Surface charge and photoionization effects in short air gaps undergoing discharges at atmospheric pressure

The discharge behaviour in short metallic-dielectric electrode gaps in air at atmospheric pressure is examined as a function of the surface charge density on a dielectric anode. The charge distribution is assumed to be Gaussian and calculations are carried out using a two-dimensional model with rotational symmetry. Discharge development shortly after discharge inception (t = 0.1 ns) is compared to that in proximity to discharge quenching (t = 1.0 ns). The results indicate that surface charge accumulation, as a consequence of successive discharges of like polarity, appreciably influences the photon flux at the cathode and the photoionization rate in the gas volume; it has a marked effect not only on the discharge behaviour at the longer development times but also shortly after discharge inception.