Measurement of zero-frequency fluctuations generated by coupling between Alfvén modes in the JET tokamak

ORAL

Abstract

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 bidirectional 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, and confinement factor $H_{89,P}$. 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.

*This work has been supported by the Engineering and Physical Sciences Research Council (EPSRC) under grant numbers EP/W026341/1 and EP/R034737/1. The work of A.A.S. was also supported in part by the STFC grant STW000903/1 and by the Simons Foundation via a Simons Investigator Award. V. H. Hall-Chen was partly funded by an A*STAR Green Seed Fund, C231718014, and a YIRG, M23M7c0127. This work was supported by the U.S. Department of Energy under contract number DE-AC02-09CH11466. The United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No 101052200 — EUROfusion). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them.

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Presenters

  • Juan Ruiz Ruiz

    • University of Oxford
    • Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3NP, U.K.

Authors

  • Juan Ruiz Ruiz

    • University of Oxford
    • Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3NP, U.K.

  • Jeronimo Garcia

    • CEA, IRFM
    • CEA, IRFM, F-13108 Saint Paul-lez-Durance, France
    • CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France

  • Michael Barnes

    • Rudolf Peierls Centre for Theoretical Physics, University of Oxford, OX1 3NP, UK

  • Mykola Dreval

    • National Science Center Kharkiv Institute of Physics and Technology, 1 Akademichna Str., Kharkiv 61108

  • Carine Giroud

    • United Kingdom Atomic Energy Authority, Culham Campus, Abingdon, UK
    • United Kingdom Atomic Energy Authority, Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxon, OX14 3DB, UK
    • UKAEA (United Kingdom Atomic Energy Authority), Culham Campus, Abingdon, Oxfordshire, OX14 3DB, UK

  • Valerian H Hall-Chen

    • Institute of High Performance Computing, A*STAR
    • Institute of High Performance Computing, Agency for Science, Technology, and Research (A*STAR), Singapore 138632, Singapore

  • michael R hardman

    • Tokamak Energy Ltd, 173 Brook Drive, Milton Park, Abingdon, OX14 4SD, United Kingdom

  • Jon C Hillesheim

    • Commonwealth Fusion Systems

  • Yevgen Kazakov

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

  • Samuele Mazzi

    • CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France

  • Bhavin S Patel

    • UKAEA - United Kingdom Atomic Energy Authority
    • UK Atomic Energy Authority

  • Felix I Parra

    • Princeton Plasma Physics Laboratory

  • Alexander A Schekochihin

    • University of Oxford

  • Ziga Stancar

    • United Kingdom Atomic Energy Authority, Culham Science Centre, Abingdon, Oxon OX14 3DB
    • United Kingdom Atomic Energy Authority, Culham Science Centre, Abingdon, UK
    • UKAEA (United Kingdom Atomic Energy Authority), Culham Campus, Abingdon, Oxfordshire, OX14 3DB, UK