Kiel 2004 – scientific programme
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P: Plasmaphysik
P 19: Magnetischer Einschluss III
P 19.5: Fachvortrag
Thursday, March 11, 2004, 12:10–12:30, H\"orsaal D
Spatiotemporal dynamics of turbulent SOL fluctuations in ALCATOR C-Mod: Comparison between Ohmic and EDA discharges — •Olaf Grulke1, James L. Terry2, Brian LaBombard2, and Stewart J. Zweben3 — 1MPI for Plasma Physics, EURATOM Association, Greifswald, Germany — 2Massachusetts Institute of Technology, Cambridge, USA — 3Princeton Plasma Physics Laboratory, Princeton, USA
A general feature of turbulent fluctuations in magnetized plasmas is the strong anisotropy with much higher correlation length along the magnetic field lines when compared to the perpendicular direction. We present investigations on the dynamics of turbulent fluctuations in the SOL of the Alcator C-Mod tokamak. In the poloidal plane fluctuations are characterized by two-dimensional imaging of the Dα emission of a localized gas puff with a fast camera (250kHz frame rate) and a radial array of fast optical diodes. These intensity fluctuations are due in part to plasma density fluctuations. Additionally an electric probe is used to measure potential fluctuations on a magnetic flux tube connecting to the emission region of the gas puff. In the poloidal plane the formation and propagation of large-scaled structures is observed, which contribute to cross-field transport by a significant radial propagation. Along the magnetic field the turbulent fluctuations form striations with a typical correlation coefficient of up to 50% at a separation distance of ∼ 3m. The dynamics of structures in Ohmic and EDA discharges are compared.