Poloidal plasma rotation and its effect on fluctuations in a toroidal plasma

An experimental study on poloidal plasma rotation induced by electrode biasing and its effect on fluctuations is carried out in a purely toroidal plasma having no poloidal magnetic field. Poloidal plasma rotation and, concomitantly, significant reduction in the fluctuation level are observed. The radial profiles of poloidal flows and fluctuations are measured and compared. The dependence of the poloidal plasma rotation on the bias voltage and the toroidal magnetic field is presented. It is found that the large poloidal plasma rotation gives rise to a transition of the plasma state from a turbulent to a coherent mode