Hannover 2020 – scientific programme
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P: Fachverband Plasmaphysik
P 5: Poster Session 1
P 5.18: Poster
Monday, March 9, 2020, 16:30–18:30, Empore Lichthof
Fast-ion confinement studies in W7-X using active Balmer-alpha spectroscopy — •Peter Zs. Poloskei1, Benedikt Geiger2, Oliver Ford1, Simppa Äkaslompolo1, Annabelle Spanier1, and the W7-X team1 — 1Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, Greifswald, Germany — 2University of Wisconsin, Madison, USA
Investigation of fast-ion transport in fusion plasmas plays a central role as good fast-particle confinement is essential for burning plasmas. For its recent experimental campaign, the W7-X stellarator was equipped with two neutral hydrogen beam injectors (NBI) which provide fast-particles of our interest and neutral hydrogen particles which make active Balmer-alpha spectroscopy possible.
Due to the complex shape of the measured spectra forward modelling is required for its interpretation. It is done with a code called FIDASIM which takes into account different assumed kinetic plasma profiles, fast-ion densities and information of the beam- and observation geometry.
It was found that most measured spectral components are well reproducible with FIDASIM but the observed active emission, coming from the beam neutral - confined fast-ion charge-exchange reaction (FIDA) cannot fully explain the measured intensities. This suggests that fast-ions in the plasma edge region could interact with the cold neutral population from the plasma vessel, causing additional passive FIDA emission. This needs to be understood in order to address the question of edge charge-exchange fast-ion losses and to infer information on the edge neutral density.