Multichannel Thomson scattering apparatus.

A Thomson scattering apparatus for measuring the electron temperature and density along a 90-cm diam of the PLT plasma has been built. A wide angle objective images the 3-mm x 900-mm ruby laser beam onto an image dissector which rearranges the 300:1 image to 20:1 forming the input slit of a spectrometer. The stigmatic spectrometer provides twenty wavelength elements of ~70 A each. A microchannel-plate image intensifier optically coupled to a cooled SIT tube provides detection with single frame linearity and 1000:1 dynamic range. Spatial profiles of N(e) and T(e) in the 10(13)-10(14)-cm(-3) range and 0.05-3 keV have an accuracy of 30 [10(13)/N(e) (cm(-3))]((1/2))% per 1.2-cm element.