Simulation of negative-streamer dynamics in nitrogen.

Abstract

In this paper we consider how the dynamical characteristics of streamers are determined by their multidimensional structure. Results from two-dimensional (three-dimensional, cylindrically symmetric) simulations are presented at atmospheric pressure for ${\mathrm{N}}_{2}$ and plane-parallel electrodes. Our high-spatial-resolution simulations are based on a numerical model which is able to treat a wide range of electrode configurations (including point-to-plane and other complex configurations). This model has allowed us to make a more thorough investigation of streamer morphology than has been attempted previously. Detailed knowledge of the streamer morphology and its evolution are vital to the application of streamer discharges to processes such as the destruction of airborne toxic chemicals. We find that the morphology is complex, even for plane-parallel electrodes, with a range of radial structures that become evident at different phases of the streamer evolution. Several distinct phases of evolution are clearly discernible. We demonstrate the transition between these phases, showing how the self-consistent radial and axial structure varies with time.