Generation and observation of fast deuterium ions and fusion-born alpha particles in JET D- 3He plasmas with the 3-ion radio-frequency heating scenario

Massimo Nocente, Yevgen Kazakov, J. Garcia, Vasily Kiptily, Jozef Ongena, Mykola Dreval, Michael Fitzgerald, Sergei E Sharapov, Žiga Štancar, Henri Weisen, Yuriy Baranov, Andreas Bierwage, Teddy Craciunescu, Andrea Dal Molin, Elena de la Luna, Remi Dumont, Pierre Dumortier, Jacob Eriksson, Luca Giacomelli, Carine GiroudVictor Goloborodko, Giuseppe Gorini, Evgeniy Khilkevitch, Krassimir K Kirov, Margarita Iliasova, Philippe Jacquet, Philipp Lauber, Ernesto A Lerche, Mervi Mantsinen, Alberto Mariani, Samuele Mazzi, Fernando Nabais, Maria Filomena Ferreira Nave, Henry James Churston Oliver, Enrico Panontin, Davide Rigamonti, Arne Erik Sahlberg, Mirko Salewski, A. E. Shevelev, Kouji Shinohara, Paula Sirén, Shuhei Sumida, Marco Tardocchi, Dirk Van Eester, Jari Varje, Andrej Zohar

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Dedicated experiments to generate energetic D ions and D-3He fusion-born alpha particles were performed at the Joint European Torus (JET) with the ITER-like wall (ILW). Using the 3-ion D-(DNBI)-3He radio frequency (RF) heating scenario, deuterium ions from neutral beam injection (NBI) were accelerated in the core of mixed D-3He plasmas to higher energies with ion cyclotron resonance frequency (ICRF) waves, in turn leading to a core-localized source of alpha particles. The fast ion distribution of RF-accelerated D-NBI ions was controlled by varying the ICRF and NBI power (PICRF≈4-6MW, PNBI≈ 3-20MW), resulting in rather high D-D neutron (≈1•1016 s-1) and D-3He alpha rates (≈2•1016 s-1) at moderate input heating power. Theory and TRANSP analysis show that large populations of co-passing MeV range D ions were generated using the D-(DNBI)-3He 3-ion ICRF scenario. This important result is corroborated by several experimental observations, in particular gamma-ray measurements. The developed experimental scenario at JET provides unique conditions for probing several aspects of future burning plasmas, such as the contribution from MeV range ions to global confinement, but without introducing tritium. Dominant fast-ion core electron heating with Ti≈Te and a rich variety of fast-ion driven Alfvén eigenmodes (AEs) were observed in these D-3He plasmas. The observed AE activities do not have a detrimental effect on the thermal confinement and, in some cases, may be driven by the fusion born alpha particles. A strong continuous increase in neutron rate was observed during long-period sawteeth (>1s), accompanied by the observation of reversed shear AEs, which implies that a non monotonic q profile was systematically developed in these plasmas, sustained by the large fast-ion populations generated by the 3-ion ICRF scenario.
Original languageEnglish
Article number124006
JournalNuclear Fusion
Volume60
Issue number12
Number of pages10
ISSN0029-5515
DOIs
Publication statusPublished - 2020

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