Impurity transport driven by fishbones in MAST

M. Cecconello, O.M. Jones, L. Garzotti, K.G. McClements, M. Carr, S.S. Henderson, S.E. Sharapov, I. Klimek

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Abstract

In MAST, bursting toroidal Alfvén eigenmodes and fishbones are observed to give rise to an asymmetric perturbation to the soft x-ray (SXR) emission close to the magnetic axis which grows and decays on the time scale of the fishbone evolution. As the fishbone nears its maximum amplitude, the SXR emission starts to increase (decrease) at radial positions smaller (larger) than the radial position of the magnetic axis. This trend in the SXR emission persists for a few milliseconds, until the fishbone starts to decay in amplitude and the slower overall trend of the SXR emission once again becomes dominant. A preliminary analysis suggests that the change in the SXR emission is due to the localized accumulation of high-Z impurities, sustained against parallel transport by the effects of fishbones on the fast ion population.
Original languageEnglish
Article number032002
Number of pages8
JournalNuclear Fusion
Volume55
Issue number3
DOIs
Publication statusPublished - 6 Feb 2015

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Keywords

  • spherical tokamaks
  • plasma impurities
  • soft X-ray

Cite this

Cecconello, M., Jones, O. M., Garzotti, L., McClements, K. G., Carr, M., Henderson, S. S., ... Klimek, I. (2015). Impurity transport driven by fishbones in MAST. Nuclear Fusion, 55(3), [032002]. https://doi.org/10.1088/0029-5515/55/3/032002