Cryogenic Current Lead Optimization Using Peltier Elements and Configurable Cooling

Current leads for high-temperature superconductor transmission lines impose substantial heat load on the cryogenic system, in particular, for large-current short-distance transmission. Minimization of the heat load is challenging both at the designed operating current and during part load operation, particularly as the current is reduced towards zero. We examine the use of Peltier elements incorporated into current leads and propose the novel concept of configurable cooling to reduce the cryogenic heat load. The use of Peltier elements reduces the cryogenic load by at least 30%, as compared to normal metal leads. The configurable cooling concept uses multiple heat exchangers along the current leads to permit reoptimization of cooling conditions during reduced current operation. The combination of Peltier elements and configurable cooling can reduce the cryogenic load by up to a factor of four during low-current operation. Transient operation of current leads, with and without Peltier elements, and during overload conditions, is presented.