Establishment of strong velocity shear and plasma density profile modification with associated low frequency fluctuations

Strong shear of azimuthal plasma rotation velocity and a large density prof ile modification from a hollow to peaked profiles were successfully obtaine d in a cylindrical magnetized plasma, using voltage biased electrodes. The shear region and density profiles could be finely controlled by changing th e voltage biased position as well as by the magnetic field configurations. A low frequency (<4 kHz) density oscillation was identified as a drift wave type: propagation in the electron diamagnetic direction with a rigid rotat ion (Mach number M similar to -1 at the edge), opposite to the direction of the edge plasma rotation with M similar to1. (C) 2001 American Institute o f Physics.