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P: Plasmaphysik
P 4: Diagnostik 1; Niedertemperaturplasmen / Plasmatechnologie 2; Magnetischer Einschluß 2
P 4.29: Poster
Monday, March 27, 2006, 17:00–19:00, Flure
Scaling of the radial velocity of turbulent structures in tokamak SOL — •Olaf Grulke1, James L. Terry2, Brian LaBombard2, and Stewart J. Zweben3 — 1MPI for Plasma Physics, EURATOM Association, Greifswald, Germany — 2Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, USA — 3Princeton Plasma Physics Laboratory, Princeton, USA
A distinct feature of plasma turbulence in the scrape-off layer (SOL) of fusion experiments is the formation of spatiotemporal structures with large fluctuation amplitudes. The dynamics of these structures is not only in poloidal direction, i.e. the direction of the time-averaged plasma drifts, but they propagate radially outwards, thereby contributing significantly to cross-field heat and particle transport. Several models have been proposed to quantify the radial propagation speed in dependence on specific structure properties, like fluctuation amplitude, structure size, connection length to material boundaries etc. In this paper the different proposed scalings are reviewed and compared to measurements in the SOL of the Alcator C-Mod and NSTX tokamak. Experimentally, the structures are diagnosed using turbulence imaging techniques [1]. The images are decomposed in different amplitude and spatial scales. Structure tracking algorithms provide probability distributions of radial and poloidal velocities of the different scales, which are compared to the theoretical predictions.
[1] S.J. Zweben et al., Phys. Plasmas 9(5), 2002