Design of Innovative Superconducting DC Cables

Abstract

Synopsis: We discuss the design of innovative superconducting DC power cables. The main point is the utilization of the longitudinal magnetic field effect; i.e., a large enhancement of the critical current density in a parallel magnetic field. For this purpose a parallel magnetic field is applied to the inner conductor of the cable by the current flowing back in the outside shield conductor. Superconducting tapes in the inner conductor are arranged in such a way that the force-free state is attained in the critical state under the given parallel magnetic field. The current-carrying capacity can be significantly improved by applying this geometry. However, the critical current density in existing commercial coated conductors does not increase in a parallel magnetic field due to weak links at grain boundaries. Then, a new cable structure is introduced to use the larger critical current density in a parallel magnetic field than that in a transverse magnetic field for commercial coated conductors. It is found that the current-carrying capacity can be appreciably increased from conventional cables and this design can also be applied to Bi-based superconducting tapes. Bean 2) Lorentz Fig. 1 Fig. 2 3) 46 force-free force-free Lorentz 0 Fig. 2 (1)