Critical current measuring method, system and medium of superconducting material

Abstract

The invention provides a critical current measuring method, system and medium of a superconducting material. The method comprises the steps of time-varying current loading, wherein time-varying current is connected with a sample; magnetic field measuring, wherein a sensor of an inductive coil is arranged at a preset position, and the magnetic field distribution around the sample is measured through the sensor to obtain measurement information; critical current judgment, wherein according to the obtained measurement information, whether or not the sample reaches a critical current state is judged, the moment when the sample reaches the critical current in the time-varying current loading step is judged, and the critical current of the sample is obtained. Through a short sample experiment, under the situation that the current is much larger than the critical current of the sample (a current of 550 A is connected in a sample with a critical current of 300 A), the experiment is repeated several times, and the burnout of the sample is avoided.

Description

technical field [0001] The invention relates to the field of superconducting materials or applied superconducting, in particular to a critical current measurement method, system and medium of superconducting materials. In particular, it relates to a method for inductively measuring the critical current of a superconducting material using a pulse current, so as to realize the measurement of the critical current of the non-ideal second-type superconductor. Background technique [0002] 1. Superconductors and critical current [0003] It is the biggest characteristic of superconducting materials to enter the superconducting macroscopic quantum state in which the resistance becomes zero at low temperature. In response to this peculiar phenomenon, people have proposed many fantastic applications in the field of strong electricity such as electricity and magnets. However, the real application of superconducting materials to unimpeded high-density current transmission is about 50...

AI Technical Summary

Problems solved by technology

However, for users, there is an important defect that the measurement results of the induction method are not direct enough to achieve sufficient reliability. There are two reasons for this problem. The first is that in the induction method, the superconducting current is often in the form of circulating The form exists, and its flow is very different from the way it flows from one end to the other in a real application

The second is that the more complex calculation and analysis are designed in the induction method, and it is inevitable that errors will occur during the derivation process. In fact, the most common method in the induction measurement is to compare with the transmission measurement, and then use a correction parameter to correct various measurements. As a result, such a measurement method is far less convincing than direct energization; and the most important problem of the transmission method is that the input power is too high, and there is a risk of burning the sample, and the contact current lead cannot be directly welded in the long strip measurement. Resistive heating further exacerbates the risk of burning the strip. In addition, the measurement speed of the transmission measurement method is worrying. It is not realistic to measure the high-resolution critical current at the 1cm level.

Even in currently unoptimized devices, it takes longer than the DC transfer method

[0011] It must be pointed out here that due to the inductive voltage caused by the current change during the pulse process, and the resistive voltage signal to be measured is very weak, which seriously affects the speed of pulse measurement

In principle, a shorter pulse can speed up the measurement time and reduce the risk due to the reduced Joule heating, but the inductive voltage is an important limitation of the pulse transmission measurement. In order to exclude the influence of the inductive voltage, the duration of the flat-top pulse has a minimum Limit (usually on the order of 10ms)

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