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P: Fachverband Plasmaphysik

P 24: Plasma Wall Interaction

P 24.3: Vortrag

Donnerstag, 16. März 2017, 09:15–09:30, HS 1010

Spectral Emission of Fast Non-Maxwellian Atoms at Metallic Surfaces in Low Density Plasmas — •Sven Dickheuer¹, Oleksandr Marchuk¹, Christian Brandt², and Albrecht Pospieszczyk¹ — ¹Forschungszentrum Jülich GmbH - Institut für Energie- und Klimaforschung - Plasmaphysik, Partner of the Trilateral Euregio Cluster (TEC), 52425 Jülich, Germany — ²Max- Planck-Institut für Plasmaphysik, 17491 Greifswald, Germany

We have observed Doppler-shifted emission of Balmer lines in hydrogen-argon mixed plasmas in a linear plasma (n_e ≈ 10¹¹ cm⁻³, T_i ≈ 2 eV). In pure hydrogen plasmas no Doppler-shifted emission above the signal-to-noise ratio could be measured [C.Brandt et al. O3.J107, EPS conference (2015)]. But in H-Ar mixed plasmas with a composition of 1:1 the intensity of Doppler-shifted emission reaches its maximum and the blue- and red-shifted components of the Balmer lines could be clearly detected. Different target materials (e.g. Ag, Pd, C) have been used to measure the dependence of the Doppler-shifted emission on the target material. The dependence of the emission on the target potential has been investigated by varying the target potential between − 30 V and − 220 V. Two possible processes could explain the observations of Doppler-shifted emission. The first one is the excitation by argon ground state Ar + H → (ArH)* → Ar + H*, the other one is the excitation transfer from the argon metastable state Ar* + H → (ArH)* → Ar + H*. Both possibilities are discussed in the talk and compared to the theoretical cross sections and measurements with other hydrogen-noble gas mixed plasmas.