ETG-dominated transport regimes in near-edge DIII-D L-mode plasmas: Validation of multiscale gyrokinetic simulations

ORAL

Abstract

A prerequisite for the development of a self-consistent theoretical description of the L-H transition is the ability to quantitatively characterize near-edge L-mode plasmas. It is shown here for the first time that regimes exist in the L-mode near-edge that appear to be dominated by sub-ion-scale turbulence driven by electron temperature gradient (ETG) modes. These are results of gyrokinetic simulations of a DIII-D L-mode discharge in the near edge region (r/a $=$ 0.8) with the GENE code (www.genecode.org). Instructed by a linear analysis, we performed nonlinear simulations of ITG and ETG turbulence, pointing to a dominance of ETG turbulence regarding the anomalous radial heat flux. Direct comparison with experimental data is encouraging. Respective multi-scale simulations, covering both ion and electron scales are underway and will be presented. Implications for L-H transition modeling will also be discussed.

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Authors

  • Tom Neiser

    UCLA

  • F. Jenko

    Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA, UCLA, Univ of California - Los Angeles, University of California at Los Angeles

  • Lothar Schmitz

    UCLA

  • D. Told

    UCLA, University of California at Los Angeles

  • Alejandro Banon Navarro

    UCLA, University of California Los Angeles, University of California, Los Angeles

  • Troy Carter

    UCLA

  • Z. Yan

    General Atomics, U. Wisc-Madison

  • George McKee

    General Atomics, U. of Wisc., University of Wisconsin-Madison