Velocity-space tomography of the fast-ion distribution function in a fusion plasma is usually a photon-starved tomography method due to limited optical access and signal-to-noise ratio of fast-ion Dα (FIDA) spectroscopy as well as the strive for high-resolution images. In high-definition tomography, prior information makes up for this lack of data. We restrict the target velocity space through the measured absence of FIDA light, impose phase-space densities to be non-negative, and encode the known geometry of neutral beam injection (NBI) sources. We further use a numerical simulation as prior information to reconstruct where in velocity space the measurements and the simulation disagree. This alternative approach is demonstrated for four-view as well as for two-view FIDA measurements. The high-definition tomography tools allow us to study fast ions in sawtoothing plasmas and the formation of NBI peaks at full, half and one-third energy by time-resolved tomographic movies.

Salewski, M., Geiger, B., Jacobsen, A., Hansen, P., Heidbrink, W., Korsholm, S., et al. (2016). High-definition velocity-space tomography of fast-ion dynamics. NUCLEAR FUSION, 56(10) [10.1088/0029-5515/56/10/106024].

High-definition velocity-space tomography of fast-ion dynamics

NOCENTE, MASSIMO;
2016

Abstract

Velocity-space tomography of the fast-ion distribution function in a fusion plasma is usually a photon-starved tomography method due to limited optical access and signal-to-noise ratio of fast-ion Dα (FIDA) spectroscopy as well as the strive for high-resolution images. In high-definition tomography, prior information makes up for this lack of data. We restrict the target velocity space through the measured absence of FIDA light, impose phase-space densities to be non-negative, and encode the known geometry of neutral beam injection (NBI) sources. We further use a numerical simulation as prior information to reconstruct where in velocity space the measurements and the simulation disagree. This alternative approach is demonstrated for four-view as well as for two-view FIDA measurements. The high-definition tomography tools allow us to study fast ions in sawtoothing plasmas and the formation of NBI peaks at full, half and one-third energy by time-resolved tomographic movies.
Articolo in rivista - Articolo scientifico
fast ions; fast-ion D-alpha spectroscopy; neutral beam injection; sawteeth; tokamaks; tomography;
fast ions; fast-ion D-alpha spectroscopy; neutral beam injection; sawteeth; tokamaks; tomography; Nuclear and High Energy Physics; Condensed Matter Physics
English
Salewski, M., Geiger, B., Jacobsen, A., Hansen, P., Heidbrink, W., Korsholm, S., et al. (2016). High-definition velocity-space tomography of fast-ion dynamics. NUCLEAR FUSION, 56(10) [10.1088/0029-5515/56/10/106024].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/146624
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