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P: Fachverband Plasmaphysik

P 13: Theorie und Modellierung von Niedertemperaturplasmen I

P 13.1: Hauptvortrag

Donnerstag, 28. Februar 2013, 11:15–11:45, HS 3

Microphysics of charge transfer across the plasma wall — •Franz Xaver Bronold, Rafael L. Heinisch, Johannes Marbach, and Holger Fehske — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Deutschland

Plasma walls connect a discharge to the external circuitry and/or confine it in space. The walls act in both functionalities as charge reservoirs which donate and accept electrons to and fro the plasma. In the talk I will give an overview of our attempt to describe the charge transfer across the wall from a microscopic surface physics point of view. I will discuss electron deposition in terms of electron physisorption and introduce the concept of an electron-surface-layer as that part of the plasma sheath which leaks into the wall. Based on these ideas we calculated electron sticking coefficients and desorption times and determined the charge and potential distribution across the plasma-wall interface. I will also discuss electron extraction from the wall via recombination of positive ions and de-excitation of metastable species. In particular, I will show that a pseudo-particle description of the electronic states of the projectile within an Anderson-Newns-type model provides the basis of a flexible quantum-kinetic approach for the calculation of wall recombination and secondary electron emission coefficients. At the end I will argue that tracking electrons across the wall, that is, including the electronic degrees of freedom of the wall into the kinetic modeling of the discharge, may help to identify new vistas for dielectric barrier microdischarges. Supported by DFG through CRC/Transregio TRR24.