München 2019 – scientific programme

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P: Fachverband Plasmaphysik

P 15: Helmholtz Graduate School V - Magnetic Confinement II

P 15.3: Talk

Wednesday, March 20, 2019, 12:00–12:25, HS 21

Edge fast-ion transport study using passive FIDA spectroscopy at ASDEX-Upgrade — •A. Jansen van Vuuren, B. Geiger, P.A. Schneider, A. Jacobsen, K. Mitosinkova, and The ASDEX-Upgrade Team — Max-Planck-Institut für Plasmaphysik, D-85748 Garching, Germany

Good confinement of fast-ions is mandatory in fusion plasmas since these supra-thermal particles are responsible for plasma heating and current-drive. However, instabilities and asymmetries in the magnetic field structure might redistribute fast-ions to unconfined orbits which is of particular importance for fast particles close to the plasma boundary.

A standard technique to obtain radial information on the fast-ion content is fast ion D-alpha (FIDA) spectroscopy, which measures the Doppler shifted Balmer alpha emission resulting from charge exchange reactions between fast ions and donor neutrals. On the one hand, donor neutrals are introduced by neutral beams causing so-called active FIDA radiation. On the other hand, thermal neutrals from the walls yield passive FIDA radiation which contains useful information on the fast-ion density close to the plasma edge.

This talk presents results based on the analysis of passive FIDA radiation. Background neutral densities are calculated with KN1D, with the passive D-alpha emission used as a constraint. Measurements from edge lines of sight show strongly reduced FIDA intensities after edge-localized modes. Forward modelling indicates a reduction in fast-ion density along the lines of sight, since the background neutral density is required to increase to match the passive D-alpha emission.