Search For Zonal Flows In The Edge Turbulence Of Alcator C-Mod
Authors: S.J. Zweben, J.L. Terry, M. Agostini, R. Hager, J.W. Hughes, J.R. Myra, D.C. Pace and the Alcator C-Mod Group
Abstract: The time-dependent radial and poloidal velocity of edge turbulence is evaluated
using a 2-D time-delayed cross-correlation analysis of fast camera data from the gas puff
imaging (GPI) diagnostic viewing the outer midplane region in Alcator C-Mod. The local
poloidal velocity fluctuations are averaged over the poloidal viewing region of the GPI
diagnostic and radially resolved over +2 cm around the separatrix. The resulting poloidal
velocity usually has a broadband frequency spectrum in the range ~1-20 kHz, and a radial
correlation which increases at lower line-averaged density. In some cases with ICRH
heating there was also a coherent poloidal velocity oscillation at 6-7 kHz which was highly
correlated with a poloidal magnetic field oscillation at the same frequency. Some of these
results are similar to the GAMs and/or zonal flows described in previous experiments and
theory.
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Submitted to: Plasma Physics and Controlled Fusion (September 2011)
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Download PPPL-4691 (pdf 5.98 MB 51 pp)
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