Pressure Dependence of Dielectric Breakdown in Liquid Nitrogen

Abstract

Breakdown voltage characteristics in liquid nitrogen (liq.N 2 ) have been studied in the pressure range between 1 and 15 atm. For constant gap length, the breakdown voltage increases with increasing pressure and saturates at around 10 atm. For shorter pulse width, the increase in breakdown voltage with pressure becomes less remarkable. In a non-uniform field of a plane-needle electrodes system, the breakdown voltage of the negative needle configuration increases remarkably with increasing pressure but that of the positive needle is almost insensitive to the pressure. These results can be interpreted in terms of the suppression of the formation and the development of a gaseous bubble in the breakdown of liq.N 2 under high pressure and at short pulse width. The positive streamer seems to play an important role in initiating total breakdown under high pressure and at short pulse width.