Time-resonant tokamak plasma edge instabilities?

A.J. Webster (Corresponding Author), R.O. Dendy, F.A. Calderon, S.C. Chapman, E. Delabie, D. Dodt, R. Felton, T.N. Todd, F. Maviglia, J. Morris, V. Riccardo, B. Alper, S. Brezinsek, P. Coad, Jari Likonen, M. Rubel, JET EFDA Contributors

    Research output: Contribution to journalArticleScientificpeer-review

    9 Citations (Scopus)


    For a two week period during the Joint European Torus 2012 experimental campaign, the same high confinement plasma was repeated 151 times. The dataset was analysed to produce a probability density function (pdf) for the waiting times between edge-localized plasma instabilities (ELMs). The result was entirely unexpected. Instead of a smooth single peaked pdf, a succession of 4-5 sharp maxima and minima uniformly separated by 7-8ms intervals was found. Here we explore the causes of this newly observed phenomenon, and conclude that it is either due to a naturally occurring self-organized plasma phenomenon or an interaction between the plasma and a real-time control system. If the maxima are a result of 'resonant' frequencies at which ELMs can be triggered more easily, then future ELM control techniques can, and probably will, use them. Either way, these results demand a deeper understanding of the ELM process.
    Original languageEnglish
    Number of pages6
    JournalPlasma Physics and Controlled Fusion
    Issue number7
    Publication statusPublished - 2014
    MoE publication typeA1 Journal article-refereed


    • plasma physics
    • tokamaks
    • microinstabilities


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