Possibility of ac applications of high-T c superconductors in a flux-flow state

Abstract

For the ac applications of high-Tc superconductors, the possibility of a ‘‘flux-flow conductor’’ is proposed. The ac loss of a high-Tc superconductor in the flux-flow state is theoretically examined. Two applications, a power transmission cable and a winding of an ac coil, are considered. The ac loss of a ‘‘flux-flow superconducting cable’’ may become smaller than that of a ‘‘critical state cable’’ in ordinary conditions, because the upper critical fields of high-Tc oxides are large. On the other hand, the ac loss of a ‘‘flux-flow ac superconducting wire’’ becomes advantageous only in a limited condition, namely, high frequency, low current density, and low magnetic field.