First Evidence of the Role of Zonal Flows for the LH Transition at Marginal Input Power in the EAST Tokamak

G. S. Xu, B. N. Wan, H. Q. Wang, H. Y. Guo, H. L. Zhao, A. D. Liu, V. Naulin, P. H. Diamond, G. R. Tynan, M. Xu, R. Chen, M. Jiang, P. Liu, N. Yan, W. Zhang, L. Wang, S. C. Liu, and S. Y. Ding
Phys. Rev. Lett. 107, 125001 – Published 14 September 2011

Abstract

A quasiperiodic Er oscillation at a frequency of <4kHz, much lower than the geodesic-acoustic-mode frequency, with a modulation in edge turbulence preceding and following the low-to-high (LH) confinement mode transition, has been observed for the first time in the EAST tokamak, using two toroidally separated reciprocating probes. Just prior to the LH transition, the Er oscillation often evolves into intermittent negative Er spikes. The low-frequency Er oscillation, as well as the Er spikes, is strongly correlated with the turbulence-driven Reynolds stress, thus providing first evidence of the role of the zonal flows in the LH transition at marginal input power. These new findings not only shed light on the underlying physics mechanism for the LH transition, but also have significant implications for ITER operations close to the LH transition threshold power.

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  • Received 19 May 2011

DOI:https://doi.org/10.1103/PhysRevLett.107.125001

© 2011 American Physical Society

Authors & Affiliations

G. S. Xu1, B. N. Wan1, H. Q. Wang1, H. Y. Guo1,2, H. L. Zhao3, A. D. Liu3, V. Naulin4, P. H. Diamond5, G. R. Tynan5, M. Xu5, R. Chen1, M. Jiang1, P. Liu1, N. Yan1, W. Zhang1, L. Wang1, S. C. Liu1, and S. Y. Ding1

  • 1Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
  • 2Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688, USA
  • 3Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
  • 4Association Euratom-Risø DTU, DK-4000 Roskilde, Denmark
  • 5University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA

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Vol. 107, Iss. 12 — 16 September 2011

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