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Title: Gyrokinetic studies of trapped electron mode turbulence in the Helically Symmetric eXperiment stellarator

Gyrokinetic simulations of plasma microturbulence in the Helically Symmetric eXperiment are presented. Using plasma profiles relevant to experimental operation, four dominant drift wave regimes are observed in the ion wavenumber range, which are identified as different flavors of density-gradient-driven trapped electron modes. For the most part, the heat transport exhibits properties associated with turbulence driven by these types of modes. Additionally, long-wavelength, radially localized, nonlinearly excited coherent structures near the resonant central flux surface, not predicted by linear simulations, can further enhance flux levels. Integrated heat fluxes are compatible with experimental observations in the corresponding density gradient range. Despite low shearing rates, zonal flows are observed to regulate turbulence but can be overwhelmed at higher density gradients by the long-wavelength coherent structures.
Authors:
 [1] ;  [2] ; ;  [3] ;  [4] ;  [5] ;  [4] ;  [3] ;  [2] ; ; ;  [1]
  1. HSX Plasma Lab, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
  2. (United States)
  3. Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
  4. Max Planck Institute for Plasma Physics, Wendelsteinstr. 1, 17491 Greifswald (Germany)
  5. (Germany)
Publication Date:
OSTI Identifier:
22490004
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 7; Other Information: (c) 2015 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; HEAT FLUX; HEAT TRANSFER; HSX STELLARATOR; MAGNETIC SURFACES; NONLINEAR PROBLEMS; PLASMA RADIAL PROFILES; SHEAR; SIMULATION; TRAPPED ELECTRONS; TURBULENCE; WAVE PROPAGATION; WAVELENGTHS