Double-pulse streamer simulations for varying interpulse times in air

TL;DR

This study uses fluid simulations to analyze how double-pulse streamer discharges in air are affected by interpulse timing, revealing different regimes of streamer behavior and relating them to physical parameters.

Contribution

The paper introduces a detailed simulation analysis of double-pulse streamers, identifying regimes and relating streamer continuation to dielectric relaxation and electron detachment processes.

Findings

Streamer continuation occurs within a specific interpulse time window.

Electron densities at streamer continuation match previous experimental data.

Electron detachment reactions slow electron density decay for interpulse times over 100 ns.

Abstract

In this paper, we study how streamer discharges are influenced by a previous voltage pulse using an axisymmetric fluid model. We simulate double-pulse positive streamers in N2-O2 mixtures containing 20% and 10% O2 at 1 bar. By varying the time between the pulses between 5 ns and 10 microseconds, we observe three regimes during the second pulse: streamer continuation, inhibited growth and streamer repetition. In the streamer continuation regime, a new streamer emerges from the tip of the previous one. In the inhibited regime, the previous channel is partially re-ionized, but there is considerably less field enhancement and almost no light emission. Finally, for the longest interpulse times, a new streamer forms that is similar to the first one. The remaining electron densities at which we observe streamer continuation agree with earlier experimental work. We introduce an estimate which relates streamer continuation to the dielectric relaxation time, the background field and the pulse duration. Furthermore, we show that for interpulse times above 100 ns several electron detachment reactions significantly slow down the decay of the electron density.