Increased electron temperature turbulence and pedestal transport in ELM suppressed QH-Mode and RMP DIII-D plasmas

POSTER

Abstract

New observations in DIII-D reveal significant levels of $T_e$ turbulence near the top of the pedestal during ELM-free H-mode operation. These large, increased levels of $T_e$ turbulence are observed in two different scenarios, quiescent H-mode (QH-mode) and resonant magnetic perturbations (RMP), where ELMs have been eliminated. These new results are significant because: 1)the $T_e$ turbulence increase, combined with $~{n}$, provide two distinct states for new and unique tests of nonlinear gyrokinetic simulation predictions; 2)these data provide new insights into the transport mechanisms just inboard of the pedestal top, a region where gyrokinetic simulations are challenging. In ELMing H-modes, the inter-ELM $T_e$ turbulence is close to the noise level and can increase to as much as $1.8\%$ with RMP ELM suppression and to $1.2\%$ in QH-mode. During QH-mode, the $T_e$ turbulence increases with lower collisionality and a similar, but smaller, increase in $T_e$ turbulence is observed in RMP ELM-suppressed plasmas. This is consistent with the growth of Trapped Electron Mode turbulence where destabilization occurs preferentially at lower collisionality. The physics relevance of these new measurements will be discussed in the context of linear stability (TGLF) and power balance analyses

Authors

  • C. Sung

    UCLA

  • T. Rhodes

    University of California, Los Angeles, UCLA

  • W.A. Peebles

    UCLA

  • T. Osborne

    GA, General Atomics

  • G.M. Staebler

    General Atomics, GA

  • S.P. Smith

    General Atomics, GA

  • G. Wang

    GA