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Title: Measurements of non-axisymmetric effects in the DIII-D divertor

Non-stationary toroidal asymmetries are observed in the DIII-D divertor heat flux and scrape-off layer (SOL) currents. Using the present DIII-D diagnostics asymmetries are seen much less frequently in single-null H-modes (<5%) than in double-null H-modes (>50%). Divertor heat flux asymmetries are characterized by toroidal variations in the radial profile (i.e., multiple or bifurcated peaks at some toroidal locations and single peaks at others) while SOL currents sometimes have a strongly bipolar toroidal structure. SOL current asymmetries are particularly large during Edge Localized Modes (ELMs). In some cases heat flux variations of as much as a factor of two are seen. The measurements reported here indicate that these asymmetries are best described by a model in which non-axisymmetric radial magnetic perturbations create magnetic islands in the plasma boundary and scrape-off layer which then cause toroidal variation in the divertor heat flux and the scrape-off layer currents.
Authors:
; ; ;  [1] ; ; ;  [2]
  1. General Atomics, San Diego, CA (United States)
  2. Lawrence Livermore National Lab., CA (United States)
Publication Date:
OSTI Identifier:
10182064
Report Number(s):
GA-A--21707; CONF-940580--17
ON: DE94018346; BR: 35AT10020/35KC07000
DOE Contract Number:
AC03-89ER51114; AC05-84OR21400; W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: 11. international conference on plasma surface interactions in controlled fusion devices,Mito (Japan),23-27 May 1994; Other Information: PBD: Jul 1994
Research Org:
General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab., CA (United States); Oak Ridge National Lab., TN (United States)
Sponsoring Org:
USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DIVERTORS; HEAT FLUX; PLASMA SCRAPE-OFF LAYER; CURRENTS; PLASMA DIAGNOSTICS; DOUBLET-3 DEVICE; EDGE LOCALIZED MODES; AXIAL SYMMETRY; H-MODE PLASMA CONFINEMENT 700420; 700320; PLASMA-FACING COMPONENTS; PLASMA DIAGNOSTIC TECHNIQUES AND INSTRUMENTATION