Abstract Details
Abstracts
Author: James M. Edmiston
Requested Type: Consider for Invited
Submitted: 2026-02-24 08:13:30
Co-authors: M.Fitzgerald, J.Ruiz Ruiz, D.A.Uzdensky, A.A.Schekochihin
Contact Info:
University of Oxford
Park Road
Oxford, OX1 3PU
United Kingdom
Abstract Text:
In magnetic fusion devices, ITG turbulence can be suppressed by Shear Alfvén Wave eigenmodes [1][2]. These interact non-linearly to produce low frequency zonal flows [3], which shear apart turbulent eddies and reduce transport in the core. Secondary instability calculations have been undertaken for this process [4], but quantitative predictions of the transport suppression require a theoretical understanding of the fully-developed turbulent system.
As a first step, coherently-forced weak reduced-magnetohydrodynamic turbulence is studied analytically and numerically in a homogeneous plasma. Modes are produced at the second level of non-linearity with zero frequency and no variation along the magnetic field, which in a gradient-free system correspond to zonal flows. Saturated amplitudes are found analytically as a function of pump wave amplitude. Contrary to previous beliefs [5], this indicates that zonal flows can be generated by Shear Alfvén Waves without compressibility, kinetic effects or complex geometry. This new understanding may help quantify the transport suppression by Alfvén Eigenmodes in future fusion devices.
[1] Di Siena, A., Görler, T., Poli, E., Navarro, A. Bañón, Biancalani, A. & Jenko, F. 2019
Electromagnetic turbulence suppression by energetic particle driven modes. Nuclear Fusion 59 (12), 124001
[2] Mazzi, S. et al 2022
Enhanced performance in fusion plasmas through turbulence suppression by megaelectronvolt ions. Nature Physics 18 (7), 776–782
[3] Ruiz Ruiz, J. et al 2025
Measurement of Zero-Frequency Fluctuations Generated by Coupling between Alfvén Modes in the JET Tokamak. Physical Review Letters 134 (9), 095103
[4] Chen, Liu & Zonca, Fulvio 2016
Physics of Alfvén waves and energetic particles in burning plasmas. Reviews of Modern Physics 88 (1)
[5] Chen, Liu & Zonca, Fulvio 2013
On nonlinear physics of shear Alfvén waves. Physics of Plasmas 20 (5), AIP Publishing
Characterization: 1.0
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