The role of fast electrons in diffuse discharge formation: Monte Carlo simulation

Abstract

In this paper, we report on results from a computational investigation of nanosecond pulsed discharges in air of negative polarity using a two-dimensional fluid and fluid-Monte Carlo simulations. The computational parameters and conditions are taken from an experiment. The discharge is initiated near the cathode having a small radius of curvature and propagates towards the flat anode. The simulations are done in atmospheric pressure air with a nanosecond pulse of 120 kV amplitude in a 12 mm gap with a sharp cathode. The essential difference between discharges initiated by low-and high-energy beams of electrons originating in the vicinity of the cathode was observed. The beam of electrons with the initial energy of 20 keV was shown to result in a diffuse discharge, while the 20 eV beam had a negligible influence on the discharge evolution. By analyzing the experimental and computational results, we conclude that a diffuse discharge is formed due to fast electrons without any assumptions on the critical role of the runaway electrons. More study is required to explore the intermediate range of energies and investigate the transition to the diffuse mode of the discharge.

Effect of photoionisation on initial discharge in air under nanosecond pulse voltage

“…Particle-in-cell and Monte Carlo collisions (PIC/MCC) models are usually used to research electrons with high energy. Some of the models do not take into account photoionisation [19][20][21][22], assuming it has a little effect on the initial discharge stage, while others do [23][24][25] and might think that its impact should not be ignored. So far, there is a lack of investigation on whether the photoionisation affects the development (or evolution) and electron runaway of the initial discharge in atmospheric air under nanosecond pulse voltage.…”

Влияние Скорости Волны Ионизации На Напряжение В Линии При Развитии Импульсного Пробоя

“…Начальная стадия развития импульсного пробоя перенапряженного промежутка с сильно неоднородным электрическим полем сопровождается формированием пучка убегающих электронов [1][2][3][4][5][6][7][8][9][10]. За этим пучком следует волна ионизации, которая представляет собой резкий градиент концентрации заряженных частиц в направлении ее движения.…”

Duration of runaway electron current pulses when applying voltage pulses with a subnanosecond rise time

“…Much attention is paid to the study of the parameters of RE beams in laboratory discharges at high pressures of air and other gases, as well as X-ray radiation under the influence of a RE beam (REB) [8][9][10][11][12][13][14][15][16][17][18][19]. A significant part of these studies is carried out under conditions of breakdown of centimeter-sized gaps with abrupt cathodes filled with air at atmospheric pressure.…”

“…Both the current parameters of the REB under various conditions and the mechanism of generation of RE are studied. Studies are also carried out by modeling discharges with RE, see, for example, [9][10][11]15,[20][21][22].…”