In the present work conducted at the TOKAMAK experiment ASDEX (axial symmetrical divertor experiment) an optimization of the neutral particle diagnostics was carried out in order to derive reliable ion temperatures from the neutral particle flux, and to establish radial profiles for all important discharge scenaria. Separating high-energetic and non-thermal contributions, relative errors in ion temperature determination could be limited to #+-# 10%, excluding at the same time systematic errors. Based on these experimental and theoretical studies, the local ion energy transport has been analyzed. Results are in line with the basic equations of the neoclassic theory. (WEN)SIGLEAvailable from TIB Hannover: RA 71(III/198) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman