High beta stability research on KSTAR at high non-inductive fraction

ORAL

Abstract

KSTAR plasmas have exceeded the ideal n = 1 no-wall MHD stability limit and reached βN > 4. Analysis of advanced operation regimes using TRANSP indicate that the non-inductive current fraction has reached 75 percent. Regions of weak safety factor q shear can form in different parts of the plasma dependent upon the broadness of the bootstrap current profile. Kinetic equilibrium reconstructions with MSE data to constrain the local magnetic field pitch angle are used as input to evaluate ideal and resistive stability using DCON. At present, high βN operation is limited by tearing instabilities rather than resistive wall modes (RWM) that are computed to be stabilized by kinetic MHD effects. TRANSP code predictive capability is used to examine the effects of the second (off-axis) NBI system installed for the 2018 run determining plasma parameters important for stability. Values of the global energy confinement quality (H98y2) and the Greenwald density fraction are set to match past performance for reliable extrapolation. Predictive analyses are used to design experiments yielding solutions with βN~4.5 and 100% non-inductive current drive. Active RWM feedback with both DC and AC field compensation has been implemented for mode control in 2018.

*Supported by US DOE grant DE-SC0016614.

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Presenters

  • Steven Anthony Sabbagh

    • Columbia University
    • Columbia U.
    • Columbia Univ

Authors

  • Steven Anthony Sabbagh

    • Columbia University
    • Columbia U.
    • Columbia Univ

  • Young-Seok Park

    • Columbia U.
    • Columbia Univ
    • Columbia University

  • John W Berkery

    • Columbia U.

  • Jae-Heon Ahn

    • Columbia U.
    • Columbia Univ
    • Columbia University

  • Yanzheng Jiang

    • Columbia U.
    • Columbia Univ
    • Columbia University

  • Juan D Riquezes

    • Columbia U.
    • Columbia Univ
    • Columbia U
    • Columbia University

  • Jun-Gyo Bak

    • National Fusion Research Institute

  • Sang-Hee Hahn

    • National Fusion Research Institute
    • Natl Fusion Res Inst
    • NFRI

  • Hyunsun Hahn

    • National Fusion Research Institute
    • Natl Fusion Res Inst

  • Young-Mu Jeon

    • National Fusion Research Institute

  • Jayhyun Kim

    • National Fusion Research Institute

  • Hyun-Seok Seok Kim

    • National Fusion Research Institute

  • Jin-Seok Ko

    • National Fusion Research Institute
    • Natl Fusion Res Inst, University of Science and Technology in Korea
    • NFRI
    • National Fusion Research Institute, National Fusion Research Institute

  • Won Ha Ko

    • Natl Fusion Res Inst
    • National Fusion Research Institute

  • Jong-Hua Lee

    • National Fusion Research Institute
    • Natl Fusion Res Inst

  • Byung-Ho Park

    • National Fusion Research Institute

  • Laurent Terzolo

    • National Fusion Research Institute
    • NFRI

  • Si-Woo Yoon

    • Natl Fusion Res Inst
    • National Fusion Research Institute

  • Alan Herbert Glasser

    • Fusion Theory & Computation, Inc.
    • Fusion Theory and Computation, Inc.

  • Zhirui Wang

    • PPPL
    • Princeton Plasma Phys Lab