Kiel 2004 – wissenschaftliches Programm

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P: Plasmaphysik

P 20: Diagnostische Methoden V, Niedertemperaturplasmen Plasmatechnologie IV

P 20.5: Fachvortrag

Donnerstag, 11. März 2004, 12:10–12:30, H\"orsaal H

Townsend Discharge in a System with the High-ohmic Electrode — •Shalva Amiranashvili, Svetlana Gurevich, Lars Stollenwerk, and Hans-Georg Purwins — Institut für Angewandte Physik, Westfälische Wilhelms-Universität, Münster, Germany

Basic properties of Townsend (homogeneous) discharge are considered theoretically for a system with the high-ohmic electrode. The geometry is quasi-two-dimensional, e.g., the radial dimensions considerably exceed the distance between the electrodes. Such a choice is suggested by recent experimental studies of the sandwich-like discharge system with the metallic anode and the high-ohmic semiconductor cathode. The Maxwell time of the semiconductor is large as compared with the drift times of electrons and ions. A new time-scale is thus introduced for the surface charges on the cathode.

The discharge dynamics appears to more complicated than in the classical Townsend model with the metal electrodes. We discuss transverse stability of the uniform discharge and demonstrate the tendency to filamentary instabilities. It is possible to estimate the space-scale of the inhomogeneity and to compare results with the experimental data. Farther consequences of the surface charges dynamics are also discussed.