Simulation of the stable ‘quasi-periodic’ glow regime of a nanosecond repetitively pulsed discharge in air at atmospheric pressure

Abstract

This paper presents simulations of the dynamics of nanosecond repetitively pulsed discharges between two point electrodes in atmospheric pressure air at 300 and 1000 K. At 300 K, the preionization left by successive discharges at the end of interpulses mainly consists of positive and negative ions with a density of about 10 9 cm −3 for a repetition frequency of 10 kHz. When photoionization is taken into account with a level of seed charges of about 10 9 cm −3 , the dynamics and the characteristics of the discharge during a voltage pulse are shown to depend only weakly on the nature of negative seed charges (electrons or ions). At 1000 K, the preionization left by successive discharges at the end of interpulses consists of positive and negative ions and electrons with a density of about 10 10 cm −3 for a repetition frequency of 10 kHz. Simulation results show that the dynamics and the characteristics of the discharge during a voltage pulse remain rather close whatever the preionization level considered in the range 10 9 -10 11 cm −3 , corresponding to nanosecond repetitively pulsed discharges in the frequency range 1-100 kHz. The simulation of several consecutive nanosecond voltage pulses at a frequency of 10 kHz shows that, at 1000 K, the discharge can reach in a few voltage pulses a stable 'quasi-periodic' glow regime in agreement with experiments. Finally, the influence of an external air flow aligned with the electrode axis on the conditions to obtain a stable 'quasi-periodic' glow regime is discussed.

Repetitively pulsed gas discharges: memory effect and discharge mode transition

“…Nagaraja et al [80] developed an integrated theoretical and numerical framework and provided temporal evolution and dynamics of chemical kinetics, energy coupling, gas heating, and generation of active particles excited by long‐term repetitive pulses in low‐pressure air ( t pw : 3 ns, PRF: 1–100 kHz, consecutive pulse number: up to 100 pulses). Tholin and Bourdon [22, 23, 81, 82] systematically simulated external factors on the development of repetitively pulsed nanosecond discharges ( t pw : 12 ns, PRF: 1 Hz–100 kHz, consecutive pulse number: up to 7 pulses), including the background gas temperature, hydrodynamics expansion, and external circuit impedance. As illustrated in Fig.…”

“…Progressive breakdown/flashover mechanisms under long‐term repetitive pulses have not been fully revealed, specifically why the initial corona discharge eventually triggers catastrophic breakdown/flashover in the pre‐breakdown stage and what the insulation thresholds are at a long‐term operation. Despite the fact that the progressive ‘corona–glow–spark’ transition is frequently observed under long‐term repetitive pulses [16, 22–24], a reversed transition from the spark to diffusive discharge has been reported [25]. The real‐time tracking and actively confining desired discharge modes are technically challenging, especially the temporal integration of complex memory effects in the long‐term operation and the bounds of discharge instabilities are unclear.…”

The inception of pulsed discharges in air: simulations in background fields above and below breakdown

“…In addition, streamers play an essential role in natural discharges, since they pave the path for lightning and sprites. They have been studied in different gases and in different electric field configurations both experimentally [8,9,10,11,12,13,14] and numerically [15,16,17,18,19,20,21,22,23,24].…”

A ‘frozen electric-field’ approach to simulate repetitively pulsed nanosecond plasma discharges and ignition of hydrogen–air mixtures

“…Consequently, the electrical dynamics during a burst of nanosecond discharge pulses may exhibit periodic behaviours for low flow velocities and in the absence of significant variations in the gas number density or mixture composition. Tholin et al [14] observed similar behaviour in their 2D simulations of pulsed nanosecond discharges in a pin-pin geometry at 1 atm pressure. The plasma reached a 'quasi-periodic' glow regime with repetitive application of voltage waveforms.…”

“…High-fidelity NRPD simulations can be immensely beneficial in understanding the complex electric-field dynamics and in quantifying the key kinetic pathways for active species production and their ensuing chemical reactions. There have been significant efforts in developing self-consistent models of nanosecond discharges for various applications [5,6,[11][12][13][14]. In this context, self-consistency refers to the numerical solution of the coupled system of equations for the electric potential, charged and neutral species continuity and flow dynamics, without any adjustable parameters.…”