Profiles and fluctuations in edge and SOL turbulence

The time and space averaged profiles of temperature, particle density, and momentum are in the scrape off layer determined by the intermittent transport generated at the edge shear layer. The distinction between profiles and fluctuations becomes arbitrary for situations where the transport is highly intermittent and shows long range correlations. Without this distinction the full range in parameter variability has to be taken into account for simulations, posing extreme demands on the used models. Numerical investigations and experimental results show how the interplay between radially propagating structures and parallel transport sets up the observed profiles and how intermittency influences edge conditions. The filamentary blob structures also transport and generate currents in the SOL, which can be investigated by means of local magnetic diagnostics. Finally, the ratio of ion to electron temperature in the SOL is an important measure for the influence of finite larmor radius effects on the propagation properties of blobs. Numerical investigations indicate that these effects can lead to an increased self confinement and radial reach of these structures.
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim