A SPATIALLY SCANNING VACUUM-ULTRAVIOLET AND VISIBLE RANGE SPECTROMETER FOR SPECTROSCOPY OF TOKAMAK PLASMAS IN ASDEX-UPGRADE

A spatially scanning, combined vacuum-ultraviolet (VUV) and visible ra nge spectrometer system for the spectroscopy of tokamak plasmas in the ASDEX-Upgrade experiment is described. This system is designed to all ow flexible observation of about 2/3 of the boundary plasma using VUV (30-200 nm) and visible range spectrometers viewing along a common lin e of sight which can be scanned during the plasma discharge by means o f a rotatable mirror. From successive spectra recorded using intensifi ed, multichannel photodiode detectors and the recorded position data, spatial profiles of the plasma emission can be reconstructed. Because radiation losses from the boundary plasma can largely be attributed to line emission in the VUV spectral region, this instrument finds appli cation in quantitative studies of radiation loss processes as well as to studies of impurity production and transport. Simultaneous observat ion in the visible spectral range facilitates an in situ absolute cali bration of the VUV instrument by means of the ''branching-ratios'' tec hnique. (C) 1995 American Institute of Physics.