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Abstract:
Formation of nonlinear structures in drift-Alfvén turbulence is investigated in the often complex edge geometries of stellarator and
tokamak configurations, by analysis of drift wave turbulence simulations using a model in which three-dimensional magnetic
geometries are approximated. The structures of parallel mode extension, radially sheared zonal flows and perpendicular mode
spectra are highlighted in particular for three-dimensional stellarator magnetic fields and shaped tokamaks. Specific
characteristics of advanced stellarators in comparison to (lower aspect ratio) circular tokamaks are a less pronounced ballooning
structure of the modes, a strong influence of local magnetic shear on amplitude structure and average, and stronger level of zonal
flows due to lower geodesic curvature.
