Two-dimensional electron density measurement of pulsed positive primary streamer discharge in atmospheric-pressure air

Abstract

Elucidating the electron density of streamer discharges propagating in atmospheric-pressure air is critical for achieving a systematic understanding of the production mechanisms of reactive species. Using Shack–Hartmann-type laser wavefront sensors with a temporal resolution of 2 ns, we carried out single-shot two-dimensional electron density measurements for positive primary streamers generated in a 13 mm air gap between pin-to-plate electrodes. The electron density over the positive primary streamers decayed from 1015 to during the propagation. The decay time constant of the electron density in the primary streamer channels was estimated to be ∼2 ns. The distribution widths of the electron density were in good agreement with those of the light emission, typically ranging from 0.8 to 1.5 mm.