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P: Fachverband Plasmaphysik

P 16: Poster: Magnetischer Einschluss

P 16.11: Poster

Mittwoch, 1. April 2009, 17:30–19:30, Foyer des IfP

Effects of Strong Magnetic Shear Deformation in Tokamak Edge Turbulence — •Bruce Scott — Max-Planck-IPP, Euratom Association, Garching, Germany

Turbulence in the tokamak edge is studied using both gyrokinetic and gyrofluid models. The corresponding derivations and energy theorems have the same origin and ultimately represent at two different levels of sophistication the same model of low frequency electromagnetic dynamics. Magnetic trapping of electrons is found to strengthen the turbulence in the near-electrostatic regime, but both models show a strong rise of turbulent transport with plasma beta (magnetic inductivity) and they agree on its onset. This phenomenon is not found in the corresponding linear growth rates. A strong transfer of ExB eddy energy to longer wavelengths is measured. The scaling is nonlinear in origin and depends on amplitude maintenance of a shear-Alfvén component which has no role in the linear phases. Scaling against magnetic shear shows the breakdown of flux tube based coordinate systems for experimentally relevant (large) shear values. A new global field aligned treatment is developed to treat arbitrary shear. Gyrofluid and possibly also gyrokinetic turbulence results will be presented in shaped geometry.