Observations of visible argon line emissions and its spatial profile from Aditya-U tokamak plasma

The spectroscopic studies of medium and high Z impurities have been the subject of interest in fusion research due to their role in mitigating plasma disruption and reducing heat load on the plasma facing components. Line emissions from these impurities provide the rotation velocity and ion temperature measurements along with the understanding of the overall impurity behavior in plasma. In the Aditya-U tokamak, the spatially resolved Ar II line emissions have been observed using a high resolution multi-track spectroscopic diagnostic consisting of a 1 m Czerny-Turner spectrometer coupled with a charge coupled device (CCD) detector using seven lines of sight viewing plasma tangentially along the toroidal direction. The spatially resolved Ar II lines at 458.96 nm have been observed. The singly ionized Ar emission peaks at the radial location of ρ = 0.8 of the plasma having a minor radius of 25 cm. Moreover, a 0.5 m UV-visible spectrometer coupled with a CCD detector and having a line of sight passing through the plasma midplane from the radial port was used to record visible Ar survey spectra within the 670-810 nm wavelength range, and all these lines have been identified for further analysis.