An ultraviolet-visible-near infrared overview spectroscopy for divertor plasma diagnosis on Wendelstein 7-X

A new ultraviolet-visible-near infrared (UV-VIS-NIR) overview spectroscopy has been developed for routinely monitoring divertor recycling, intrinsic and extrinsic impurity fluxes on Wendelstein 7-X (W7-X). The overview spectroscopy is part of a large integrated system which allows several diagnostic systems to share the same field of view through an endoscope. During the first divertor operation phase on W7-X, a temporary view port was setup for the overview spectroscopy in order to investigate the divertor plasmas and provide reference data for the commissioning of the whole integrated endoscope system. The overview spectroscopy uses a 5-channel spectrometer to cover the wavelength range 300-1100 nm. The reciprocal linear dispersion of the spectrometer are in the range of 0.04-0.19 nm/pixel. The spatial coverage of the system is 10 cm in the vertical direction and 20 cm in the toroidal direction. The first full spectral survey identified H, He, C, O, Fe, Ne, N and Ar lines. The temporal evolutions of hyd...