Self-pulsing of direct-current discharge in planar and curved geometries

Abstract

The self-pulsing of direct-current discharges in planar and curved geometries is studied using the two-dimensional axisymmetric fluid model. The simulation results show that in both cases the nature of self-oscillations is the same. They are obtained in the sub-normal mode of the discharge operation, for which the discharge has the negative differential resistance. We demonstrate that the negative differential resistance is due to both the non-linear and non-local dependence of the Townsend ionization coefficient on the electric field. We show that the self-oscillations are due to the ion transit time instability and are not related neither to RC resonance nor to the relation between the negative differential resistance and the ballast resistance as it is often suggested in the literature.