Current redistribution under imbalanced condition in cable-in-conduit conductors

Cable-in-conduit conductors possess the possibility of nonuniform current distribution among strands. Any strand reaching the critical current may lead the whole conductor to the quench. However, current redistribution will play a major role in avoiding such a quench. In this paper, the enhancement of the normal-zone propagating current of a superconducting cable due to the current redistribution was studied experimentally. In the experiment, the current redistribution was confirmed, and the normal-zone propagating current, I_nzp of the cable became higher than the critical current of the strand. I_nzp has been investigated under several coolant conditions. As a result, I_nzp in liquid helium had the highest value compared with I_nzp in sub-cooled or supercritical helium. This difference clearly appeared by the usage of latent heat when the temperature of the strand rose.