Variations in Edge and SOL Turbulence in NSTX
Authors: S.J. Zweben, W.M. Davis, S.M. Kaye, J.R. Myra, R.E. Bell, B.P LeBlanc, R.J. Maqueda, T. Munsat, S.A. Sabbagh, Y. Sechrest, D.P. Stotler, and the NSTX Team
Abstract: This paper describes the range of variations in edge and SOL turbulence observed using a gas puff imaging (GPI) diagnostic in NSTX discharges. The database consists of 140 shots including Ohmic, L-mode, and H-mode plasmas measured during steady-state conditions (e.g. without ELMs). Turbulence quantities were evaluated using both cross correlation analysis and blob tracking. Relative fluctuation levels varied from ~15-100%, correlation times were ~15–40 μsec, correlation lengths were Lpol~ Lrad~5–10 cm, and turbulence velocities were Vpol~2±1 km/sec and Vrad~0.5±0.5 km/sec outward. These variations were evaluated as a function of both the global and local edge plasma parameters, and compared with simplified theoretical models.
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Submitted to: Nuclear Fusion
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