High Speed Quench Propagation of Forced Flow Cooled Superconducting Coil

Abstract

Cable-in-conduit type forced flow cooled superconductor (CICC) has many strands in a conduit. It has attractive characteristics of stability, insulation and mechanical rigidity, etc. Its hydraulic diameter is, however, relatively so small that pressure rise will be large at quench. By the way, attractive characteristics has been found out. It is that the normal zone propagates with high speed in some condition, which will help the stored energy been consumed in large area and reduce temperature gradients. We discuss this high speed quench propagation. We made a forced flow cooled superconducting coil with a CICC. The CICC was 12m long and the test coil was a solenoidal coil with 0.3m diameter. Each turn was apart from each other. We can neglect heat conduction between each turns, so that the test coil is an ideally one dimensional model. We measured the propagation speed at quench in 6.5T magnetic field, and compared them with numerical simulation results. They agree well, including the high speed quench propagation characteristics.