Influence of highly charged impurities on ion temperatures measured with active-beam plasma diagnostics

Abstract
The presence of highly charged impurity ions in a (tokamak) plasma can be very disturbing if one wants to apply active-beam scattering diagnostics, for instance, for the measurement of the local ion temperature, since it is nearly impossible to separate particles scattered by the main plasma constituent from those scattered by the impurity ions. In this work it is shown, by making use of already published theoretical results of the electron-loss probability as a function of impact parameter, that not only for H, but also for He injected neutrals, the effect of impurity ions on the relevant energy distribution of scattered neutrals is negligible.