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P: Plasmaphysik

P 10: Theory and Plasma Diagnostic (Poster Session)

P 10.26: Poster

Wednesday, April 4, 2001, 12:30–15:00, AT2

Electron Kinetics in the Anode Region of Glow Discharges — •Stefan Arndt, Dirk Uhrlandt, and Rolf Winkler — Institut für Niedertemperatur-Plasmaphysik, Greifswald, Germany

The two-dimensionally space-dependent electron kinetics in the anode region of a cylindrical glow discharge is studied. The anode region represents a typical interaction region of a plasma and a conducting surface which absorbs electrons. It has to be described as the transition region from the axially uniform and radially non-uniform positive column to the equipotential anode surface. Under low-pressure and low-current conditions, the plasma properties are mainly determinated by the non-local behaviour of the electrons. The relevant Boltzmann equation of electrons is solved in two space dimensions. The solution method is based on the two-term expansion of the velocity distribution. Finally, a three-dimensional initial boundary value problem has to be treated. Beside appropriate boundary conditions describing e.g. the electron absorption at the anode, an axial electric field, which starts with the constant axial field in the positive column and increases in front of the anode, and the action of a radially increasing radial space charge field are taken into account. The space- dependent description allows among others to investigate the influence of the electron absorption at the anode as well as the impact of the anode fall on the spatial structure of the electron kinetic properties close to the anode. Furthermore, the axial and radial particle and energy fluxes of electrons in the anode region can be determinated due to the rigorous kinetic character of the description. Detailed results are presented for neon discharges at pressures around one Torr.