Point-to-plane discharge dynamics in the presence of dielectric droplets

Abstract

The effects of dielectric liquid droplets on the electrodynamics of the streamer-induced discharges under high voltage pulses in a non-uniform electric field are investigated in air at atmospheric pressure. Owing to electrical and optical correlated measurements, changes in the properties of streamer development have been described. It has been shown that a jet of droplets can have a guiding action and a velocity increase effect on streamer advancement, as well as a reduction of the voltage range where streamers develop. The streamer threshold potentials are globally higher when droplets lie close to the positive point electrode and the critical potentials beyond which a streamer leads to an arc development are significantly lower when discharges are driven by the droplets jet. While calculations with a three-dimensional electrostatic solver show that a local field enhancement near the droplets could help to explain these effects, a supplementary interpretation should be the extraction of electrons from the droplets surface by photons emitted from the positive streamer front.