Velocity-space tomography of an MeV fast-ion tail generated by three-ion scheme ICRF heating at JET
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 $ _{\mathrm{NBI}}$ – ^3 He three-ion scheme. This reconstruction is b...
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| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
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| Series: | Nuclear Fusion |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1741-4326/addb60 |
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| Summary: | 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 $ _{\mathrm{NBI}}$ – ^3 He 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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| ISSN: | 0029-5515 |