Field-Line Localized Destabilization of Ballooning Modes in Three-Dimensional Tokamaks

TitleField-Line Localized Destabilization of Ballooning Modes in Three-Dimensional Tokamaks
Publication TypeJournal Article
Year of Publication2017
AuthorsM. Willensdorfer, T.B Cote, C. Hegna, W. Suttrop, H. Zohm, M. Dunne, E. Strumberger, G. Birkenmeier, S.S Denk, B. Vanovac, F. Mink, N.C Luhmann, ASDEX Upgrade Team
JournalPhysical Review Letters
Volume119
Issue8
Pagination085002
Date PublishedFeb
Abstract

Field-line localized ballooning modes have been observed at the edge of high confinement mode plasmas in ASDEX Upgrade with rotating 3D perturbations induced by an externally applied n = 2 error field and during a moderate level of edge localized mode mitigation. The observed ballooning modes are localized to the field lines which experience one of the two zero crossings of the radial flux surface displacement during one rotation period. The localization of the ballooning modes agrees very well with the localization of the largest growth rates from infinite-n ideal ballooning stability calculations using a realistic 3D ideal magnetohydrodynamic equilibrium. This analysis predicts a lower stability with respect to the axisymmetric case. The primary mechanism for the local lower stability is the 3D distortion of the local magnetic shear

DOI10.1103/PhysRevLett.119.085002
Division

FP

Department

PEPD

PID

1d6ed9bafa05f7cdb28d82d1f88a7a70

Alternate TitlePhys. Rev. Lett.
LabelOA

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