Time-resonant tokamak plasma edge instabilities?
2014 (English)In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 56, no 7, 075017- p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2014. Vol. 56, no 7, 075017- p.
tokamak, plasma, stability, ELMs, statistics
IdentifiersURN: urn:nbn:se:kth:diva-148361DOI: 10.1088/0741-3335/56/7/075017ISI: 000338515300018ScopusID: 2-s2.0-84902969835OAI: oai:DiVA.org:kth-148361DiVA: diva2:736360
QC 201408062014-08-062014-08-052014-08-06Bibliographically approved