Darmstadt 2008 – scientific programme
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P: Fachverband Plasmaphysik
P 7: Magnetischer Einschluss II
P 7.2: Talk
Tuesday, March 11, 2008, 17:25–17:40, 2E
3D Equilibrium Calculations of TEXTOR like discharges with resonant magnetic perturbations — •Christopher Wiegmann1, Joachim Geiger2, Yasuhiro Suzuki3, Detlev Reiter1, and Robert Wolf2 — 1Institut für Energieforschung - Plasmaphysik, Forschungszentrum Jülich GmbH, Assoziation EURATOM-FZJ, Trilateral Euregio Cluster, D-52425 Jülich — 2Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald — 3National Institute for Fusion Science, Toki, Oroshi-Cho 322-6, Japan
Experiments using resonant magnetic perturbations (RMPs) to influence the plasma edge gained much interest on several tokamaks. The TEXTOR tokamak has a special set of perturbation coils (dynamic ergodic divertor) allowing for various operation scenarios. To study transport and MHD properties in the plasma edge it is necessary to provide the underlying 3D equilibrium field structure. Up to now, the magnetic field was obtained by superposing a 2D equilibrium field with the vacuum perturbation field ("vacuum approximation"). Experimental studies on plasma footprints at target plates show that this approximation gives good agreement in the m/n=12/4 mode while there is strong disagreement in the 3/1 case (even excitation of 2/1 tearing modes). Furthermore, application of a screening factor due to plasma rotation shows significant changes in the magnetic topology. We discuss these effects and present the status of calculations with the 3D ideal MHD equilibrium code HINT2, allowing for magnetic islands and ergodic regions. These calculations are aiming to clarify the parameter window when the vacuum approximation is applicable.