Space- and time-resolved visible-emission spectroscopy of Aditya-tokamak discharges using multi-track spectrometer

A diagnostic system based on a multi-fiber input high resolution spectrograph has been set up on the Aditya tokamak (Bhatt et al 1989 Ind. J. Pure Appl. Phys. 27 710) for utilizing the passive light emission to measure different kinds of plasma flow and to identify the location of emissions of hydrogen and impurities along with their temperatures. Eight simultaneous vertically collimated lines-of-sight from a top port view a poloidal cross-section of the plasma. This arrangement simplifies the analysis of spectra in terms of making the Zeeman splitting easier to account for, since each chord passes through a region of nearly constant toroidal magnetic field (B _T). This paper describes the complete set-up, the wavelength and intensity calibrations performed and the initial results including the impurity emissivity profiles and simultaneous flow measurements in the inboard and outboard regions of the Aditya tokamak.