Download or read book Observations of the Turbulence in the Scrape-off-layers of Alcator C-Mod and NSTX and Comparisons with Simualtion [sic] written by James L. Terry and published by . This book was released on 2002 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: The intermittent turbulent transport in the scrape-off-layer of Alcator C-Mod and NSTX is studied experimentally by imaging with a very high density of spatial measurements. The 2-D structure and dynamics of emission from a localized gas puff are observed, and intermittent features (also sometimes called "filaments" or "blobs") are typically seen. The characteristics of the spatial structure of the turbulence and their relationship to the time-averaged SOL profiles are discussed. The experimental observations are compared with 3-D non-linear numerical simulations of edge turbulence. Radial profiles of the poloidal wavenumber spectra and the poloidal scale length from the simulations are in reasonable agreement with those obtained from the experimental images, once the response of the optical system is accounted for. The resistive ballooning mode is the dominant linear instability in the simulations. The ballooning character of the turbulence is also consistent with fluctuation measurements made at the inboard and outboard midplane, where normalized fluctuation levels are found to be about ten times smaller on the inboard side. For discharges near the density limit, turbulent structures are seen on closed flux surfaces. Keywords: turbulence; edge plasma; fluctuations; transport phenomena; resistive instabilities.