measurement. 4. The high temperature superconducting material superconductivity testing system according to claim 1, characterized in that: the system also includes a lock-in amplifier to measure the axial voltage at both ends of the sample to be tested and the phase angle between the voltage and the current , the signal output terminal is output to the gradient amplifier through an isolation amplifier, the signal input terminal is respectively connected to the current output of the Hall current sensor and the voltage signal at both ends of the sample to be tested, and the lock-in amplifier is connected to the computer through a serial port.

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