On How Zonal Fields Suppress Reversed Shear Alfv\'en Eigenmode in Tokamak Plasmas
Plasma Physics
2025-12-11 v1
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.
Keywords
Cite
@article{arxiv.2512.09243,
title = {On How Zonal Fields Suppress Reversed Shear Alfv\'en Eigenmode in Tokamak Plasmas},
author = {Ruirui Ma and Pengfei Liu and Liu Chen and Fulvio Zonca and Zhiyong Qiu},
journal= {arXiv preprint arXiv:2512.09243},
year = {2025}
}