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 × 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 Ne and Te in the 1013–1014-cm−3 range and 0.05–3 keV have an accuracy of 30 [1013/Ne (cm−3)]1/2% per 1.2-cm element.