First evidence of the role of zonal flows for the L-H 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, Volker Naulin, P. H. Diamond, G. R. Tynan, M. Xu, R. Chen, M. Jiang, P. Liu, N. Yan, W. Zhang, L. Wang, S. C. Liu, S. Y. Ding

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    A quasiperiodic Er oscillation at a frequency of <4 kHz, much lower than the geodesic-acoustic-mode frequency, with a modulation in edge turbulence preceding and following the low-to-high (L-H) confinement mode transition, has been observed for the first time in the EAST tokamak, using two toroidally separated reciprocating probes. Just prior to the L-H 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 L-H transition at marginal input power. These new findings not only shed light on the underlying physics mechanism for the L-H transition, but also have significant implications for ITER operations close to the L-H transition threshold power.
    Original languageEnglish
    JournalPhysical Review Letters
    Volume107
    Issue number12
    Pages (from-to)125001
    ISSN0031-9007
    DOIs
    Publication statusPublished - 2011

    Keywords

    • Fusion energy

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