Intermittency in the Scrape-off Layer of the National Spherical Torus Experiment During H-mode Confinement

R.J. Maqueda, D.P. Stotler, S.J. Zweben, and the NSTX Team

关键词: BEAM INJECTION;    CONFINEMENT;    EMISSION;    FLUCTUATIONS;    INHIBITION;    LAYERS;    LEVELS;    POWER;    SOLS;    TURBULENCE;    USES Edge Plasma;    Scrape-off Layer (SOL;    Transport Phenomena;    Tokamaks;    NSTX;   

DOI  :  10.2172/1001663
RP-ID  :  PPPL-4574
PID  :  OSTI ID: 1001663
Others  :  TRN: US1100795

学科分类：原子、分子光学和等离子物理

美国|英语

来源: SciTech Connect

【 摘 要 】

A gas puff imaging diagnostic is used in the National Spherical Tokamak Experiment [M. Ono, et al., Nucl. Fusion 40, 557 (2000)] to study the edge turbulence and intermittency present during H-mode discharges. In the case of low power Ohmic H-modes the suppression of turbulence/blobs is maintained through the duration of the (short lived) H-modes. Similar quiescent edges are seen during the early stages of H-modes created with the use of neutral beam injection. Nevertheless, as time progresses following the L-H transition, turbulence and blobs reappear although at a lower level than that typically seen during L-mode confinement. It is also seen that the time-averaged SOL emission profile broadens, as the power loss across the separatrix increases. These broad profiles are characterized by a large level of fluctuations and intermittent events.