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Title: Effect of chaos on plasma filament dynamics and turbulence in the scrape-off layer

Naturally occurring error fields as well as resonant magnetic perturbations applied for stability control are known to cause magnetic field-line chaos in the scrape-off layer (SOL) region of tokamaks. Here, 2D simulations with the BOUT++ simulation framework are used to investigate the effect of the field-line chaos on the SOL and in particular on its width and peak particle flux. The chaos enters the SOL dynamics only through the connection length, which is evaluated using a Poincaré map. The variation of experimentally relevant quantities, such as the SOL gradient length scale and the intermittency of the particle flux in the SOL, is described as a function of the strength of the magnetic perturbation. It is found that the effect of the chaos is to broaden the profile of the sheath-loss coefficient, which is proportional to the inverse connection length. That is, the SOL transport in a chaotic field is equivalent to that in a model where the sheath-loss coefficient is replaced by its average over the unperturbed flux surfaces. The model does not include the effects of chaotic features other than the parallel connection length.
Authors:
; ;  [1] ;  [2]
  1. Institute for Fusion Studies (IFS), Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States)
  2. Institute for Computational Engineering and Sciences (ICES), Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, Texas 78712 (United States)
Publication Date:
OSTI Identifier:
22299816
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CHAOS THEORY; CONTROL; DISTURBANCES; MAGNETIC FIELDS; MAGNETIC SURFACES; PERTURBATION THEORY; PLASMA FILAMENT; PLASMA SCRAPE-OFF LAYER; TOKAMAK DEVICES