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arXiv · 2512.09243

On How Zonal Fields Suppress Reversed Shear Alfv\'en Eigenmode in Tokamak Plasmas

Ruirui Ma·Pengfei Liu·Liu Chen·Fulvio Zonca·Zhiyong Qiu
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Abstract

Employing both nonlinear gyrokinetic simulations and theoretical analyses, we have discovered the novel result that, with energetic particle dynamics kept linear, the nonlinear suppression and eventual saturation of reversed-shear Alfv\'en eigenmode occur via the downward frequency chirping induced by the beat-driven zonal current. More specifically, as the mode frequency chirps downward, there is enhanced mode conversion to radially propagating electron Landau-damped kinetic Alfv\'en waves; resulting in enhanced convective (radiative) damping and, thereby, its suppression and saturation. Theoretical results are in good agreement with simulations both qualitatively and quantitatively.

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Ruirui Ma, Pengfei Liu, Liu Chen, Fulvio Zonca, Zhiyong Qiu. 2025-12-10. On How Zonal Fields Suppress Reversed Shear Alfv\'en Eigenmode in Tokamak Plasmas. https://arxiv.org/abs/2512.09243

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