Low frequency sawtooth precursor activity in ASDEX Upgrade

G. Papp, G. I. Pokol, G. Por, A. Magyarkuti, N. Lazányi, L. Horváth, V. Igochine, M. Maraschek

Research output: Contribution to journalArticle

15 Citations (Scopus)


This paper describes the precursor activity observed in the ASDEX Upgrade tokamak before sawtooth crashes in various neutral beam heated plasmas, utilizing the soft x-ray diagnostic. In addition to the well-known (m, n) = (1,1) internal kink mode and its harmonics, a lower frequency mode is studied in detail. Power modulation of this mode is found to correlate with the power modulation of the (1, 1) kink mode in the quasistationary intervals indicating possible nonlinear interaction. Throughout the studied sawtooth crashes, the power of the lower frequency mode rose by several orders of magnitude just before the crash. In addition to its temporal behaviour, its spatial structure was estimated and the most likely value was found to be (1, 1). A possible role of this mode in the mechanism of the sawtooth crash is discussed.

Original languageEnglish
Article number065007
JournalPlasma Physics and Controlled Fusion
Issue number6
Publication statusPublished - Jun 2011

ASJC Scopus subject areas

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

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    Papp, G., Pokol, G. I., Por, G., Magyarkuti, A., Lazányi, N., Horváth, L., Igochine, V., & Maraschek, M. (2011). Low frequency sawtooth precursor activity in ASDEX Upgrade. Plasma Physics and Controlled Fusion, 53(6), [065007]. https://doi.org/10.1088/0741-3335/53/6/065007