Understanding Surface Flashover Strength in Cryogenic Helium Gas for Superconducting Devices

One of the limitations when developing GHe cooled HTS devices for power applications is determining suitable insulation designs. There would be significant reductions in cost, time, and effort if insulation designs could be accurately measured and characterized at room temperature instead of cryogenic temperatures. Our previous research on the intrinsic breakdown strength of GHe demonstrated that it is independent of temperature, and it is solely based on the mass density of the gas. However, the insulation of HTS power devices contains solid insulation materials, and it is necessary to confirm that the interaction between the solid insulation and GHe is also independent of temperature. This paper contains the development and fabrication of a surface flashover experiment setup which can be used at both room and cryogenic temperatures to characterize surface flashover in a GHe environment.