EROSION AND DEPOSITION OF METALS AND CARBON IN THE DIII-D DIVERTOR

Net erosion rates at the outer strike point of the DIII-D divertor pla sma were measured for several materials during quiescent H-mode operat ion with deuterium plasmas. Materials examined include graphite, beryl lium, tungsten, vanadium and molybdenum, For graphite, net erosion rat es up to 4 nm/s were found, Erosion rates for the metals were much sma ller than for carbon, Ion fluxes from Langmuir probe measurements were used to predict gross erosion by sputtering. Measured net erosion was smaller than predicted gross erosion, Transport of metal atoms by the plasma across the divertor surface was also examined. Light atoms wer e transported farther than heavy atoms as predicted by impurity transp ort models.