Hannover 2016 – scientific programme

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P: Fachverband Plasmaphysik

P 11: Poster Session- Plasma Wall Interaction

P 11.2: Poster

Tuesday, March 1, 2016, 16:30–19:00, Empore Lichthof

Emission of fast non-Maxwellian atoms at metallic surfaces in a linear magnetized plasma — •Sven Dickheuer, Oleksandr Marchuk, Christian Brandt, and Albrecht Pospieszczyk — Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung - Plasmaphysik, 52425 Jülich, Germany

The sheath between the unperturbed plasma and the plasma boundary plays a fundamental role in plasma research and is one of the most natural sources of fast non-Maxwellian atoms in plasmas. The considerable fraction of ions, accelerated in the sheath potential in front of an electrode, is reflected back as fast atoms. Recently we have observed fast D atoms in D-Ar mixed plasmas in the linear plasma device PSI-2. Studied by means of optical emission spectroscopy, the emission of fast D atoms appears in the spectrum as Doppler-shifted components of the Balmer-series [C.Brandt et al. O3.J107, EPS conference (2015)]. The Doppler-shift depends on the energy and particle reflection coefficients of the electrode material and its spectral reflectivity (roughness, e.g.). First results on the emission of fast H atoms for the target materials W, Fe, Pd, Ag and C are presented. We use a H-Ar mixed plasma and incident ion energies between ≈ 40 and 220 eV. The measurements are performed using lines-of-sights at different observation angles. The energy and angular distribution of the fast atoms are compared with the results from TRIM code calculations. In all cases, we have also obtained the data for the spectral reflection coefficient of the target materials. The results are tested against the reflectance measurements with light calibration sources and reference data.