3HASSOUBA M A, ELAKSHAR F F, GARA- MOON A. Measurements of the breakdown po- tentials for different cathode materials in the townsend dischange[J]. Fizika A, 2002,11 (2) : 81-90.
4HAAARRNAN R A, WILLIAMSON K D. Electrical breakdown and tracking characteristics of pulsed high voltages in cryogenic helium and ni- trogen [J]. Advances in Cryogenic Engineering, 1975, 21(3): 20-24.
5MEATS R J. Pressurized helium breakdown at very low pressures[J]. Proc IEEE, 1972, 119 (6) : 35-38.