Superconducting Power Cable Design with Hybrid Cryogenic Media - Gaseous Helium for Cooling and Liquid Nitrogen for Dielectric Insulation

A novel design for high temperature superconducting (HTS) power cables is proposed to address the challenges of achieving low operating temperatures that support high power density and achieving high enough operating voltages. The design utilizes both cryogenic gaseous helium (GHe) and liquid nitrogen (LN2) as cryogenic media with different primary purposes. LN2 is used for its high dielectric strength and GHe is used primarily for cooling to support a low and wide operating temperature window. A novel Superconducting Power Cable with Hybrid Cryogens (SPCHC) is described along with the benefits of the design. A parametric study was performed to determine the necessary electrical insulation thickness needed for various operating voltages and conductor sizes. The results demonstrate a potential reduction of up to 95% in the volume of liquid nitrogen required for cables with 3 mm thick insulation, depending on the number of HTS conductors used, and the percentage of LN2 impregnation into the insulation layer of the cable. Challenges involved with achieving this promising reduction of LN2 volume and necessary future work for prototyping such a cable are discussed.