Dependence of pre-breakdown time on ionization processes in a pseudospark discharge

Xiaotong Cao,Weijie Huo,Ruixue Zhang,Wansheng Zhao,Yulei Fu,Jing Hu

doi:10.1063/1.5003242

Abstract

The formation and development of pseudospark discharge, especially the onset of the breakdown, are of great technological interests in multiple applications due to their influences on the limits of current rising and fast switching performances of the devices. In this work, the development of pseudospark discharge in the pre-discharge and hollow cathode phases in a single-gap device are investigated by a time-dependent model to calculate the temporal development of total ionization cross section in varying times and regions. The simulations in our work are performed using the two-dimensional kinetic plasma simulation code XOOPIC. The time-dependent evolutions of the ionization cross section in pre-discharge and hollow cathode phases are presented under varying electric fields and hollow cathode configurations. Thus the electron multiplications and plasma generation processes by ionizing collisions in varying phases are examined and their dependences on a variety of external parameters are determined in different regions in the pseudospark device. A sequence of physical events and their influences in different regions are also identified via the quantitative analysis of time-dependent ionization cross section. The discharge formation time shows highest dependences on the cathode aperture diameters and anode voltages. Additionally, a linear dependence of the pseudospark breakdown time on the time-averaged ionization cross section is illustrated under varying external parameters. It indicates that the influences of the external parameters on the discharge performances can be determined and estimated via the total and average ionization cross sections under varying external conditions. In this work, both a qualitative understanding of the pseudospark onset mechanism and a quantitative approach to estimate the formation time in a pseudospark device with varying parameters are developed via this model.

Highlights

The pseudospark discharge, operating at the low pressure regime located on the left hand side of the Paschen curve, was first discovered in 1970s
The basic configuration of a pseudospark device consists of a pair of plane electrodes, with an axial bore hole located on the discharge gap and a hollow cavity behind the cathode electrode
A single-gap pseudospark device with featured discharge gap and hollow cathode is developed as the simulation model

Summary

Introduction

The pseudospark discharge, operating at the low pressure regime located on the left hand side of the Paschen curve, was first discovered in 1970s. The basic configuration of a pseudospark device consists of a pair of plane electrodes, with an axial bore hole located on the discharge gap and a hollow cavity behind the cathode electrode. With such a configuration the pseudospark discharge is capable of generating tens to hundreds kV hold-off voltage and kA discharge current during total pulse duration of tens to hundreds ns and rise time of several ns. These transient characteristics make it suitable for a diversity of applications, especially for the pulsed switch applications[1,2] and oscillators.[3,4] the increasing technological interests in the development of pulsed power devices require further understanding of the fundamental processes,which govern the build-up and development of the discharge and already are the main focus of a number of research work.

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