Erlangen 2018 – scientific programme
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P: Fachverband Plasmaphysik
P 16: Low Pressure Plasmas II
P 16.4: Talk
Wednesday, March 7, 2018, 15:00–15:15, KI 1.174
Dissociative recombination and its impact on the line profile of the hydrogen Balmer series — •Roland Friedl1, David Rauner1,2, and Ursel Fantz1,2 — 1AG Experimentelle Plasmaphysik, Universität Augsburg, 86135 Augsburg — 2Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching
In low pressure low temperature plasmas the upper levels of the Balmer series of the hydrogen atom are populated by several excitation channels. Among them, dissociative recombination (DR) via the molecular ion H2+ becomes relevant—up to dominant—in so-called recombining plasmas, e.g. in a diffusive region of H2 plasmas. Detailed analysis of the measured emission line profile of the Balmer series furthermore revealed a significant broad component. The resulting line profile resembles two Gaussian components with distinct FWHM, where the broad part contributes to 10–40 % to the emissivity, depending on the Balmer line and the plasma conditions. Collisional-radiative modeling using the code Yacora H (Wünderlich et al., JQSRT 110 (2009) 62) was applied in order to determine the contribution of the different excitation channels. It turned out, that for each of the lines of the Balmer series, population via DR contributes to the total excitation with a similar share as the share of the broad component of the line profile. Hence, strong indications are given that DR accounts for the broad component in the Balmer line profiles of recombining hydrogen plasmas.