Edge effects during DIII-D divertor biasing

Results of experiments with a toroidal ring bias electrode in contact with the single-null diverter scrape-off layer (SOL) in the DIII-D tokamak are reviewed, and new results and analysis are presented. Topics included are: current flow in the SOL and diverter private flux; SOL density resistance; driven SOL and diverter E x B plasma flows; bias-aided diverter exhaust; SOL density control and impurity shielding; ELM effects on SOL electrical circuit; diverter and SOL heat flux modification; effect of DIII-D formation by the magnetized divertor electrode.