Density profile peaking inside m/n=2/1 magnetic islands in TEXTOR-94

Abstract

Density profile perturbations due to large rotating m/n = 2/1 magnetic islands have been studied by means of a four channel pulsed radar reflectometer in TEXTOR-94. The time of flight of the microwave pulses was strongly affected by the shallow density gradients over the magnetic islands. A detailed analysis showed the existence of secondary reflection lavers inside the magnetic island, which is an indication of a strong density peaking. This may be explained by assuming that the particle transport is reduced inside the magnetic island.