Optimization of a superconducting gas-insulated transmission line

The superconducting gas insulated transmission line (S-GIL) is a new design being proposed for helium gas (GHe) cooled high temperature superconducting (HTS) power cables. The S-GIL design utilizes GHe as both cryogen and insulation medium for the HTS cable. This paper builds upon previous proof of concept measurements of the S-GIL. Through optimization of the S-GIL design parameters increase of 20–30% in electrical breakdown voltages was observed for the proof of concept measurements. The paper also contains details on a prototype S-GIL design which was adopted from a commercial coaxial air dielectric cable. The prototype S-GIL cable was successfully demonstrated at 77 K using both GHe and 4 mol% H2 balanced with GHe as the cryogen/insulation medium. The values obtained by the prototype S-GIL cable are higher than the voltage rating currently capable of other GHe cooled HTS cables which verifies the potential of the S-GIL design concept.