Measurement of Zero-Frequency Fluctuations Generated by Coupling between Alfvén Modes in the JET Tokamak

Measurement of Zero-Frequency Fluctuations Generated by Coupling between Alfvén Modes in the JET Tokamak

Physical Review Letters

10.1103/PhysRevLett.134.095103

https://doi.org/10.1103/PhysRevLett.134.095103

J. Ruiz Ruiz, J. Garcia, M. Barnes, M. Dreval, C. Giroud, V. H. Hall-Chen, M. R. Hardman, J. C. Hillesheim, Y. Kazakov, S. Mazzi, B. S. Patel, F. I. Parra, A. A. Schekochihin, Ž. Štancar,

07 March 2025

Ruiz Ruiz, J., Garcia, J., Barnes, M., Dreval, M., Giroud, C., Hall-Chen, V. H., Hardman, M. R., Hillesheim, J. C., Kazakov, Y., Mazzi, S., Patel, B. S., Parra, F. I., Schekochihin, A. A., & Štancar, Ž. (2025). Measurement of Zero-Frequency Fluctuations Generated by Coupling between Alfvén Modes in the JET Tokamak. Physical Review Letters, 134(9). https://doi.org/10.1103/physrevlett.134.095103

We report the first experimental detection of a zero-frequency fluctuation that is pumped by an Alfvén mode in a magnetically confined plasma. Core-localized Alfvén 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 Alfvén modes, and is correlated with an increase in the deep core ion temperature, temperature gradient, confinement factor H89,P, and a reduction in the main ion heat diffusivity. Despite the energetic particle transport induced by the Alfvén eigenmodes, the generation of a zero-frequency fluctuation that can suppress the turbulence leads to an overall improvement of confinement. Published by the American Physical Society 2025

Attribution 4.0 International (CC BY 4.0)

This research / project is supported by the Agency for Science, Technology and Research - Green Seed Fund
Grant Reference no. : C231718014

This research / project is supported by the Agency for Science, Technology and Research - Manufacturing, Trade, and Connectivity Young Individual Research Grants
Grant Reference no. : M23M7c0127

https://oar.a-star.edu.sg/communities-collections/articles/21868

0031-9007
1079-7114

Institute of High Performance Computing 

https://doi.org/10.1103/PhysRevLett.134.095103