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Quench Detection Performance of Low-Temperature Superconducting Quench Detectors for REBCO Tape in Magnetic Fields

A quench detection method using a low-temperature superconducting quench detector (QD) has been proposed to protect rare-earth barium copper oxide (REBCO) coils at temperatures below 20 K in magnetic fields. In this study, we first conducted an experiment at 4.2 K in 0–9 T using a locally- degraded REBCO tape and Nb–Ti QDs (Nb–Ti/Cu, Nb–Ti/Cu–Ni). Quick quench detection before thermal runaway of the REBCO tape was demonstrated by the Nb–Ti/Cu–Ni QD in 0–9 T, whereas Nb–Ti/Cu QD exhibited quick quench detection only at 9 T. Furthermore, we numerically evaluated the quench detection time of Nb–Ti QDs attached to a REBCO tape with local degradation at 4.2 K in 0–9 T. The simulation reproduced the experimental results. Moreover, the contact resistance between the REBCO tape and QD should be lower than 1.0 × 10−3 m2K/W for quick quench detection.