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Title: A flux-matched gyrokinetic analysis of DIII-D L-mode turbulence

Previous nonlinear gyrokinetic simulations of specific DIII-D L-mode cases have been found to significantly underpredict the ion heat transport and associated density and temperature fluctuation levels by up to almost one of order of magnitude in the outer-core domain, i.e., roughly in the last third of the minor radius. Since then, this so-called shortfall issue has been subject to various speculations on possible reasons and furthermore motivation for a number of dedicated comparisons for L-mode plasmas in comparable machines. However, only a rather limited number of simulations and gyrokinetic codes has been applied to the original scenario, thus calling for further dedicated investigations in order to broaden the scientific basis. The present work contributes along these lines by employing another well-established gyrokinetic code in a numerically and physically comprehensive manner. Contrary to the previous studies, only a mild underprediction is observed at the outer radial positions which can furthermore be overcome by varying the ion temperature gradient within the error bars associated with the experimental measurement. The significance and reliability of these simulations are demonstrated by benchmarks, numerical convergence tests, and furthermore by extensive validation studies. The latter involve cross-phase and cross-power spectra analyses of various fluctuating quantities and confirmmore » a high degree of realism. The code discrepancies come as a surprise since the involved software packages had been benchmarked repeatedly and very successfully in the past. Further collaborative effort in identifying the underlying difference is hence required.« less
Authors:
;  [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [5]
  1. Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany)
  2. Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
  3. (United States)
  4. Center for Energy Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093 (United States)
  5. Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States)
Publication Date:
OSTI Identifier:
22403342
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 12; Other Information: (c) 2014 EURATOM; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPARATIVE EVALUATIONS; DOUBLET-3 DEVICE; L-MODE PLASMA CONFINEMENT; PLASMA; SIMULATION; TURBULENCE