MeV-range velocity-space tomography from gamma-ray and neutron emission spectrometry measurements at JET

Author(s): Salewski, M; Nocente, M; Jacobsen, AS; Binda, F; Cazzaniga, C; Ericsson, G; Eriksson, J; Gorini, G; Hellesen, C; Hjalmarsson, A; Kiptily, VG; Koskela, T; Korsholm, SB; Kurki-Suonio, T; Leipold, F; Madsen, J; Moseev, D; Nielsen, SK; Rasmussen, J; Schneider, M; Sharapov, SE; Stejner, M; Tardocchi, M | Abstract: © 2017 Technical University of Denmark. We demonstrate the measurement of a 2D MeV-range ion velocity distribution function by velocity-space tomography at JET. Deuterium ions were accelerated into the MeV-range by third harmonic ion cyclotron resonance heating. We made measurements with three neutron emission spectrometers and a high-resolution γ-ray spectrometer detecting the γ-rays released in two reactions. The tomographic inversion based on these five spectra is in excellent agreement with numerical simulations with the ASCOT-RFOF and the SPOT-RFOF codes. The length of the measured fast-ion tail corroborates the prediction that very few particles are accelerated above 2 MeV due to the weak wave-particle interaction at higher energies.