The 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.

Salewski, M., Nocente, M., Madsen, B., Abramovic, I., Gorini, G., Jacobsen, A., et al. (2019). Diagnostic of fast-ion energy spectra and densities in magnetized plasmas. JOURNAL OF INSTRUMENTATION, 14(5) [10.1088/1748-0221/14/05/C05019].

Diagnostic of fast-ion energy spectra and densities in magnetized plasmas

Nocente M.;Gorini G.;Tardocchi M.;
2019

Abstract

The 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.
Articolo in rivista - Articolo scientifico
Nuclear instruments and methods for hot plasma diagnostics; Computerized Tomography (CT); Computed Radiography (CR)
English
2019
14
5
C05019
none
Salewski, M., Nocente, M., Madsen, B., Abramovic, I., Gorini, G., Jacobsen, A., et al. (2019). Diagnostic of fast-ion energy spectra and densities in magnetized plasmas. JOURNAL OF INSTRUMENTATION, 14(5) [10.1088/1748-0221/14/05/C05019].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/269982
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