In modern superconducting systems high-temperature composites replace traditional low-temperature superconductors in particular integral part of devices such as superconducting energy storage [1], current limiters [2], MRI [3]. HTS switching in such systems occurs through the generation of nonequilibrium states, as usual under a pulsed current, magnetic or local thermal effect [4]. In the case of pulsed current effects, the transition from the superconducting to the resistive state is due to the excess of the critical current of the superconductor. Modeling of nonequilibrium states arising in superconductors under single or combined current influences is necessary for the design switching devices. Short current pulses are of particular interest.

 This paper presents the results of FEM modeling of an HTS tape under the action of short ( ~1 μs) and long ( ~10 ms) current pulses. Modeling and analysis of the dynamics of electrophysical processes occurring in the HTS composites are carried out taking into account the influence of local thermal processes in the structure of the composite, in particular, in the presence of inhomogeneities of the critical current distribution and influences of the superconducting tape layer. The HTS composite switching time from the superconducting to the normal state were investigated for different amplitudes of current pulses up to 3.3Ic and different rise times of the front of the action. An experimental verification of the numerical model has been carried out. The simulation was carried taking in account cooling by liquid nitrogen, hysteresis character of the boiling curve. It is shown that with effective cooling, local bursts of heat release can be successfully evacuated by a liquid coolant or compensated by cryogenic equipment. In this case, there are no fundamental restrictions on the use of currents that significantly exceed the critical current of HTS.

The reported study was funded by RFBR according to the research project № 17-29-10024

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2. Dong Keun Park et al. // IEEE Trans. Appl. Supercond. 2009. Vol. 19, № 3. P. 1896–1899.
3.Kim S.B. et al. // Phys. Procedia. 2015. Vol. 65. P. 149–152
4. M. Zhang et al, 2017 Supercond. Sci. Technol. 30, 024005 (pp.7)

Keywords: HTS tape, switching, short current pulse, modeling