Ionization and recombination in nanosecond repetitively pulsed microplasmas in air at atmospheric pressure

We confine the nanosecond repetitively pulsed discharge to the micrometer scale, in a 200 µm discharge gap in air at atmospheric pressure and room temperature, focusing on measurements of the electron number density and electron temperature. The Stark broadening of H, O and N atomic lines and electrical conductivity both show that the electron number density reaches a maximum value of 1  ×  10¹⁹ cm⁻³. Boltzmann plots show the electron temperature to be 72 kK several nanoseconds after the end of the pulse of applied electric field. We will use these results to determine the mechanism responsible for electron loss during the early recombination phase (t  <  500 ns) and comment on the degree of ionization and dissociation. (paper)