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

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.

Theoretical model and experimental investigation optically triggered hollow-cathode discharge formation

“…However, equation (1) describes the model of a typical parallel-plane discharge-gap configuration and it does not account for the influence of 'seed electrons'. As shown in [15], the total ionization cross-section in the hollow-cathode region is one order of magnitude higher than that of the main gap during the pre-breakdown phase. The cathode's aperture and the hollow-cathode configuration lead to the formation of a reduced E/N region (E/N represents a reduced electric field, where E is an electric field and N is the density of neutral particles) in the hollow cathode and promote substantial ionization events here, due to potential lines penetrating into the cathode region.…”

“…The HCD device and the PIC calculationdomain model are illustrated in figures 1(a) and (b), which are the same as the experimental setup in section 2. The gas used is Ar and the gas pressure is 50.6 mTorr in the simulation, while the other simulation parameters including the cell size, time step, initial density for tracked particles, particle weight, and secondary coefficient are the same as those used in [15] and are shown in table 1. Figures 1(c) and (d) are the electronphase plots and potential distributions at 4 kV and 10 kV, illustrating that the potential lines penetrate more deeply and widely inside the hollow-cathode region under higher applied voltages.…”

Low-pressure discharges with hollow cathode and hollow anode and their applications

“…Interpretation of the processes in the stage of the delay time to breakdown have been carried out in numerous papers [2,12,14,[64][65][66][67][68][69]. The physical model for the low-pressure discharge formation at the prebreakdown stage has been proposed and developed in [2,12,14].…”

Characteristics of Pseudospark Discharge in Particle-in-Cell Simulations

“…Later particle-in-cell (PIC) simulation was used to take into account the motion of the electrons in the plasma field more accurately [15]. Since then more simulations were carried out to investigate the impacts to the discharge current and breakdown time from different discharge parameters, including the pressure of the background gas and the dimensions of the discharge cavity [16,17].…”