Gamma-ray spectroscopy measurements of confined fast ions on ASDEX Upgrade

Evidence of gamma-ray emission from fast ions in ASDEX Upgrade (AUG) is presented. The plasma scenarios developed for the experiments involve deuteron or proton acceleration. The observed gamma-ray emission level induced by energetic protons is used to determine the effective tail temperature of the proton distribution function that can be compared with neutral particle analyser measurements. More generally the measured emission rate is used to assess the confinement of protons with energies < 400 keV in discharges affected by toroidal Alfven eigenmode instabilities. The derived information on confined ions is combined with observations made with the AUG fast ion loss detector.