Resistance of high-temperature superconducting tapes triggered by alternating magnetic field

TL;DR

This study investigates how alternating magnetic fields affect the dynamic resistance of high-temperature superconducting tapes, highlighting the impact of frequency, magnetic field, and modifications to the stabilizer on resistance and heating.

Contribution

The paper introduces a multilayer H-formulation model to calculate superconductor losses and examines the effects of stabilizer modifications on resistance under high-frequency magnetic fields.

Findings

Resistance increases significantly with frequency and magnetic field strength.

Modifications to the silver stabilizer influence the total resistance.

Losses cause heating and temperature rise affecting resistance measurements.

Abstract

Dynamic resistance occurs in a superconducting tape carrying a dc transport current while being exposed to an alternating magnetic field. This effect is caused by flux movements interacting with the transport current. The dynamic resistance is already applied in many superconducting applications, for example superconducting flux pumps or persistent current switches. The resistance is highly dependent on the magnetic field and the frequency the superconductor is subjected to and its properties. When the dynamic resistance exceeds a certain value and thus enters the magnitude of the resistances of the normal conducting layers of the HTS tape, these normal conducting layers play a significant role in the total resistance of the tape. In this paper, modifications were made to the silver stabilizer and the total resistance of the HTS tape has been investigated. The experimental results with frequencies up to 1000 Hz and magnetic field up to 277 mT show significant increases in resistance. Additionally, a multilayer model based on H-formulation is presented to calculate the losses of the superconductor. The results also show significant heating due to the losses and therefore a temperature rise, which effects the measured total resistance. These results can be further used for applications where high switchable resistances are required with zero dc resistance when the magnet is turned off.