Plasma rotation measurement using UV and visible spectroscopy on Aditya-U tokamak

A high resolution spectroscopic diagnostic for the measurement of the spatial profile of toroidal rotation velocity (v_t) and temperature (T_i) of carbon ions has been developed and implemented on the Aditya-U tokamak. The diagnostic consists of a high resolution 1 m (f/8.7) spectrometer having an 1800 grooves/mm grating coupled with a charged couple device. The setup allows measurements from 5 toroidal lines-of-sights passing through different minor radii in the horizontal mid-plane of the Aditya-U tokamak. The carbon line emissions at 529 nm in visible and 229.6 and 227.09 nm in the ultra violet spectral range are recorded using the setup. Initial results show that typical Aditya-U plasmas have a maximum carbon ion temperature (T_i) of ∼120 eV and a rotation velocity (v_t) of ∼-14 km/s in the counter plasma-current direction.