Hannover 2020 – scientific programme

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P: Fachverband Plasmaphysik

P 3: Low-temperature plasma and applications 1

P 3.5: Talk

Monday, March 9, 2020, 15:15–15:30, b302

Kinetic modeling of the electric double layer at the plasma-wall interface — •Kristopher Rasek, Franz Xaver Bronold, and Holger Fehske — Institut für Physik, Universität Greifswald, 17489 Greifswald

If a solid is in contact with a plasma an electric double layer forms, with a positive space charge in the plasma, the plasma sheath, and a negative space charge in the solid. We develop a kinetic model for such a double layer at a dielectric wall based on the Poisson equation for the electric potential and two sets of Boltzmann equations for the charge carriers in the plasma and the wall. By solving the Boltzmann and Poisson equations we are able to determine the full distribution functions of all carriers and with them quantities like charge profiles or photon emission rates. Expanding our previous work of the collisionless case [1], the collision integrals in the Boltzmann equations for the wall include both relaxation and (radiative or non-radiative) recombination of conduction band electrons and valence band holes. Using only material parameters such as the dielectric function and the band gap of the wall material, we determine the potential curve as well as the carrier distribution functions which are responsible for it. The emerging picture of our model is thus a floating dielectric surface where the potential profile across the double layer is the result of a selforganization process balancing electron-ion generation in the plasma and electron-hole recombination/relaxation in the solid.

[1] F. X. Bronold, H. Fehske, J. Phys. D: Appl. Phys. 50 (2017) 294003