Bifurcations of the magnetic axis and the alternating-hyperbolic sawtooth

Bifurcations of the magnetic axis and the alternating-hyperbolic sawtooth

We present a sawtooth model that explains observations where the central safety factor, q0, stays well below one, which is irreconcilable with current models that predict a reset to q0 = 1 after the crash. We identify the structure of the field around the magnetic axis with elements of the Lie group...

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Bibliographic Details
Published in:Nuclear fusion 2020-08, Vol.60 (8), p.84005
Main Authors: Smiet, C.B., Kramer, G.J., Hudson, S.R.
Format: Article
Language:eng
Subjects:
ideal MHD
magnetic topology
MHD stability
sawtooth oscillation
Online Access:Get full text
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Summary:We present a sawtooth model that explains observations where the central safety factor, q0, stays well below one, which is irreconcilable with current models that predict a reset to q0 = 1 after the crash. We identify the structure of the field around the magnetic axis with elements of the Lie group SL(2, R) and find a transition to an alternating-hyperbolic geometry when q0 = 2/3. This transition is driven by an ideal MHD instability and leads to a chaotic magnetic field near the axis.
ISSN:0029-5515
1741-4326