Hannover 2016 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 20: Poster Session- Low Temperature Plasmas

P 20.3: Poster

Mittwoch, 2. März 2016, 16:30–19:00, Empore Lichthof

Sticking probability for an electron hitting a dielectric surface — •Franz Xaver Bronold and Holger Fehske — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Deutschland

The energy of an electron hitting the wall of a low-temperature plasma is typically below 10 eV. In this energy range little is quantitatively known about the interaction of electrons with solids. For instance, the probability S with which the electron gets stuck in the wall is basically unknown. In plasma modeling S is thus very often set to unity, irrespective of the wall material (perfect absorber model for electrons). To study the material dependence of S we developed a method for calculating S from a microscopic model for the wall [1]. The method, based on an invariant embedding principle, expresses S as the probability for quantum-mechanical transmission through the wall’s long-range surface potential times the probability to stay inside the wall despite of internal backscattering. Besides emission of optical phonons and/or interband Coulomb collisions we take elastic scattering due to imperfections at the plasma-wall interface into account. Applying the approach to dielectrics with positive electron affinity, we obtain energy- and material-dependent sticking probabilities significantly less than unity, in accordance with available electron beam scattering data, but in disagreement with the perfect absorber model employed in plasma modeling. — Supported by DFG through CRC/Transregio TRR24.

[1] F. X. Bronold and H. Fehske, Phys. Rev. Lett. 115, 225001 (2015)