Static and dynamic breakdown characteristics of cryogenic liquids for electrical insulation design of superconducting power apparatus

We investigated the quench-induced dynamic breakdown characteristics of liquid helium (LHe) for various post-quench thermal energy, gap lengths and pressures of LHe under both non-uniform and uniform electric field. Experimental results revealed that the dynamic breakdown voltage increased with decreasing the post-quench thermal energy and with increasing the gap length and pressure, because of the suppression of thermal bubble disturbance in LHe. All of the experimental data enabled us to establish the 3-dimensionally systematized diagram of dynamic breakdown voltage of LHe as functions of post-quench thermal energy, gap length and pressure.