Regimes of weak ITG/TEM for transport barriers without velocity shear

POSTER

Abstract

We show there exists a regime where coupled ITG/TEM modes are hugely weakened enabling Transport Barriers (TB). The passage to this regime has arisen in TBs in multiple experimental contexts: ITB in DIII-D, JET, W7X and EAST, H-mode pedestals on DIII-D and JET, and likely very many others. We examine representative cases of these. A distinguishing and crucial feature of the analysis is that the regime is understood in terms of general concepts of non-equilibrium thermodynamics. A constraint founded in momentum conservation limits fluctuations that try to maximize entropy production, and so enables steep gradients in TBs. A very large number of linear and non-linear gyrokinetic simulations with GENE are used, in controlled scans, and for experimental cases, with novel analytic tools to understand this regime and its underlying cause. The proposed National Compact Stellarator device gives especially favorable results.

Authors

  • M. Kotschenreuther

    University of Texas at Austin

  • X. Liu

    University of Texas at Austin

  • David Hatch

    Institute for Fusion Studies, University of Texas at Austin, University of Texas at Austin, The University of Texas at Austin, Texas

  • S. Mahajan

    University of Texas at Austin, University of Texas at Austin: Institute of Fusion Studies

  • M.J. Pueschel

    University of Texas at Austin, Institute for Fusion Studies, University of Texas at Austin, University of Wisconsin - Madison, Dutch Institute for Fundamental Energy Research

  • Michael Halfmoon

    University of Texas at Austin, The University of Texas at Austin

  • Michael Zarnstorff

    Princeton Plasma Physics Laboratory, PPPL

  • A.M. Garofalo

    General Atomic, General Atomics, General Atomics - San Diego, (GA)

  • J. McClenaghan

    General Atomics, General Atomic, General Atomics - San Diego, (GA)

  • Ian McKinney

    University of Wisconsin, University of Wisconsin - Madison

  • Jinping Qian

    ASIPP, (ASIPP), Institute of Plasma Physics, Chinese Academy of Sciences

  • S. Ding

    General Atomic, (ORAU)

  • C. Giroud

    Culham Centre fo Fusion Energy

  • J. C. Hillesheim

    Culham Centre fo Fusion Energy

  • C. F. Maggi

    Culham Centre fo Fusion Energy

  • S. Saarelma

    Culham Centre fo Fusion Energy

  • Xi Chen

    General Atomic, General Atomics