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Fast ion-induced transport barriers in global gyrokinetic simulations

ORAL · Invited

Abstract

In this contribution, we discuss global gyrokinetic simulations predicting a possible new high-confinement regime in fusion plasmas, sustained via a novel type of transport barrier called F-ATB (fast ion-induced anomalous transport barrier) [1]. More specifically, we performed global GENE [2, 3] simulations with realistic ion-to-electron mass ratio, collisions, electromagnetic effects, and fast ions modelled with realistic background distributions and profiles of a properly designed ASDEX Upgrade plasma discharge with substantial ion-cyclotron-resonance-heating (ICRH). The trigger mechanism responsible for the F-ATB generation is shown to be a recently discovered wave-particle resonance interaction between supra-thermal particles and ion-scale plasma turbulence [4, 5, 6]. This interaction can strongly affect the free energy content of the ITG instabilities and lead to a transport barrier [1]. Signatures of these beneficial fast ion effects have been observed at ASDEX Upgrade [1], JET [7] and are also expected for W7-X [6] and during the ramp-up phase of an ITER [4] standard scenario. 

To gain further physics understanding and to envisage possible experimental actuators for future experiments, we present results exploring the parameter space and physical conditions for the F-ATB formation by performing a systematic study with a series of global GENE simulations. Here, a particular emphasis is given to the transport barrier width and its localization by scanning over different energetic particle profiles. 

The last part of this contribution concerns an exploration study on the existence of F-ATB in SPARC H-mode plasmas at reduced field and with 25 MW of ICRH heating. This is accomplished with a ladder-like approach made of linear and nonlinear GENE simulations. These findings can therefore be considered an important step along with understanding and optimizing nowadays magnetic confinement based fusion experiments as well as improving predictions for future devices.

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Publication: [1] A. Di Siena et al., Accepted Phys. Rev. Lett. 127, 025002 (2021).<br>[2] F. Jenko et al., Phys. Plasmas 7, 1904 (2000).<br>[3] T. Görler et al., J. Comput. Phys. 230, 7053, (2011).<br>[4] A. Di Siena et al., Nucl. Fusion 58 054002 (2018). <br>[5] A. Di Siena et al. Phys. Plasmas 26 052504 (2019). <br>[6] A. Di Siena et al., Phys. Rev. Lett 125 105002 (2020).<br>[7] N. Bonanomi et al., Nucl. Fusion 58 056025 (2018).

Presenters

  • Alessandro Di Siena

    The University of Texas at Austin

Authors

  • Alessandro Di Siena

    The University of Texas at Austin

  • Roberto Bilato

    Max Planck Institute for Plasma Physics

  • Tobias Görler

    Max-Planck-Institut für Plasmaphysik, Garching, Germany, Max Planck Institute for Plasma Physics

  • Alejandro Bañón Navarro

    Max Planck Institute for Plasma Physics

  • Emanuele Poli

    Max Planck Institute for Plasma Physics

  • Vladimir Bobkov

    Max Planck Institute for Plasma Physics

  • Denis Jarema

    Max Planck Institute for Plasma Physics

  • Emiliano Fable

    Max-Planck-Institute for Plasma Physics, Max Planck Institute for Plasma Physics

  • Clemente Angioni

    Max Planck Institute for Plasma Physics, Garching, Germany, Max Planck Institute for Plasma Physics

  • Yevgen Kazakov

    LPP-ERM/KMS, Belgium, Laboratory for Plasma Physics, LPP-ERM/KMS, TEC Partner, Brussels 1000, Belgium

  • Roman Ochoukov

    Max Planck Institute for Plasma Physics

  • Philip A Schneider

    Max-Planck-Institut für Plasmaphysik, Garching, Germany, Max Planck Institute for Plasma Physics, Garching, Germany, Max Planck Institute for Plasma Physics

  • Markus Weiland

    Max Planck Institute for Plasma Physics

  • Pablo Rodriguez-Fernandez

    Massachusetts Institute of Technology MI, MIT PSFC, Massachusetts Institute of Technology MIT, MIT, Massachusetts Institute of Technology, MIT Plasma Science and Fusion Center, Cambridge, MA02139, USA

  • Nathan T Howard

    Massachusetts Institute of Technology MIT, MIT PSFC, Massachusetts Institute of Technology MI

  • John C Wright

    Massachusetts Institute of Technology MIT, Massachusetts Institute of Technology MI, MIT PSFC

  • Martin J Greenwald

    Massachusetts Institute of Technology MIT, MIT Plasma Science and Fusion Center, PSFC

  • Franl Jenko

    Max Planck Institute for Plasma Physics, 85748 Garching, Germany, University of Texas at Austin, Max Planck Institute for Plasma Physics

  • the ASDEX Upgrade Team

    Max-Planck-Institut für Plasmaphysik, Garching, Germany, Max Planck Institute for Plasma Physics