Spectroscopic Measurements of Impurity Spectra on the EAST Tokamak

Ultraviolet (UV) and visible impurity spectra (200-750nm) are commonly used to study plasma and wall interactions in magnetic fusion plasmas. Two optical multi-channel analysis (OMA) systems have been installed for the UV-visible spectrum measurement on EAST. These two OMA systems are both equipped with the Czerny-Turner (C-T) type spectrometer. The upper vacuum vessel and inner divertor baffle can be viewed simultaneously through two optical lenses. The OMA1 system is mainly used for multi-impurity lines radiation measurement. A 280nm wavelength range can be covered by a 300mm focal length spectrometer equipped with a 300g/mm grating. The D?/H? line shapes can be resolved by the OMA2 system. The focal length is 750 mm. The spectral resolution can be up to 0.01nm using a 1800g/mm grating. The impurity behaviour and hydrogen ratio evolution after boroniztion, lithiation, and siliconization are compared. Lithiation has shown beneficial effects on the reduction of edge recycling and low Z impurity (C、O) influx. The impurity expelling effect of the divertor configuration is also briefly discussed through multi-channels observation of OMA1 system.