R. Morrow

CSIRO Division of Telecommunications and Industrial Physics
PO Box 218, Lindfield NSW 2070, Australia
richard.morrow@tip.csiro.au

Theoretical results are presented for the filamentary discharge that develops between two electrodes separated by a dielectric barrier which prevents the dc flow of current in the gas. Such discharges, in gas at atmospheric pressure, are used in a wide range of applications; for example, in rare gases, and rare gas halide gas mixtures, excimer radiation of various UV wavelengths can be generated. In flu gases, reactions can be stimulated to remove NOx and SOx pollutants. While in electrical insulation such discharges in voids can lead to the breakdown of high-voltage systems. Two-dimensional results are presented for the development of an electron avalanche near the cathode which crosses the gap to distort the electric field near the anode. The distortion of the electric field near the anode results in an ionising wave, or streamer, which rapidly moves back towards the cathode, bridging the gap to the cathode where a cathode fall region forms. Eventually the insulators charge up, and the voltage across the gap falls until the discharge stops. In practice ac voltage is applied, and the discharge reverses each cycle. The continuity equations for electrons, positive ions, and negative ions (if present), are solved using a new two-dimensional FCT algorithm together with a two-dimensional solution of Poisson's equation using an SOR method. Then spatial and time dependent predictions are made of the electric field, which is crucial for the prediction of specific chemical processes.