Monte Carlo simulation for development of electron avalanches in nitrogen at moderate and high reduced electric field

Abstract

This paper addresses the simulation of electron avalanches in nitrogen by means of the Monte Carlo method. The data have been obtained for the conditions of classical measurements of the impact ionization coefficient in a wide range of reduced electric fields E/p. It is shown that at moderate E/p values, the results are in a good agreement with the generally accepted approaches in the description of the avalanches based on the drift motion of the electrons and on the diffusion. The high E/p is achieved in the vicinity of the minimum of Paschen's curve due to decreasing the gas pressure. Then the process of development of the single electron avalanche changes radically. The reason is that the runaway electrons appear, which leads to essential longitudinal expansion of the electron cloud. It is revealed that the average electron energy at the front of the cloud turns out to be larger than that at the backside of the cloud.