Comparison of Scrape-off Layer Turbulence in Alcator C-Mod with Three Dimensional Gyrofluid Computations
Authors: S.J. Zweben, B.D. Scott, J.L. Terry, B. LaBombard, J.W. Hughes, and D.P. Stotler
Abstract:
This paper describes quantitative comparisons between turbulence measured in the scrape-off layer
(SOL) of Alcator C-Mod [S. Scott, A. Bader, M. Bakhtiari et al., Nucl. Fusion 47, S598 (2007)] and
three dimensional computations using electromagnetic gyrofluid equations in a two-dimensional
tokamak geometry. These comparisons were made for the outer midplane SOL for a set of inner-wall
limited, near-circular Ohmic plasmas. The B field and plasma density were varied to assess
gyroradius and collisionality scaling. The poloidal and radial correlation lengths in the experiment
and computation agreed to within a factor of 2 and did not vary significantly with either B or density.
The radial and poloidal propagation speeds and the frequency spectra and poloidal k-spectra also
agreed fairly well. However, the autocorrelation times and relative Da fluctuation levels were higher
in the experiment by more than a factor of 2. Possible causes for these disagreements are
discussed. 2009 American Institute of Physics.
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Submitted to: Physics of Plasmas (April 2009)
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Download PPPL-4438 (pdf 289 KB 12 pp)
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