First Evidence of Local E×B Drift in the Divertor Influencing the Structure and Stability of Confined Plasma near the Edge of Fusion Devices

H. Q. Wang, H. Y. Guo, G. S. Xu, A. W. Leonard, X. Q. Wu, M. Groth, A. E. Jaervinen, J. G. Watkins, T. H. Osborne, D. M. Thomas, D. Eldon, P. C. Stangeby, F. Turco, J. C. Xu, L. Wang, Y. F. Wang, and J. B. Liu
Phys. Rev. Lett. 124, 195002 – Published 13 May 2020

Abstract

The structure of the edge plasma in a magnetic confinement system has a strong impact on the overall plasma performance. We uncover for the first time a magnetic-field-direction dependent density shelf, i.e., local flattening of the density radial profile near the magnetic separatrix, in high confinement plasmas with low edge collisionality in the DIII-D tokamak. The density shelf is correlated with a doubly peaked density profile near the divertor target plate, which tends to occur for operation with the ion B×B drift direction away from the X-point, as currently employed for DIII-D advanced tokamak scenarios. This double-peaked divertor plasma profile is connected via the E×B drifts, arising from a strong radial electric field induced by the radial electron temperature gradient near the divertor target. The drifts lead to the reversal of the poloidal flow above the divertor target, resulting in the formation of the density shelf. The edge density shelf can be further enhanced at higher heating power, preventing large, periodic bursts of the plasma, i.e., edge-localized modes, in the edge region, consistent with ideal magnetohydrodynamics calculations.

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  • Received 4 October 2019
  • Accepted 17 April 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.195002

© 2020 American Physical Society

Physics Subject Headings (PhySH)

Plasma Physics

Authors & Affiliations

H. Q. Wang1,*, H. Y. Guo1, G. S. Xu2, A. W. Leonard1, X. Q. Wu2, M. Groth3, A. E. Jaervinen4, J. G. Watkins5, T. H. Osborne1, D. M. Thomas1, D. Eldon1, P. C. Stangeby6, F. Turco7, J. C. Xu2,†, L. Wang2, Y. F. Wang2, and J. B. Liu2

  • 1General Atomics, Post Office Box 85608, San Diego, California 92186-5608, USA
  • 2Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
  • 3Department of Applied Physics, Aalto University, FI-00076, Aalto, Finland
  • 4Lawrence Livermore National Laboratory, Livermore, California 94550, USA
  • 5Sandia National Laboratories, Post Office Box 969, Livermore, California 94551, USA
  • 6University of Toronto Institute for Aerospace Studies, 4925 Dufferin St., Toronto M3H 5T6, Canada
  • 7Columbia University, 500 West 120th St., New York, New York 10027, USA

  • *Corresponding author. wanghuiqian@fusion.gat.com
  • Present address: School of Mechanical Engineering, Anhui University of Science and Technology, Huainan 232001, China.

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Vol. 124, Iss. 19 — 15 May 2020

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