Spike voltages seen during quick charge ramp limitation tests on Nb3Sn cable-in-conduit conductors

Abstract

Spike voltages observed during ramp rate limitation tests on sub-sized Nb3Sn cable-in-conduit superconductors are analyzed using a current loop model. The effects of loop currents on the ramp rate limitations of multi-strand superconducting cables are discussed. Current existing in multistrand cables generate excess local currents that quench strands and produce voltage spikes. Experimental results previously reported as abnormal ramp rate limitations are explained by loop current phenomena.