Measurements with the fast repetitive multi-pulse Edge Thomson scattering system on TEXTOR

A fast repetitive multi-pulse Edge Thomson Scattering system is in operation since March 2006 and provides a sophisticated tool for the study of transport processes in the edge region of the tokamak TEXTOR. The specially designed viewing optics enables the study of the dynamics of fast plasma phenomena with high spatial resolution at the plasma edge. Various measurements under different plasma conditions were performed where the influence of resonant magnetic perturbations generated by the Dynamic Ergodic Divertor on fast electron transport in the edge region was a point of emphasis. The electron density and temperature profiles obtained will be compared with other edge diagnostics based on different measuring principles. The system utilizes a ruby laser delivering bursts of 15 pulses each with a pulse energy of about 15 J. The TEXTOR plasma itself is inside the laser cavity where the double-pass system allows high laser energies of each laser pulse through the plasma. The new edge system (170 mm) has 98 spatial channels of 1.7 mm each. The lower detection limit of the edge system for Te is observed to be 30 eV