Time-Resolved Measurements of Electron Density in Nanosecond Pulsed Plasmas Using Microwave Scattering

TL;DR

This study uses microwave scattering to measure how electron density in nanosecond pulsed air plasmas varies with gap distance and time, revealing rapid decay due to recombination.

Contribution

It demonstrates a novel application of Rayleigh microwave scattering for time-resolved electron density measurements in pulsed plasmas.

Findings

Electron density peaks at 10^17 cm^-3 during breakdown.

Electron density decreases with increasing gap distance.

Decay occurs over microseconds due to recombination.

Abstract

In this work, Rayleigh microwave scattering was utilized to measure the electron number density produced by nanosecond high voltage breakdown in air between two electrodes in a pin-to-pin configuration (peak voltage 26 kV and pulse duration 55 ns). The peak electron density decreased from 1*10^17 cm^-3 down to 7*10^14 cm^-3 when increasing the gap distance from 2 to 8 mm (total electron number decreased from 2*10^13 down to 5*10^11 respectively). Electron number density decayed on the timescale of about several microseconds due to dissociative recombination.