Conference paper
Diagnostic of fast-ion energy spectra and densities in magnetized plasmas
Department of Physics, Technical University of Denmark1
ASDEX Upgrade Team2
EUROfusion MST1 Team3
University of Milan - Bicocca4
Eindhoven University of Technology5
United Kingdom Atomic Energy Authority6
Plasma Physics and Fusion Energy, Department of Physics, Technical University of Denmark7
Max Planck Institute for Plasma Physics8
Quantum Physics and Information Technology, Department of Physics, Technical University of Denmark9
National Research Council of Italy10
Uppsala University11
...and 1 moreThe measurement of the energy spectra and densities of α-particles and other fast ions are part of the ITER measurement requirements, highlighting the importance of energy-resolved energetic-particle measurements for the mission of ITER. However, it has been found in recent years that the velocity-space interrogation regions of the foreseen energetic-particle diagnostics do not allow these measurements directly.
We will demonstrate this for γ-ray spectroscopy (GRS), collective Thomson scattering (CTS), neutron emission spectroscopy and fast-ion Dα spectroscopy by invoking energy and momentum conservation in each case, highlighting analogies and differences between the different diagnostic velocity-space sensitivities.
Nevertheless, energy spectra and densities can be inferred by velocity-space tomography which we demonstrate using measurements at JET and ASDEX Upgrade. The measured energy spectra agree well with corresponding simulations. At ITER, α-particle energy spectra and densities can be inferred for energies larger than 1.7 MeV by velocity-space tomography based on GRS and CTS.
Further, assuming isotropy of the α-particles in velocity space, their energy spectra and densities can be inferred by 1D inversion of spectral single-detector measurements down to about 300 keV by CTS. The α-particle density can also be found by fitting a model to the CTS measurements assuming the α-particle distribution to be an isotropic slowing-down distribution.
Language: | English |
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Year: | 2019 |
Proceedings: | 5th International Conference Frontiers in Diagnostcs Technologies |
ISSN: | 17480221 |
Types: | Conference paper |
DOI: | 10.1088/1748-0221/14/05/C05019 |
ORCIDs: | Salewski, Mirko , Madsen, Birgitte , Korsholm, Søren Bang , Nielsen, Stefan Kragh , Poulsen, Andreas Feldt Lomholt and Rasmussen, Jesper |