We confine the nanosecond repetitively pulsed discharge (NRP) 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 1×10 19 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.

plasma-enhanced hydrogen and hydrocarbon flames [6,7], and atmospheric pressure Ar and He plasma jets [8,9]. This non-intrusive measurement technique yields time-resolved and spatially resolved electric field vector components, with sub-ns temporal resolution, providing insight into kinetics of ionization wave formation and propagation, charged species transport, and energy partition in transient non-equilibrium plasmas. This technique is highly sensitive, simple to use,

When a sufficient high voltage is applied between a point and a plate in atmospheric air, a corona discharge is ignited and an electrohydrodynamic (EHD) force can be produced, resulting in an ionic wind of a few meters per second flowing from the point toward the plate. In this study, we aimed at characterizing the ionic wind EHD flow produced by DC positive point-to-plate corona discharges. This is realized with the help of a high-speed particle image velocimetry system and Schlieren visualizations. The obtained measurements allowed us to characterize precisely the ionic wind vs time, as well as its dynamics when the discharge is switched on. We highlighted the key role of the breakdown streamers in the ionic wind hydrodynamics. We discovered that, in the presence of breakdown streamers, the positive corona discharge produces a pulsed ionic wind whose frequency corresponds to the frequency of the current pulses. To explain this EHD result, we investigated and showed that each single current pulse is composed of several streamers or several branches of one streamer, this phenomenon being at the origin of a space charge mainly composed of positive ions. Finally, we highlighted that when the steady breakdown streamer regime takes place, the time-averaged current becomes greater than the theoretical values given by Townsend's law since it evolves nearly linearly with the high voltage.