Thermal anchoring of conduction-cooled current leads for superconductivity applications near liquid nitrogen temperature

As the YBa2Cu3O7–δ, or YBCO, superconductor is commercially developed and utilized for various HTS (high temperature superconductor) applications such as motor, generator, and fault current limiter, the cryocooling for 50 or 60 K range is more demanded than ever. In this case, non-superconducting current leads instead of HTS ones need to be used for energization from room temperature all the way to the cryogenic operating temperature. This technical note describes a simple method of reducing cooling load requirement for those HTS applications. Non-superconducting current leads are to be thermally anchored at an appropriate intermediate cryogenic temperature before they are connected to the application target temperature. The optimum thermal-anchoring temperature and its configuration have been obtained to minimize the required cryocooler’s cooling capacity for practical as well as ideal cases.