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Impact of fast ions and fishbones on core turbulence at rational surfaces via global gyrokinetic GENE simulations.

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Title: Impact of fast ions and fishbones on core turbulence at rational surfaces via global gyrokinetic GENE simulations.
Authors: Brioschi, D.1 (AUTHOR) davide.brioschi@ipp.mpg.de, Di Siena, A.1 (AUTHOR), Bilato, R.1 (AUTHOR), Bottino, A.1 (AUTHOR), Hayward-Schneider, T.1 (AUTHOR), Mishchenko, A.2 (AUTHOR), Poli, E.1 (AUTHOR), Zocco, A.2 (AUTHOR), Jenko, F.1 (AUTHOR)
Source: Nuclear Fusion. 2026, Vol. 66 Issue 7, p1-14. 14p.
Subjects: Fast ions, Plasma turbulence, Plasma stability, Temperature distribution, Plasma instabilities, Plasma dynamics, Surfaces (Physics)
Abstract: In this work, the interplay between fast ions (FIs) and safety factor rational surfaces is studied in a turbulent plasma via global nonlinear gyrokinetic simulations. The fast particle-induced enhancement of shearing structures from turbulence self-interaction is analyzed. Our study takes into account the competition between this mechanism and other FIs effects, i.e. thermal profiles dilution and quasi-resonant interaction. We find the reduction of the zonal modes destabilization threshold caused by FIs (Hahm et al 2023 Phys. Plasmas 30 072501) to be a very effective method to suppress turbulence. Indeed, it leads to the formation of regions where turbulent transport is reduced by 90% of its original value. Furthermore, an n = m = 1 fishbone is driven unstable inside the plasma and its interaction with turbulence is studied. We find the beat-driven zonal structure generated by this mode to further reduce turbulence when its presence does not drastically flatten the thermal profiles. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:In this work, the interplay between fast ions (FIs) and safety factor rational surfaces is studied in a turbulent plasma via global nonlinear gyrokinetic simulations. The fast particle-induced enhancement of shearing structures from turbulence self-interaction is analyzed. Our study takes into account the competition between this mechanism and other FIs effects, i.e. thermal profiles dilution and quasi-resonant interaction. We find the reduction of the zonal modes destabilization threshold caused by FIs (Hahm et al 2023 Phys. Plasmas 30 072501) to be a very effective method to suppress turbulence. Indeed, it leads to the formation of regions where turbulent transport is reduced by 90% of its original value. Furthermore, an n = m = 1 fishbone is driven unstable inside the plasma and its interaction with turbulence is studied. We find the beat-driven zonal structure generated by this mode to further reduce turbulence when its presence does not drastically flatten the thermal profiles. [ABSTRACT FROM AUTHOR]
ISSN:00295515
DOI:10.1088/1741-4326/ae6e54