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arXiv · 2010.14839

New high-confinement regime with fast ions in the core of fusion plasmas

A. Di Siena·R. Bilato·T. Görler·A. Bañón Navarro·E. Poli·V. Bobkov·D. Jarema·E. Fable·C. Angioni·Ye. O. Kazakov·R. Ochoukov·P. Schneider·M. Weiland·F. Jenko·the ASDEX Upgrade Team
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Abstract

The key result of the present work is the theoretical prediction and observation of the formation of a new type of transport barrier in fusion plasmas, called F-ATB (fast ion-induced anomalous transport barrier). As demonstrated through state-of-the-art global electrostatic and electromagnetic simulations, the F-ATB is characterized by a full suppression of the turbulent transport - caused by strongly sheared, axisymmetric $E \times B$ flows - and an increase of the neoclassical counterpart, albeit keeping the overall fluxes at significantly reduced levels. The trigger mechanism is shown to be a mainly electrostatic resonant interaction between supra-thermal particles, generated via ion-cyclotron-resonance heating, and plasma micro-turbulence. These findings are obtained by realistic simulations of the ASDEX Upgrade discharge $\#36637$ - properly designed to maximized the beneficial role of the wave-particle resonance interaction - which exhibits the expected properties of improved confinement produced by energetic particles.

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A. Di Siena, R. Bilato, T. Görler, A. Bañón Navarro, E. Poli, V. Bobkov, D. Jarema, E. Fable, C. Angioni, Ye. O. Kazakov, R. Ochoukov, P. Schneider, M. Weiland, F. Jenko, the ASDEX Upgrade Team. 2020-10-28. New high-confinement regime with fast ions in the core of fusion plasmas. https://doi.org/10.1103/physrevlett.127.025002

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