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Tearing mode formation induced by internal crash events at different β N

Author
Abstract

Tearing mode formation after internal crash events like sawteeth or fishbones is one of the most important MHD processes that results in a big island structure and associated confinement degradation. The process implies magnetic reconnection at the rational surface, which has been investigated in great detail in the ASDEX Upgrade tokamak. Using direct local measurements, it is found that the crash leads to the formation of an ideal kink mode with large saturated amplitude at the resonant surface immediately after the sawtooth crash. This kink mode transforms into a tearing mode on a much longer timescale than the crash itself. The ideal kink mode, formed at the resonant surface after the crash, provides the driving force for the magnetic reconnection. The conversion of the ideal kink mode into a tearing mode after the internal crash is similar for various values of plasma rotation and normalized pressure.

Year of Publication
2017
Journal
Nuclear Fusion
Volume
57
Issue
3
Number of Pages
036015
URL
http://pubman.mpdl.mpg.de/pubman/item/escidoc:2398199:6/component/escidoc:2401513/Igochine_Tearing.pdf
DOI
10.1088/1741-4326/aa4fb9
PId
c6df82450ccb1327528ac6de28bc9dfe
Alternate Journal
Nucl. Fusion
Label
OA
Journal Article
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