The transition of partial discharge to homogeneous discharge in nitrogen at low pressure

摘要

Homogeneous discharge is a hot topic with a lot of practical value in the field of plasma. With the change of gas condition (e.g. the gas pressure and composition etc.), a transition from partial discharge mode (or filamentary mode) to homogeneous discharge occurs. In this article, the surface charge behavior of the transition from filamentary mode to homogeneous mode was investigated. The dynamic surface charge distribution and discharge characteristics were measured by the surface charge measurement system based on Pockels effect. During the transition, the surface charge density decreases with decreasing gas pressure and the surface charge uniformity increases with decreasing gas pressure. The transition from filamentary to homogeneous discharge was achieved in nitrogen at 150 Torr. It is found that the transition from filamentary to uniform discharge was accompanied by an increasing probability of simultaneous discharge, and a uniform discharge is achieved when the discharge probability reaches a certain threshold. This result agrees with multiple electron avalanche coupling theory suggesting that the spatial overlap of avalanches leads to homogeneous discharge.