Plasma potential control: initial results from tandem mirror experiment-upgrade

Initial plasma potential control experiments used plates in the end fan, insulated from the end walls of TMX-U, which mapped along field lines to the plasma core (r/sub c/ less than or equal to 12.9 cm). Measurements in which these plates are shorted to ground during plugging demonstrate that floating the plates increases the buildup rate of the central cell plasma, steepens the core density profile, and affects the plasma throughout the entire cross section. Floating the plates decreases the ion radial transport rate in the core by a factor of at least 1.5. Because of these encouraging results, in the next series of experiments more plates will be added, extending to a larger radius (r/sub c/ less than or equal to 19.4 cm)