MEASUREMENT OF PLASMA ROTATION VELOCITIES WITH ELECTRODE BIASING IN THE SASKATCHEWAN TORUS-MODIFIED (STOR-M) TOKAMAK

In the Saskatchewan Torus-Modified (STOR-M) tokamak [Phys. Fluids B 4, 3277 (1992)], application of a negative bias results in large negativ e radial electric field, E(r), at the plasma edge, reduced plasma toro idal rotation velocity, and a large poloidal rotation in the electron diamagnetic drift direction. Conversely, a positive bias leads to a re latively small negative E(r) at the plasma edge, a positive E(r) in th e scrape-off layer, increased toroidal rotation, and an increased polo idal rotation speed in the ion diamagnetic drift direction. Increases in edge plasma density and steepening of its radial profile have also been observed for both polarities.