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)

    Abstract

    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
    Volume56
    Issue number7
    DOIs
    Publication statusPublished - 2014
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    Plasma stability
    probability density functions
    Probability density function
    Joint European Torus
    Plasmas
    Plasma confinement
    plasma control
    magnetohydrodynamic stability
    Real time control
    Beam plasma interactions
    resonant frequencies
    Natural frequencies
    intervals
    Control systems
    causes
    interactions

    Keywords

    • plasma physics
    • tokamaks
    • microinstabilities

    Cite this

    Webster, A. J., Dendy, R. O., Calderon, F. A., Chapman, S. C., Delabie, E., Dodt, D., ... Contributors, JET. EFDA. (2014). Time-resonant tokamak plasma edge instabilities? Plasma Physics and Controlled Fusion, 56(7). https://doi.org/10.1088/0741-3335/56/7/075017
    Webster, A.J. ; Dendy, R.O. ; Calderon, F.A. ; Chapman, S.C. ; Delabie, E. ; Dodt, D. ; Felton, R. ; Todd, T.N. ; Maviglia, F. ; Morris, J. ; Riccardo, V. ; Alper, B. ; Brezinsek, S. ; Coad, P. ; Likonen, Jari ; Rubel, M. ; Contributors, JET EFDA. / Time-resonant tokamak plasma edge instabilities?. In: Plasma Physics and Controlled Fusion. 2014 ; Vol. 56, No. 7.
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    title = "Time-resonant tokamak plasma edge instabilities?",
    abstract = "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.",
    keywords = "plasma physics, tokamaks, microinstabilities",
    author = "A.J. Webster and R.O. Dendy and F.A. Calderon and S.C. Chapman and E. Delabie and D. Dodt and R. Felton and T.N. Todd and F. Maviglia and J. Morris and V. Riccardo and B. Alper and S. Brezinsek and P. Coad and Jari Likonen and M. Rubel and Contributors, {JET EFDA}",
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    Webster, AJ, Dendy, RO, Calderon, FA, Chapman, SC, Delabie, E, Dodt, D, Felton, R, Todd, TN, Maviglia, F, Morris, J, Riccardo, V, Alper, B, Brezinsek, S, Coad, P, Likonen, J, Rubel, M & Contributors, JETEFDA 2014, 'Time-resonant tokamak plasma edge instabilities?', Plasma Physics and Controlled Fusion, vol. 56, no. 7. https://doi.org/10.1088/0741-3335/56/7/075017

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

    In: Plasma Physics and Controlled Fusion, Vol. 56, No. 7, 2014.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Time-resonant tokamak plasma edge instabilities?

    AU - Webster, A.J.

    AU - Dendy, R.O.

    AU - Calderon, F.A.

    AU - Chapman, S.C.

    AU - Delabie, E.

    AU - Dodt, D.

    AU - Felton, R.

    AU - Todd, T.N.

    AU - Maviglia, F.

    AU - Morris, J.

    AU - Riccardo, V.

    AU - Alper, B.

    AU - Brezinsek, S.

    AU - Coad, P.

    AU - Likonen, Jari

    AU - Rubel, M.

    AU - Contributors, JET EFDA

    PY - 2014

    Y1 - 2014

    N2 - 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.

    AB - 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.

    KW - plasma physics

    KW - tokamaks

    KW - microinstabilities

    U2 - 10.1088/0741-3335/56/7/075017

    DO - 10.1088/0741-3335/56/7/075017

    M3 - Article

    VL - 56

    JO - Plasma Physics and Controlled Fusion

    JF - Plasma Physics and Controlled Fusion

    SN - 0741-3335

    IS - 7

    ER -

    Webster AJ, Dendy RO, Calderon FA, Chapman SC, Delabie E, Dodt D et al. Time-resonant tokamak plasma edge instabilities? Plasma Physics and Controlled Fusion. 2014;56(7). https://doi.org/10.1088/0741-3335/56/7/075017