Gamma-ray measurements in D fusion plasma experiments on JET

Using capabilities of the gamma-ray spectrometry, fusion born alpha-particles were studied in recent D-3He plasma experiments on JET. A substantial population of the alpha-particles was generated in the He-3-rich plasma due to the He-3(D, p)He-4 reaction. Fast deuterium ions of the neutral beam injection (NBI) heating were accelerated to MeV energies with three-ion scenario D-(DNBI)-He-3 using radio frequency waves in the ion cyclotron range of frequencies (ICRF). A high reaction rate allowed to measure the alpha-particle production rate and their spatial distribution in the plasma by detecting 16.7-MeV gamma-rays from the He-3(D, y)Li-5 reaction, which is a weak branch of He-3(D, p)He-4 reaction. A branching ratio of gamma-ray transitions to the ground and the first excited states of Li-5 was obtained. Due to the beryllium is a main impurity of JET plasmas, intensive gamma-rays from the Be-9(D, ny)10B, Be-9(D, py)Be-10 and Be-9(a, ny)C-12 reactions were observed. Exploitation of the reaction cross-sections and the Doppler shape analysis (DSA) of gamma-lines in the recorded spectra provided the possibility to reconstruct distribution functions of the confined D-ions and the fusion-born alpha-particles.