Velocity-space tomography of an MeV fast-ion tail generated by three-ion scheme ICRF heating at JET

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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en

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16

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Nuclear Fusion, Volume 65, issue 7, pp. 1-16

Abstract

Recently-developed methods are used successfully to reconstruct the two-dimensional velocity-space distribution of the energetic minority MeV ion tail created by heating in the ion cyclotron range of frequencies (ICRFs) in the D-D NBI -3He three-ion scheme. This reconstruction is based on neutron emission spectroscopy and gamma-ray spectroscopy measurements of JET plasma 95679. These datasets present challenges in velocity-space tomography which are met by collisional regularisation coupled to a sparsity-promoting regularisation technique. In combination, these capture the energetic ion tail in pitch-angle as well as in energy. Our reconstructions highlight the importance of diagnostics that can probe the plasma with oblique lines-of-sight with respect to the direction of the confining magnetic field. Our inferred fast-ion distribution corroborates experimentally the pitch angle tilt of the energetic ion tail predicted analytically, and by TRANSP simulations, for the three ion ICRF scheme. The synergies between neutral-beam injection and ICRF heating are captured by these diagnostics, and we are able to validate models of electromagnetic ICRF wave heating directly from the experiments.

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Publisher Copyright: © 2025 The Author(s). Published by IOP Publishing Ltd on behalf of the IAEA.

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Reman, B, Järleblad, H, Dong, Y, Eriksson, J, Nocente, M, Kazakov, Y, Lerche, E, Van Eester, D, Dendy, R, Moseev, D, Snicker, A, Rud, M, Schmidt, B, Štancar, I, Valentini, A, Salewski, M & JET Contributors 2025, 'Velocity-space tomography of an MeV fast-ion tail generated by three-ion scheme ICRF heating at JET', Nuclear Fusion, vol. 65, no. 7, 076007, pp. 1-16. https://doi.org/10.1088/1741-4326/addb60