Modifications of the surface of a stainless steel limiter during operation in the T-10 tokamak

Parts of a stainless steel limiter used in the T-10 tokamak for about 1000 discharges have been analyzed by several standard analysis techniques as SEM, EDS, SAM, AES, RBS and SIMS, with respect to modifications of surface structure and chemical composition. Erosion phenomena due to melting and evaporation, arcing, and sputtering could be observed on limiter parts exposed to the plasma flux. In these regions the chemical composition was changed only slightly, whereas in regions shielded by other internal structures of T-10 impurity layers with a thickness up to about 3000 A were deposited. Additionally on the limiter surface there has been found a considerable number of microscopic particles. They seem to originate from different internal components of T-10, as the fixed W/Mo-limiter, a Ti-anode, and Inconel made parts of the vessel.