Hannover 2010 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 15: Invited Talks Mayer, Liang, Wolfrum, Schulz-von der Gathen

P 15.3: Hauptvortrag

Donnerstag, 11. März 2010, 12:00–12:30, B 305

The latest experimental results for the edge transport barrier in tokamaks — •Elisabeth Wolfrum, Bernd Wieland, Philip Schneider, Andreas Burckhart, Bernd Kurzan, Rainer Fischer, Thomas Puetterich, and ASDEX Upgrade Team — Max-Planck-Institut für Plasmaphysik, EURATOM, Boltzmannstr. 2, 85748 Garching, Deutschland

Improvements to edge diagnostics in terms of spatial and temporal resolution allow a more detailed look at the edge transport barrier, which determines not only the performance in the core of an H-mode (high confinement mode) plasma but also the processes in the region outside the last closed flux surface.

The profiles of electron density, electron and ion temperature, toroidal velocity as well as of the radial electric field show a narrow edge transport barrier, approximately the same width as one poloidal gyroradius. While the electron temperature width changes with plasma pressure, the electron density width does not. The radial electric field exhibits a minimum at the position of the maximum of the ratio of pressure gradient and density, which is in accordance with the radial force balance equation, provided that the perpendicular fluid velocity is small.

An investigation of the temporal development of electron density and temperature profiles in between ELMs, reveals different phases, in which various transport mechanisms dominate. It can be shown, that the gradients of density and temperature develop on different time scales, but influence each other.