Multi-scale Simulations of DIII-D near-edge L-mode plasmas

ORAL

Abstract

In order to self-consistently describe the L-H transition we have to be able to quantitatively characterize near-edge L-mode plasmas ($\rho$=0.8). Instructed by a linear analysis, we perform nonlinear gyrokinetic simulations of a DIII-D L-mode discharge. Comparison between single-scale and multi-scale simulations reveals that stability of ion temperature gradient (ITG) turbulence affects cross-scale coupling. When ion transport is stabilized by zonal flows, electron temperature gradient (ETG) streamer amplitude is reduced but persists at sub-ion-scales, causing radial electron heat transport to dominate. When ITG modes are unstable, we find that ion heat transport dominates, in agreement with experimental data. Moreover, nonlinear de-stabilization of ion transport occurs at higher critical gradients for multi-scale than for single-scale simulations, showing an enhanced Dimits shift. All simulations are performed with the GENE code (genecode.org).

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Authors

  • T. Neiser

    UCLA

  • Frank Jenko

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

  • T. A. Carter

    UCLA, University of California, Los Angeles

  • Lothar Schmitz

    UCLA, University of California, Los Angeles

  • Daniel Told

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

  • Alejandro Banon Navarro

    University of California, Los Angeles, UCLA

  • G.R. McKee

    U.W. Madison, U. Wisconsin-Madison, U WISCONSIN, UW Madison, University of Wisconsin-Madison, U.W.-Madison, U Wisc. M, U. Wisc.-Madison, U Wisc M, U Wisc-Madison, UW-MADISON, UWisc

  • Z. Yan

    U.W. Madison, U. Wisconsin-Madison, U WISCONSIN, U. Wisc.-Madison, U Wisc M, U Wisc-Madison