BIASED H-MODE EXPERIMENTS IN PHAEDRUS-T

Inserting a positively biased electrode to just inside the Phaedrus-T tokamak limiter results in typical H mode behaviour (i.e. H-alpha or D -alpha drop, density rise, increase in stored energy, profile steepeni ng, and reduction of edge turbulence and radial transport) in deuteriu m, hydrogen and helium discharges. H-alpha or D-alpha emission suggest s that the improvement in particle confinement with H mode is poloidal ly asymmetric, with the greatest improvement occurring on the low fiel d side. The radial conductivity is examined and measured values are co mpared with theory.