The role of surface charge and its decay in surface dielectric barrier discharges

The charge accumulation and decay in surface dielectric barrier discharges (SDBDs) driven by a sine AC voltage waveform (4 kHz) in combination with a nanosecond positive voltage pulse (300 ns, 20 Hz) is experimentally investigated based on a combination of the electro-optical Pockels effect and a high-speed camera. It is found that the accumulation of positive surface charge on the dielectric promotes the discharge in the negative half cycle of the applied AC voltage, whereas it inhibits the development of following new positive charge filaments. The decay of a single positive charge filament on the surface is a result of the neutralization by negative charges that originate either from the migration of negative surface charge (electrons) or the drift of free electrons from the volume above the surface towards the surface. This work aims to contribute to a better understanding of the evolution of surface charge and its effects in SDBDs.