Review of the experimental verification on the enhancement of edge turbulence by biasing

Well-known the theoretical studies deal with two mechanisms of turbulence suppression by the shear of the poloidal rotation velocity and due to the plasma shift to inner board over a time shorter than the inverse increment. In paper the possibility of increasing the level of edge turbulence by a limiter current was pointed out. The enhancement of the turbulence is possible due to the variation of the sheath potential at the plasma-surface boundary provided that the positive current flows to the surface. In this brief review a new experimental results which were obtained by biasing in different tokamaks are discussed. The earlier observations of turbulence changing with biasing were considered. For instance, an increase of the flow potential fluctuations in the SOL up to eφ/Te>3 was observed in TEXTOR. (orig.)