Comparison of Scrape-off Layer Turbulence in Alcator C-Mod with Three Dimensional Gyrofluid Computations [report]

S. J. Zweben, B. D. Scott, J. L. Terry, B. LaBombard, J. W. Hughes, D. P. Stotler
2009 unpublished
This paper describes quantitative comparisons between turbulence measured in the scrape-off layer ͑SOL͒ of Alcator C-Mod ͓S. Scott, A. Bader, M. Bakhtiari et al., Nucl. Fusion 47, S598 ͑2007͔͒ 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
more » ... yroradius 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 D a fluctuation levels were higher in the experiment by more than a factor of 2. Possible causes for these disagreements are discussed.
doi:10.2172/963546 fatcat:6aw4rnvzorchnlbaqxmbnmxkm4