Nonlinear magnetohydrodynamic modeling of current-drive-induced sawtooth-like crashes in the W7-X stellarator

Sawtooth-like core electron temperature crashes have been observed in W7-X experiments with electron cyclotron current drive. We present nonlinear single-fluid magnetohydrodynamic simulations of this phenomenon using the newly developed stellarator modeling capability of the M3D-C1 code. The near-ax...

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Bibliographic Details
Published in:Physics of plasmas 2023-03, Vol.30 (3)
Main Authors: Zhou, Yao, Aleynikova, K., Ferraro, N. M.
Format: Article
Language:English
Subjects:
Amplitudes
Crashes
Cyclotrons
Electron energy
Magnetohydrodynamic simulation
Modelling
Plasma physics
Resonance
Stellarators
Temperature profiles
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Summary:Sawtooth-like core electron temperature crashes have been observed in W7-X experiments with electron cyclotron current drive. We present nonlinear single-fluid magnetohydrodynamic simulations of this phenomenon using the newly developed stellarator modeling capability of the M3D-C1 code. The near-axis current drive gives rise to two ι = 1 resonances in the equilibrium rotational transform profile so that two consecutive (1, 1) internal kink modes are seen in the simulations. A small-amplitude crash at the inner resonance occurs first, which may correspond to the sawtooth precursors observed in the experiments. A bigger crash at the outer resonance then flattens the core temperature profile, which shows semi-quantitative agreements with experimental measurements on certain metrics such as the crash amplitude and the inversion radius of the temperature change. These results illustrate a likely mechanism of the current-drive-induced sawtooth-like crashes in W7-X and, to some extent, validate the stellarator modeling capability of M3D-C1.
ISSN:1070-664X
1089-7674
DOI:10.1063/5.0136654