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

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.