L-H Transition Dynamics in ITER-Similar Plasmas with Applied n=3 Resonant Magnetic Perturbations

POSTER

Abstract

In ITER-similar plasmas in DIII-D (<ne>=1.5-5x1019m-3, Bt=1.9-2T, Ip=1.5MA, q95~3.6), the L-H threshold power PLH with n=3 Resonant Magnetic Perturbations (RMP) is found to increase with decreasing collisionality [PLH~(nu*)-0.3]. This is a concern for H-mode access in primarily ECH-heated ITER plasmas since RMP may be applied before the L-H transition to safely suppress the first ELM. Non-axisymmetric modifications of the L-mode shear layer with RMP include a substantial local reduction of the Er well and ExB shear (including Er reversal at high RMP field), and spatially modulated low-wavenumber turbulence amplitude, increasing substantially on field lines mapped to high RMP field. Two-fluid M3D-C1 modeling [1,2] shows that the normalized gradients a/L_n, a/L_Te are toroidally modulated and periodically increased on the outboard midplane with RMP. The increase in PLH is atttributed to the combined effects of reduced (and non-axisymmetric) ExB flow / flow shear, and locally enhanced instability drive (via increased kinetic gradients). [1] N.M. Ferraro,Phys. Plasmas 19 056105 (2012); [2] R.S. Wilcox et al. Phys. Plasmas 25 056108 (2018).

Presenters

  • Lothar W Schmitz

    University of California, Los Angeles, Univ of California - Los Angeles, TAE Technologies, University of California Los Angeles, TAE Technologies, University of California Los Angeles, Univ of California - Los Angeles

Authors

  • Lothar W Schmitz

    University of California, Los Angeles, Univ of California - Los Angeles, TAE Technologies, University of California Los Angeles, TAE Technologies, University of California Los Angeles, Univ of California - Los Angeles

  • T.L. Rhodes

    University of California Los Angeles

  • Lei Zeng

    Univ of California - Los Angeles, University of California Los Angeles

  • M. Kriete

    University of Wisconsin, Madison

  • Zheng Yan

    Univ of Wisconsin, Madison, University of Wisconsin–Madison, University of Wisconsin - Madison, University of Wisconsin, Madison

  • George R Mckee

    Univ of Wisconsin, Madison, Univ of Wisconsin, Madison, Univ of Wisconsin, Madison, University of Wisconsin–Madison, University of Wisconsin-Madison, University of Wisconsin - Madison, University of Wisconsin, Madison, Univ. of Wisconsin, Madison

  • Robert Wilcox

    Oak Ridge National Laboratory, ORNL, Oak Ridge National Laboratory, USA

  • C. Alberto Paz-Soldan

    General Atomics - San Diego, General Atomics, GA

  • P. Gohil

    General Atomics

  • C Craig Petty

    General Atomics, General Atomics - San Diego, GA

  • M. Marinoni

    Massachusetts Institute of Technology - PSFC, Massachusetts Inst of Tech-MIT, MIT-PSFC, MIT