Stuttgart 2012 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 13: Poster: Niedertemperaturplasmsen

P 13.3: Poster

Dienstag, 13. März 2012, 16:30–19:00, Poster.III

Secondary electron emission from dielectric surfaces due to de-excitation of impacting meta-stable nitrogen molecules — Johannes Marbach, •Franz Xaver Bronold, and Holger Fehske — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, D-17489 Greifswald, Deutschland

De-excitation of meta-stable molecules at the dielectric covering one of the electrodes of a dielectric barrier discharge is one of the main surface-based secondary electron emission channels controlling, together with wall recombination and various volume-based charge production and destruction processes, the overall charge balance and hence the operation mode of such a discharge. Secondary electrons, entering simulations of bounded plasmas via various secondary electron emission coefficients γ, strongly affect the results of the such simulations. Yet, little is quantitatively know about the γ coefficients. In our previous work [1] we set up a generic effective model for the underlying molecule-surface collision and used it to theoretically investigate Auger de-excitation of meta-stable nitrogen molecules at metallic surfaces. Now, with an eye on dielectric barrier discharges, we apply this model to dielectric surfaces where we find the de-excitation with subsequent electron release to be mediated by the shape resonance of the negative nitrogen ion. To calculate the associated γ coefficient we combine the Keldysh Green function technique used in [1] with rate equations. Numerical results are presented for Al₂O₃, MgO, and SiO₂ and discussed with respect to their implications for dielectric barrier discharges.

[1] J. Marbach et al., Phys. Rev. B 84, 085443 (2011).