Kiel 2004 – wissenschaftliches Programm

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P: Plasmaphysik

P 17: Postersitzung: Plasma-Wand-Wechselwirkung III, Grundlegende Probleme Theorie II, Schwerionen- Laserplasmen II, Dichte Plasmen II

P 17.6: Poster

Mittwoch, 10. März 2004, 17:45–19:30, Foyer

Relaxation of a collisonless ion matrix sheath — •Daniel Israel and Karl-Ulrich Riemann — Lehrstuhl für Theoretische Physik I, Ruhr-Universität Bochum, 44780 Bochum

An analytical fluid model describing the time evolution of a collisionless ion sheath in front of a plane absorbing wall biased to pulsed high negative voltage is presented. The model utilizes the Lagrangian formulation of hydrodynamics and allows to extend and generalize previous results [K.-U. Riemann and Th. Daube, J. Appl. Phys. 86, 1202 (1999)] for the matrix relaxation process obtained from the usual Euler formulation of hydrodynamics. Investigating the sheath evolution, the different phases of the matrix extraction and sheath expansion are characterized and treated separately. In addition, the transition between the two phases is investigated. Considering the matrix extraction phase, a description is developed, that in principle is suitable to account for arbitrary inhomogeneous initial conditions. Explicit results are given for two initial conditions of special interest. In order to describe the late quasistatic sheath expansion phase, the sheath boundary evolution is approximated and corresponding solutions are presented. The analytical results are compared with numerical solutions of the fluid equations as well as of PIC-MC simulations and show convincing agreement.