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P: Fachverband Plasmaphysik

P 13: Magnetic Confinement

P 13.6: Poster

Dienstag, 14. März 2017, 16:30–18:30, HS Foyer

Shearing rate dependence of turbulent transport — •Til Ullmann and Mirko Ramisch — Institute of Interfacial Process Engineering and Plasma Technology, University of Stuttgart

In toroidally confined fusion plasmas, poloidal E× B shear flows play a crucial role in the reduction of radial turbulent transport Γ. Theoretical predictions exist for the functional dependence of Γ on the shearing rate on a rational surface and close by. In order to test the transport’s shearing rate scaling, plasma biasing via a ring electrode is used at the stellarator TJ-K for controlling the shearing rate Ω of imposed stationary flows. The applicability of this method could already be demonstrated: Ω generally increases with bias voltage. In a next step, the cross-field transport is calculated from data of a poloidal 64-pin probe array alternately measuring potential and density fluctuations. The background flow shear is deduced from radial profiles of the plasma potential as measured with a moveable emissive probe. Spectral contributions to turbulent transport are correlated with the shearing rate and compared to theoretical predictions.