Reflectometry measurements during operation of the dynamic ergodic divertor at TEXTOR

The O-mode correlation reflectometer at TEXTOR is used for the investigation of the propagation and the properties of the turbulence at the plasma edge. The multi-horn antenna set-up allows the investigation of the correlation properties of the turbulence and its rotation. Turbulence and plasma rotation for different plasma conditions are found to be in agreement and based on this comparison the radial electric field is estimated. In addition the density fluctuation level is estimated from the standard deviation of the phase of the reflected signal. The influence of a magnetic perturbation field, generated by the dynamic ergodic divertor (DED), on the turbulence and transport properties is studied and compared with plasmas without such a field perturbation. The strength and radial range of the perturbation field can be widely varied. Together with tangential neutral beam injection in co- and counter-current directions, the turbulent transport is investigated. The combination of neutral beam injection and the DED enables the modification of the plasma rotation profile. It can lead either to the generation of a locked mode or the formation of a transport barrier.