Investigations on density and temperature asymmetries due to drift motions in the boundary layer of TEXTOR-94

Abstract Electron densities and temperatures in the plasma edge have been measured by means of the helium beam diagnostic. Furthermore, the charge exchange signal driven by the thermal helium beam atoms has been used to measure the poloidal velocities of C6+ ions. Asymmetries in the radial profiles of the edge parameters have been found. For further analysis of the physical mechanisms, calculations have been performed with the 2D boundary layer code TECXY. Experimental and modeled results are compared. The influence of the line averaged electron density and the heating power on the electron density and temperature ratios between low field side (LFS) and high field side (HFS) inside the scrape off layer (SOL) is shown. Not only drift motions but also other effects such as recycling at the limiters have an important influence on the spatial structure of the plasma parameters in the SOL.