High Speed Imaging of Edge Turbulence in NSTX

Zweben, S. J. ; Maqueda, R. ; Stotler, D. P. ; Keesee, A. ; Boedo, J. ; Bush, C. ; Kaye, S. ; LeBlanc, B. ; Lowrance, J. ; Mastrocola, V. ; Maingi, R. ; Nishino, N. ; Renda, G. ; Swain, D. ; Wilgen, J. ; National Spherical Torus Experiment (Project)

Nuclear Fusion 44 (Jan 2004) 134-153

关键词: 70 Plasma Physics And Fusion Technology;    Spherical Tokamak;    Edge Plasma;    Velocity Edge Plasma;    Turbulence;   

DOI  :  10.2172/812921
RP-ID  :  PPPL-3795
RP-ID  :  AC02-76CH03073
RP-ID  :  812921

美国|英语

来源: UNT Digital Library

【 摘 要 】

The two-dimensional radial versus poloidal structure and motion of edge turbulence in NSTX (National Spherical Torus Experiment) were measured by using high-speed imaging of the visible light emission from a localized neutral gas puff. Edge turbulence images are shown and analyzed for Ohmic, L-mode (low-confinement mode) and H-mode (high-confinement mode) plasma conditions. Typical edge turbulence poloidal correlation lengths as measured using this technique are = 4 {+-} 1 cm and autocorrelation times are 40 {+-} 20 {micro}sec in all three regimes. The relative fluctuation level is typically smaller in H-mode than in L-mode, and transitions from H- to L-mode and can occur remarkably quickly (=30 {micro}sec). The two-dimensional images often show localized regions of strong light emission which move both poloidally and radially through the observed region at a typical speed of =10{sup 5} cm/sec, and sometimes show spatially coherent modes.