Magneto-thermal stability analysis of Nb3Sn multifilament superconducting wires in rotating magnetic fields

Abstract

Superconducting wires in superconducting motors typically operate in environments with strong magnetic fields and high currents, which may trigger flux jumps accompanied by rapid temperature rises. This can lead to a decrease in the wire’s current-carrying capacity and even result in a quench. In this study, the Nb₃Sn superconducting wire, consisting of multiple superconducting filaments and copper, was modeled by constraining the net current of each filament to be zero in order to simulate the three-dimensional twisting characteristics. The magneto-thermal stability of the superconducting wire under rotating magnetic fields was investigated. The effects of the magnetic field amplitude and frequency on the flux jump behavior of the Nb₃Sn superconducting wire were analyzed. As the magnetic field amplitude increased, the frequency range of flux jumps initially increased and then decreased. We examine the effect of different ratios of rotational to alternating fields $k$ on flux jumps. At lower frequencies, the number of flux jumps increased with $k$, at higher frequencies, the number of flux jumps initially increased and then decreased. Subsequently, the effects of the Cu/SC ratio and the number of filaments on flux jumps were studied. For a fixed frequency, the number of flux jumps and the temperature rise exhibited non-monotonic variations with the magnetic field amplitude. When the magnetic field amplitude fixed, both the number of flux jumps and the temperature rise decreased with increasing frequency. Finally, the variation in the number of flux jumps with the Cu/SC ratio and $k$ was discussed.