High resolution multiposition Thomson scattering for the TEXTOR tokamak

In this article, the recently installed high resolution multiposition Thomson scattering (TS) system of the TEXTOR tokamak is presented. Light from a pulsed ruby laser is scattered by the free electrons of the plasma and transmitted by fiber optics to a polychromator for spectral analysis. The Doppler broadened spectrum of the scattered light is analyzed with a Littrow spectrometer, detected with an image intensifier, and recorded with two intensified charge coupled device cameras. Values of the electron temperature (T-e) in the range of 50 eV up to 4 keV can be measured at 450 spatial elements of 2 mm along a chord of 900 mm, with a resolution of 8 mm. The observational error on T-e was found to be <3% at an electron density (n(e)) of 3.5 x 10(19) m(-3) using a laser energy of similar to8 J. These features make-to our knowledge-the multiposition TS system of TEXTOR to be the one with the highest spatial and spectral resolution in the world. In this article the first results of this powerful diagnostic will be presented. (C) 2001 American Institute of Physics.