Hannover 2010 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 13: Magnetic Confinement
P 13.1: Fachvortrag
Mittwoch, 10. März 2010, 14:30–14:55, B 305
Experimental investigations of the parallel dynamics of turbulent fluctuations in the scrape-off layer of Alcator C-Mod — •Olaf Grulke1, James L. Terry2, and Brian LaBombard2 — 1MPI for Plasma Physics, EURATOM Association, and EMA University, Greifswald — 2PSFC, MIT, Cambridge, USA
It is generally observed that spatiotemporal turbulent structures in the scrape-off layer (SOL) of tokamaks are predominantly driven in the bad curvature region around the outboard midplane. However, those structures form filaments, which are fairly well aligned with and spread along the magnetic and are thus observed over a wide poloidal region. The parallel dynamics is of special interest since it determines important reactor quantities, like first wall recycling and divertor heat load. This paper presents experimental investigations of the parallel structure and dynamics of turbulent fluctuations in the SOL of Alcator C-Mod. The experimental approach is to observe the evolution of fluctuations using a set of diagnostics, which measure simultaneously along a magnetic flux tube. The fluctuations at the outboard midplane are detected using an 9x10 array of Dalpha diode views, spanning 4cm in vertical and horizontal direction. For particular magnetic field configurations this view is magnetically connected to either a scanning probe close to the lower X-point or past the X-point to divertor probes. A comparison of the statistical properties of the fluctuations in the three different regions and their dependence on the plasma density are presented. Based on correlation investigations the timescales of the parallel propagation are extracted.