Kiel 2011 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 2: Magnetischer Einschluss I
P 2.4: Fachvortrag
Montag, 28. März 2011, 17:45–18:10, HS C
Fast-Ion D-Alpha measurements at ASDEX Upgrade — •Benedikt Geiger1, Manuel Garcia-Munoz1, Rainer Fischer1, William Heidbrink2, Rachael McDermott1, Giovanni Tardini1, and and the ASDEX Upgrade team1 — 1Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching, Germany — 2University of Irvine, Irvine, California, USA
The confinement of fast ions (ions with energies significantly above the thermal energy) is essential in fusion devices because they contribute to plasma heating and current drive, but can also damage the first wall if poorly confined. To study the distribution function of fast ions in the ASDEX Upgrade tokamak (AUG) a fast-ion D-Alpha (FIDA) diagnostic has been developed. It uses 25 radially distributed lines of sight to measure Doppler shifted D-Alpha radiation, emitted from neutralized fast ions. The diagnostic's toroidal geometry determines a well defined region in velocity space which significantly overlaps with the typical fast-ion distribution in AUG plasmas. As first results of the newly commissioned diagnostic, radial FIDA intensity profiles during on- and off-axis NBI are presented. These show changes in the radial fast-ion distribution function with the different neutral beam injection geometries. Good agreement has been obtained in MHD quiescent plasmas by comparing the measurements to simulations using calculated fast-ion distribution functions from TRANSP. In addition, MHD events have been observed such as Alfven waves, which flatten the observed radial fast-ion profiles, and a q=2 sawtooth like crash, which redistributes about 50% of the central fast-ion population.