Current-carrying capability of the 100 kA-class HTS STARS conductor for the helical fusion reactor FFHR-d1

Abstract

A 100-kA-class conductor using REBCO high-temperature superconductor (HTS) is proposed as one of the conductor options for the helical coils of the LHD-type helical fusion reactor FFHR-d1. We named it STARS (Stacked Tapes Assembled in Rigid Structure) conductor. Current carrying capability of such a simply-stacked tape conductor is an important issue. We fabricated and tested a 100-kA class STARS prototype conductor sample to verify whether a premature quench occurs. The conductor sample is a one-turn short-circuit coil with a race-track shape having a bridge-type mechanical lap joint. The transport current of the sample was induced by changing the external magnetic field, and the critical current of the sample was measured. A numerical analysis of the critical current is being performed by self-consistently solving the spatial distributions of the current density and magnetic field among the tapes to verify the measured critical current of the samples.