EROSION REDEPOSITION ANALYSIS OF THE DIII-D DIVERTOR

Carbon and tungsten sputtering and transport in the DIII-D divertor is analyzed with the impurity transport codes REDEP and WBC. Analysis is carried out for a recent DiMES experiment in which a carbon sample wi th a tungsten marker in the center was exposed to six well controlled ELM-free plasma discharges. WBC analysis predicts a high rate of ioniz ation of tungsten neutrals within the sheath and subsequent redepositi on on the DiMES sample. Qualitative comparison of the tungsten redepos ited flux agrees well with measurements. REDEP analysis of net carbon erosion shows good agreement with measured data on the outboard side o f DiMES and poor agreement on the inboard side.