Structure and dynamics of spontaneous and induced ELMs on ASDEX Upgrade

J. Neuhauser, V. Bobkov, G. D. Conway, R. Dux, T. Eich, M. Garcia-Munoz, A. Herrmann, L. D. Horton, A. Kallenbach, S. Kalvin, G. Kocsis, B. Kurzan, P. T. Lang, M. Maraschek, H. W. Mueller, H. D. Murmann, R. Neu, A. G. Peeters, M. Reich, V. RohdeA. Schmid, W. Suttrop, M. Tsalas, E. Wolfrum

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Abstract

In order to assess the contribution of edge localized modes (ELMs) to plasma-wall interaction in future fusion experiments like ITER, a sound experimental database for model validation and extrapolation, and, to be prepared for the unfavourable case, the development of tools for ELM mitigation are required. On ASDEX Upgrade a large amount of experimental information has been accumulated from various diagnostics on the structure and dynamics of natural as well as pellet induced ELMs, and on related wall effects. In this paper a survey of type-I ELM results is given first and recent progress is then described in detail. In between ELMs, strong mode activity is observed in a wide mode number and frequency range, specifically large amplitude (∼20%) low frequency (several kilohertz) fluctuations. The initial dynamic ELM phase is dominated by the rapid growth of helical, low mode number structures rotating in the pedestal E × B direction, while the subsequent saturation and profile erosion phase is more complex and scenario dependent. Bursts of filaments ejected from the hot edge into the scrape-off layer are correlated with primary pedestal mode rotation. After partial edge profile collapse, a quiescent recovery phase is obtained despite substantial residual edge gradients. Pellet induced ELMs behave similarly to spontaneous ones, at least for the smallest pellets available so far.

Original languageEnglish
Article number045005
JournalNuclear Fusion
Volume48
Issue number4
DOIs
Publication statusPublished - ápr. 1 2008

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ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Neuhauser, J., Bobkov, V., Conway, G. D., Dux, R., Eich, T., Garcia-Munoz, M., Herrmann, A., Horton, L. D., Kallenbach, A., Kalvin, S., Kocsis, G., Kurzan, B., Lang, P. T., Maraschek, M., Mueller, H. W., Murmann, H. D., Neu, R., Peeters, A. G., Reich, M., ... Wolfrum, E. (2008). Structure and dynamics of spontaneous and induced ELMs on ASDEX Upgrade. Nuclear Fusion, 48(4), [045005]. https://doi.org/10.1088/0029-5515/48/4/045005