Divertor biasing experiments in IMS

An electrostatic method for controlling diverted particle fluxes in a stellarator has been demonstrated. Potentials applied to a defined set of divertor targets (shields) in contact with diverted flux bundles results in redistribution of plasma flow to any given divertor. Examination of the edge magnetic topology shows that ExB drifts just outside the last-closed magnetic surface account for the alteration of the diverted particle flows. Divertor models applied to the Proto-Cleo Stellarator show large changes in the expected divertor structure as a function of the scrape-off-layer thickness. Diagnostics recently installed in preparation for experimental investigation will be described. (author). 8 refs, 2 figs