Erlangen 2018 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 13: Low Pressure Plasmas - Poster

P 13.5: Poster

Dienstag, 6. März 2018, 16:15–18:15, Redoutensaal

Quantum kinetic theory of ion-induced secondary electron emission from surfaces — Mathias Pamperin, •Franz Xaver Bronold, and Holger Fehske — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Germany

Secondary electron emission due to atomic species hitting the wall of a gas discharge is an important surface collision process strongly affecting the charge balance of the discharge. At impact energies typical for low-temperature plasmas electrons are ejected due to the transfer of the internal potential energy stored in the projectile’s electronic structure. To describe this process quantitatively we set up a general quantum-kinetic approach and applied it to an He⁺ ion hitting a metallic wall. Based on a semi-empirical multi-channel Anderson-Newns model, projection operator techniques, and the non-crossing approximation for the self-energies we derived rate equations for the occurrence probabilities of the projectile’s electronic configurations which may become operational in the course of the collision process. From it we also deduce the electron emission spectrum as a function of impact energy and angle. Auger neutralization of the positive ion as well as Auger de-excitation of radicals and/or negative ions, temporarily formed by single-electron transfers, are treated on an equal footing. For grazing incidence we get rather good agreement with experimental data indicating our approach captures the essential physics involved. Having in mind the tailoring of the electron emission spectrum by a judicious choice of the wall material we present results for various metals. – Supported by DFG through CRC/Transregio TRR24.