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A novel measurement of marginal Alfvén eigenmode stability during high power auxiliary heating in JET

Authors
  • Tinguely, R.A.1
  • Fil, N.2
  • Puglia, P.G.3
  • Dowson, S.2
  • Porkolab, M.1
  • Guillemot, V.4
  • Podestà, M.5
  • Baruzzo, M.2
  • Dumont, R.6
  • Fasoli, A.3
  • Fitzgerald, M.2
  • Kazakov, Ye.O.7
  • Nave, M.F.F.8
  • Nocente, M.9, 10
  • Ongena, J.7
  • Sharapov, S.E.2
  • Štancar, Ž.11
  • JET Contributors,
  • 1 Massachusetts Institute of Technology, United States of America
  • 2 Culham Centre for Fusion Energy, United Kingdom , (United Kingdom)
  • 3 Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland , (Switzerland)
  • 4 Ecole Supérieure de Physique et de Chimie Industrielles de la Ville de Paris, France , (France)
  • 5 Princeton Plasma Physics Laboratory, United States of America
  • 6 CEA, France , (France)
  • 7 LPP-ERM/KMS, Belgium , (Belgium)
  • 8 Univ. de Lisboa, Portugal , (Portugal)
  • 9 Universitá di Milano-Bicocca, Italy , (Italy)
  • 10 National Research Council, Italy , (Italy)
  • 11 Jožef Stefan Institute, Slovenia , (Slovenia)
Type
Published Article
Journal
Nuclear Fusion
Publisher
IOP Publishing
Publication Date
Apr 22, 2022
Volume
62
Issue
7
Identifiers
DOI: 10.1088/1741-4326/ac3c84
Source
ioppublishing
Keywords
Disciplines
  • Paper
License
Unknown

Abstract

The interaction of Alfvén eigenmodes (AEs) and energetic particles is one of many important factors determining the success of future tokamaks. In JET, eight in-vessel antennas were installed to actively probe stable AEs with frequencies ranging 25–250 kHz and toroidal mode numbers |n| < 20. During the 2019–2020 deuterium campaign, almost 7500 resonances and their frequencies f 0, net damping rates γ < 0, and toroidal mode numbers were measured in almost 800 plasma discharges. From a statistical analysis of this database, continuum and radiative damping are inferred to increase with edge safety factor, edge magnetic shear, and when including non-ideal effects. Both stable AE observations and their associated damping rates are found to decrease with |n|. Active antenna excitation is also found to be ineffective in H-mode as opposed to L-mode; this is likely due to the increased edge density gradient’s effect on accessibility and ELM-related noise’s impact on mode identification. A novel measurement is reported of a marginally stable, edge-localized ellipticity-induced AE probed by the antennas during high-power auxiliary heating (ion cyclotron resonance heating and neutral beam injection) up to 25 MW. NOVA-K kinetic-MHD simulations show good agreement with experimental measurements of f 0, γ, and n, indicating the dominance of continuum and electron Landau damping in this case. Similar experimental and computational studies are planned for the recent hydrogen and ongoing tritium campaigns, in preparation for the upcoming DT campaign.

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