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P: Plasmaphysik

P 10: Theory and Plasma Diagnostic (Poster Session)

P 10.25: Poster

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

Study of a DC Column Plasma in a Longitudinal Magnetic Field — •Dirk Uhrlandt¹ and Rolf Winkler² — ¹ — ²Institut für Niedertemperatur-Plasmaphysik, Greifswald, Germany

The impact of a superimposed longitudinal magnetic field on the column plasma kinetics in a cylindrical dc glow discharge is investigated. A comprehensive, fully self-consistent model of the column plasma has been used to determine the kinetic quantities of electrons, ions and excited atoms, the radial space charge field and the axial electric field for given discharge conditions. The model includes a nonlocal kinetic treatment of the electrons by solving their spatially inhomogeneous kinetic equation taking into account the radial space charge potential and the magnetic field. This treatment is based on the two-term expansion of the velocity distribution and comprises the determination of its isotropic and anisotropic components in the axial, radial and azimuthal direction. As an example a neon dc discharge at 75 Pa and a discharge current of 10 mA in a tube with the radius of 1.7 cm has been studied. Main findings of this study are: The electron kinetic behavior, which is distinctly nonlocal in that example without a magnetic field, changes to a local behavior by increasing the magnetic field up to a field strength of about 200 Gauss. In close correlation to this evolution at first, a slight increase of the axial electric field with the magnetic field has been found. Then the axial field and the wall potential decrease with a further increase of the magnetic field due to the intensified plasma confinement.