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P: Plasmaphysik

P 10: Theory and Plasma Diagnostic (Poster Session)

P 10.4: Poster

Mittwoch, 4. April 2001, 12:30–15:00, AT2

Time-dependent electron kinetics in spatially one-dimensional plasma structures — •Detlef Loffhagen and Rolf Winkler — Institut für Niedertemperatur-Plasmaphysik, Greifswald, Germany

The spatiotemporal relaxation of electrons in the inhomogeneous column-anode plasma of glow discharges between plane electrodes is investigated. The studies have been performed by use of a newly developed, efficient method for solving the space- and time-dependent kinetic equation for the velocity distribution function of the electrons in two-term approximation. The resulting three-dimensional partial differential equation for the isotropic distribution is solved as an initial-boundary value problem over the space of the spatial coordinate and the total energy progressing in time. Results for the spatiotemporal evolution of electrons in inert gas plasmas acted upon by a constant electric field and initiated by a continuous flux of electrons into the plasma region at the cathode side are presented. Starting from an appropriate initial distribution, the electron relaxation is traced until the time-independent state is reached. Depending on the magnitude of the electric field, more or less pronounced spatial structures in the distribution function and related macroscopic quantities develop during the transient process. In particular, the electron mobility varies spatially between positive and negative values. The propagation of the structures takes place from the cathode side toward the anode and is mainly controlled by the mean electron transport velocity. The spatially structured, time-independent state is reached after a period which is considerably larger than the relaxation time to approach steady state in spatially uniform plasmas.