Explorative studies for the development of fast He beam plasma diagnostics

Modelling calculations for a fast He beam on its way through a tokamak plas ma have been performed at TU Wien. They are based on the collisional-radiat ive ADAS model for He beams which delivers radially resolved population den sity and line intensity profiles for any initial population of a diagnostic He beam and any plasma structure. The effect of the metastable triplet pop ulation in the incident beam on the line emission profiles is shown. A sens itivity study of the optical lines with respect to electron temperature and density has been performed in the plasma edge and core regions. To validat e these model calculations, experiments using fast He beams and beam emissi on spectroscopy have been performed at ASDEX Upgrade (IPP Garching) and JET by injecting He gas into the ion sources of the H- or D-heating beam syste ms, (C) 2001 Elsevier Science B.V. All rights reserved.