Ion Beam Analysis of Surface Modifications in Tokamaks

This paper briefly reviews the use of ion beam techniques to study surface modification of samples exposed to tokamak plasma discharges. Primary emphasis is given to a continuing study of samples exposed at the first wall of the Princeton Large Torus (PLT) tokamak throughout its operating life. Both impurity flow and hydrogen recycle effects are investigated. Laboratory hydrogen implantations at 200-400 eV suggest a method to determine the mean ion temperature at the wall from the hydrogen saturation trapping dependences in Si samples.