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P: Fachverband Plasmaphysik

P 6: Plasma-surface interaction

P 6.4: Vortrag

Dienstag, 10. März 2020, 12:10–12:25, b302

Ion-induced secondary electron emission coefficient of clean and dirty metal surfaces analysed in an ion beam experiment — •Rahel Buschhaus¹, Maik Budde², and Achim von Keudell¹ — ¹Experimentalphysik II, Ruhr-University Bochum — ²Department of Applied Physics, TU Eindhoven

In glow discharges the generation of secondary electrons at surfaces play an important role for ignition and maintenance of a plasma. The ion-induced secondary electron emission coefficient (iSEEC) γ depends on the chemical state of the surfaces and is defined as number of released electrons per incident ion. Depending wether metal surfaces are clean or dirty, e.g. oxidized, the γ coefficient varies [1]. The elementary plasma processes on surfaces are mimicked by sending quantified beams of ions to metal foils in an ultra-high vacuum reactor. Different thin metal foils are exposed to an ion beam of argon or metal ions, which are extracted from an inductively coupled plasma discharge (ICP). This ion beam is mass and energy selected (2eV-5keV) before reaching the metal foil. The unique feature of the here presented experiment is the possibility of analysis of surface processes induced by single and multiple ionized argon and/or metal ions and their oxides within a broad energy and mass range. For determination of the iSEECs a collector system based on current measurements is used [2]. We will present γ of different clean and dirty metal surfaces. The emission of electrons will be induced by either argon or metal ions within a broad energy range. [1] A. V. Phelps et al. Plasma Sources Sci. Technol. 8 R21 (1999) [2] A. Marcak et al., Rev. Sci. Instrum. 86, 106102 (2015)