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
m
²
K/W for quick quench detection.