Optimization of termination for a high-temperature superconducting cable with a room temperature dielectric design

This paper describes the design considerations of a termination for a superconducting cable, based on tapes produced with the powder-in-tube method, with a room temperature dielectric design. Most important is the optimization of the current lead that leads the current from room temperature to cryogenic temperature. The current lead is optimized, using analytical as well as numerical methods. The paper proposes a current lead made of copper, with a constant cross-section area. With an optimized length-to-cross-section area ratio, the heat flow to the cold region is 43 W/kA for an uncooled current lead and 20 W/kA for a cooled current lead. The minimum loss in the entire termination is approximately 60 W/kA for a termination optimized for 2 kA. The paper describes why a gas-cooled current lead only reduces the total losses when used in connection with a multistep cooling machine.