Bremen 2017 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 11: Helmholtz Graduate School II
P 11.4: Vortrag
Dienstag, 14. März 2017, 15:15–15:40, HS 1010
Characterization of ELM associated phenomena by magnetic pick-up coils on ASDEX Upgrade — •Felician Mink1,2, Elisabeth Wolfrum1, Florian M Laggner1, Ulrich Stroth1,2, and The ASDEX Upgrade Team1 — 1Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany — 2Physik Department, E28, TUM, 85748 Garching, Germany
In highly confined tokamak plasmas periodically appearing edge localized modes (ELMs) are accompanied by mode-like magnetohydrodynamic (MHD) activities with defined toroidal mode numbers.
Here magnetic pick-up coil arrays are used to determine poloidal and toroidal mode numbers m and n of these inter-ELM modes and to calculate the variation of their amplitude with the poloidal angle, i.e. the ballooning. The radial position and the rotation velocity of the modes are estimated from m and n values and the measured frequency. Plasma parameters are varied in order to get an insight into the drive of these inter-ELM modes.
Several coexisting branches of modes at slightly different positions in the pedestal region are rotating with the vE× B dominated plasma velocity. Branches with low toroidal mode numbers, n=1−5, appear further outside and stronger ballooned than modes with intermediate ones, n=7−12. Mode numbers vary slightly with changing plasma parameters, but the strong ballooning is still only related to the low n modes, which are also conserved during the crash. These mode characteristics are in contradiction with the often mentioned kinetic ballooning modes.