A flux-matched gyrokinetic analysis of DIII-D L-mode turbulence
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Author(s)
Görler, T.
Told, D.
Jenko, F.
Holland, C.
Rhodes, T. L.
White, Anne E.
Date Issued
December 2014
Journal
Physics of Plasmas
Publisher
American Institute of Physics (AIP)
Citation
Görler, T., A. E. White, D. Told, F. Jenko, C. Holland, and T. L. Rhodes. “A Flux-Matched Gyrokinetic Analysis of DIII-D L-Mode Turbulence.” Phys. Plasmas 21, no. 12 (December 2014): 122307. © 2014 EURATOM
Version
Final published version
Abstract
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 confirm 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.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
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DOI of Published Version
https://doi.org/10.1063/1.4904301
