Measurement of zero-frequency fluctuations generated by coupling between Alfven modes in the JET tokamak
Abstract
We report the first experimental detection of a zero-frequency fluctuation that is pumped by an Alfv\`en mode in a magnetically confined plasma. Core-localized bidirectional Alfv\`en modes of frequency inside the toroidicity-induced gap (and its harmonics) exhibit three-wave coupling interactions with a zero-frequency fluctuation. The observation of the zero-frequency fluctuation is consistent with theoretical and numerical predictions of zonal modes pumped by Alfv\'en modes, and is correlated with an increase in the deep core ion temperature, temperature gradient, and confinement factor . Despite the energetic particle transport induced by the Alfv\`en eigenmodes, the generation of a zero-frequency fluctuation that can suppress the turbulence leads to an overall improvement of confinement.
Cite
@article{arxiv.2407.01255,
title = {Measurement of zero-frequency fluctuations generated by coupling between Alfven modes in the JET tokamak},
author = {Juan Ruiz Ruiz and Jeronimo Garcia and Michael Barnes and Mykola Dreval and Carine Giroud and Valerian H. Hall-Chen and Michael R. Hardman and Jon C. Hillesheim and Yevgen Kazakov and Samuele Mazzi and Felix I. Parra and Bhavin S. Patel and Alexander A. Schekochihin and Ziga Stancar and the JET Contributors and the EUROfusion Tokamak Exploitation Team},
journal= {arXiv preprint arXiv:2407.01255},
year = {2025}
}