High Speed Imaging of Edge Turbulence in NSTX

Technical Report · Fri Feb 28 23:00:00 EST 2003

DOI:https://doi.org/10.2172/812921· OSTI ID:812921

Zweben, S J ^[1]; 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

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1. Princeton Plasma Physics Laboratory

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.

• Research Organization: Princeton Plasma Physics Lab., NJ (US)
• Sponsoring Organization: USDOE Office of Science (SC) (US)
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 812921
• Report Number(s): PPPL-3795
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
EDGE PLASMA
FLUCTUATIONS
PLASMA
SPHERICAL TOKAMAK
TURBULENCE
VELOCITY