Controlling fluctuations in an ITB and comparison with gyrokinetic simulations

POSTER

Abstract

We have modulated on-axis ICRF minority heating to trigger fluctuations and core electron transport in Alcator C-Mod Internal Transport Barriers (ITB's). Temperature swings of 50\% produced strong bursts of density fluctuations, measured by phase contrast imaging (PCI), while edge fluctuations from reflectometry, Mirnov coils, and gas puff imaging (GPI) simultaneously diminished. The PCI fluctuations are in phase with sawteeth, further evidence that they originate within the ITB foot. Linear gyrokinetic analysis with GS2 shows TEMs are driven unstable in the ITB by the on-axis heating, as in Refs. [1,2]. Nonlinear gyrokinetic simulations of turbulence in the ITB are compared with fluctuation data using a synthetic diagnostic [1]. Strong ITB's were produced with high quality ion and electron profile data. \\[4pt] [1] D. R. Ernst et al., 20th IAEA Fusion Energy Conference (2006), Chengdu, China, paper IAEA-CN-149/TH/1-3. \newline [2] D. R. Ernst et al., Phys. Plasmas 11 (2004) 2637.

Authors

  • Darin Ernst

    MIT PSFC

  • C.L. Fiore

    MIT-PSFC, MIT Plasma Science and Fusion Center

  • A. Dominguez

  • Y. Podpaly

  • M. Reinke

    MIT Plasma Science \& Fusion Center, Cambridge, MA~02139, MIT, PSFC, MIT PSFC, Plasma Science Fusion Center, MIT

  • J.L. Terry

    MIT PSFC, MIT-PSFC

  • N. Tsujii

    MIT Plasma Science and Fusion Center, MIT PSFC

  • I.O. Bespamyatnov

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

  • M. Churchill

    PSFC, MIT

  • Martin Greenwald

    MIT-PSFC, MIT PSFC, MIT

  • Amanda Hubbard

    PSFC, Massachusetts Institute of Technology

  • J.W. Hughes

    MIT PSFC, PSFC

  • Jungpyo Lee

    MIT-PSFC

  • Y. Ma

    MIT PSFC

  • S. Wolfe

    MIT-PSFC, MIT PSFC, PSFC

  • S.J. Wukitch

    MIT PSFC, MIT Plasma Science and Fusion Center, Massachusetts Institute of Technology, PSFC, MIT-PSFC