Electrical model and analysis of the transition from an atmospheric pressure Townsend discharge to a filamentary discharge

This work is a contribution to the understanding of the mechanisms controlling the transition from a Townsend to a filamentary dielectric barrier discharge when the power increases. The approach consists in developing an electrical model of the discharge and the power supply to study the interaction between these two elements. The main components of the discharge model are (i) two Zener diodes whose characteristics depend on the power to take into account the effect of the gas density variation induced by the temperature variation and (ii) a RC circuit describing the memory effect from one discharge to the following one which is due to the metastables and the electrons trapped on the surface of the solid dielectrics. The calculated and measured currents are very similar over all the range of amplitude and frequency allowing to get an atmospheric pressure Townsend discharge. The model also describes the transition to filamentary discharge observed when the excitation frequency increases too much showing that it is due to a very fast variation of the load connected to the power supply. From this understanding, a solution is deduced to increase the maximum power dissipated in the discharge which consists in decreasing the solid dielectric capacitance.