Nonlinear electromagnetic interplay between fast ions and ion-temperature-gradient plasma turbulence. (3rd April 2021)

• Record Type: Journal Article
• Authors: Di Siena, A.; Görler, T.; Poli, E.; Bañón Navarro, A.; Biancalani, A.; Bilato, R.; Bonanomi, N.; Novikau, I.; Vannini, F.; Jenko, F.
• Is Part Of: Journal of plasma physics. Volume 87:Number 2(2021)
• Publication Date: 2021-04-03
• Subjects: fusion plasma -- plasma nonlinear phenomena -- plasma instabilities; Plasma (Ionized gases) -- Periodicals; 530.4405
• DOI: 10.1017/S0022377821000362
• Languages: English
• ISSNs: 0022-3778

Abstract

Abstract : In strong electromagnetic regimes, gyrokinetic simulations have linked a substantial ion-scale turbulence stabilization to the presence of supra-thermal particles, capturing qualitatively well the experimental observations in different devices worldwide. An explanation for the underlying physical mechanism responsible for the fast-ion-induced turbulent transport reduction observed in the numerical simulations has been proposed only recently by Di Siena et al. ( Nucl. Fusion, vol. 59, 2019, p. 124001; Nucl. Fusion, vol. 60, 2020, p. 089501). It involves a nonlinear cross-scale coupling (nonlinear interaction involving different modes at different wavenumbers) between ion-temperature-gradient and marginally stable Alfvén eigenmodes, which in turn increases zonal flow activity. In view of an optimization of this turbulence-stabilizing effect, the key parameters controlling the nonlinear cross-scale coupling are here identified. At the same time, these findings provide useful insights for reduced-turbulence models and integrative approaches, which might be trained on the results presented in this paper to grasp the underlying physics and the parameter scaling of the beneficial effects of fast particles on plasma turbulence.