|Title||Time-resonant tokamak plasma edge instabilities?|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||A.J Webster, 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, J. Likonen, M. Rubel, JET-EFDA Contributors|
|Journal||Plasma Physics and Controlled Fusion|
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 7-8 ms 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.
|Alternate Title||Plasma Phys. Control. Fusion|
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