ITER-Relevant Turbulence Broadening of the Divertor Heat Flux Width in DIII-D Quiescent H-Mode Plasmas Featuring Turbulence-Limited Pedestals

ORAL

Abstract

Multi-machine scaling predicts a narrow heat exhaust layer in future high magnetic field tokamaks, producing extreme power densities that require mitigation. In our experiments, the width of the exhaust layer is nearly doubled using actuators to increase turbulent transport in the plasma edge. This is achieved in low collisionality, high confinement Quiescent H-Mode edge pedestals with their gradients limited by turbulence, instead of coherent MHD modes or Edge Localized Modes, consistent with predictions that ITER pedestal turbulent transport will greatly exceed that of present machines. The exhaust heat flux profile width and divertor leg diffusive spreading both double as a high frequency band of turbulent fluctuations propagating in the electron diamagnetic direction doubles in amplitude [1]. The results are quantitatively reproduced in electromagnetic XGC particle-in-cell simulations which show the heat flux carried by electrons emerges to broaden the heat flux profile, directly supported by Langmuir probe measurements and infra-red thermography. The broadening of the total heat flux profile is measured by infra-red thermography. The XGC simulations show pedestal fluctuations characteristic of trapped electron modes (TEMs), consistent with the increased electron heat flux.

[1] D. R. Ernst et al., Phys. Rev. Lett. 132, 235102 (2024). https://doi.org/10.1103/PhysRevLett.132.235102

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Publication: D. R. Ernst et al., Phys. Rev. Lett. 132, 235102 (2024). https://doi.org/10.1103/PhysRevLett.132.235102

Presenters

  • Darin R Ernst

    Massachusetts Institute of Technology MIT, Massachusetts Institute of Technology

Authors

  • Darin R Ernst

    Massachusetts Institute of Technology MIT, Massachusetts Institute of Technology

  • Alessandro Bortolon

    Princeton Plasma Physics Laboratory

  • C. S Chang

    Princeton Plasma Physics Laboratory, Princeton University

  • Seung-Hoe Ku

    Princeton Plasma Physics Laboratory, Princeton University

  • Filippo Scotti

    Lawrence Livermore Natl Lab, Lawrence Livermore National Laboratory

  • Huiqian Wang

    General Atomics

  • Zheng Yan

    University of Wisconsin - Madison, University of Wisconsin Madison

  • Jie Chen

    University of California, Los Angeles

  • Colin Chrystal

    General Atomics - San Diego, General Atomics

  • Fenton Glass

    General Atomics - San Diego

  • Shaun R Haskey

    Princeton Plasma Physics Laboratory

  • Ryan T Hood

    Sandia National Laboratories

  • Filipp O Khabanov

    University of Wisconsin - Madison, Univ Wisconsin,Madison

  • Florian M. M Laggner

    North Carolina State University

  • Charlie Lasnier

    Lawrence Livermore National Laboratory

  • George R McKee

    University of Wisconsin-Madison, University of Wisconsin, Madison

  • Terry L Rhodes

    University of California, Los Angeles

  • Dinh Truong

    Sandia National Laboratory, Livermore, CA, Lawrence Livermore National Laboratory

  • Jon G Watkins

    General Atomics - San Diego, Sandia National Laboratories