Calculation of critical current in DC HTS cable using longitudinal magnetic field effect

Abstract

It is known from experimental data that the critical current of superconducting wires in a longitudinal magnetic field is higher than that in a transverse magnetic field. This property was proposed to apply to DC superconducting cables in our previous paper. Here, we propose a new calculation method of the current-carrying capacity for a new DC superconducting cable. An iteration method is used to calculate the magnetic field and critical current density in each layer and the current-carrying capacity of the cable. This enables us to calculate these quantities even for the cable with a different structure from the force-free one. When the critical current density increases with a longitudinal magnetic field, the optimal structure is found to be close to that of the force free cable. The optimal structure is obtained also when the critical current density decreases slightly with the longitudinal magnetic field. The reason for the enhanced current-carrying capacity even for such a case is a sufficiently larger critical current density in the longitudinal magnetic field than that in the transverse magnetic field.