On the turbulence characterization of the quasicoherent mode in EDA high confinement discharges in ASDEX Upgrade

ORAL

Abstract

Intrinsic ELM-free regimes that combine a high-performance fusion core with a compatible power exhaustion solution are desirable in a fusion reactor. The enhanced D-Alpha (EDA) H-mode is an ELM-free regime that fulfills several requirements for ITER and a DEMO [1,2]. The principal signature of the EDA H-mode is an edge oscillation called quasicoherent mode (QCM) that is believed to prevent the pressure gradient from overcoming the peeling-ballooning boundary. However, the driven instability responsible for the appearance of the QCM is not well understood.

In this contribution, we present the latest experimental results on the turbulence characterization of the QCM in ASDEX Upgrade, mainly focusing on the data from a scanning probe and the thermal helium beam diagnostic in the outer midplane in EDA H-mode discharges. The QCM is localized radially in the pedestal foot, extending to the open field line region [3,4]. The mode is observed with frequency in the range 13-70 kHz and normalized poloidal wavenumber kθρs = 0.018-0.075 [3,4], suggesting ion scale driven instability. The QCM induces radially outward transport across the separatrix, with an anti-correlated cross-phase between density and potential fluctuations in the confined region (a fingerprint of electromagnetic instabilities) and more correlated further out, consistent with a drift-wave [4]. Finally, the experimental observations are compared with initial results from turbulence simulations with the gyrokinetic code GENE.

*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 theEuropean Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them.

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Publication: [1] L. Gil et al. Nucl. Fusion, 60, 054003 (2020)
[2] A. Kallenbach et al. Nucl. Fusion, 61(1):016002 (2020)
[3] J. Kalis et al. Nucl. Fusion 64 016038 (2024)
[4] G. Grenfell et al. Nucl. Fusion. Submitted (2024)

Presenters

  • Gustavo Grenfell

    • Max Planck Institute for Plasma Physics
    • Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany

Authors

  • Gustavo Grenfell

    • Max Planck Institute for Plasma Physics
    • Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany

  • Luis Gil

    • Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal

  • Joey Kalis

    • Max Planck Institute for Plasma Physics

  • Peter Manz

    • Institute of Physics, University of Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald, Germany

  • Tobias Görler

    • Max Planck Institute for Plasma Physics

  • Jiri Adamek

    • Institute of Plasma Physics of the CAS

  • Gregor Birkenmeier

    • Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
    • Max Planck Institute for Plasma Physics

  • Dominik Brida

    • Max Planck Institute for Plasma Physics

  • Garrard D Conway

    • Max Planck Institute for Plasma Physics
    • Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany

  • Thomas Eich

    • Commonwealth Fusion Systems

  • Michael Faitsch

    • Max-Planck-Institute for Plasmaphysics
    • Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
    • Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany

  • Michael Griener

    • Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany

  • Tim Happel

    • Max Planck Institute for Plasma Physics
    • Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany

  • Monica Spolaore

    • Consorzio RFX, 35127, Padova, Italy

  • Carlos Silva

    • Instituto Superior Técnico
    • Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal

  • Ulrich Stroth

    • MPI for Plasma Physics

  • Branka Vanovac

    • MIT
    • MIT PSFC

  • Elisabeth Wolfrum

    • Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
    • Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany