Multi-Chord Upgrade for UV Spectroscopic Profile Measurements in the DIII-D Lower Divertor*

The recently commissioned High-Resolution Ultraviolet Spectrometer (HRUVS) is being upgraded from a single sightline to multiple viewing chords to quantify the spatial distribution of fuel and impurity emission of both low- and high- Z ions and neutrals. The upgrade will additionally provide simultaneous spectroscopic profiles from the HRUVS & Multichord Divertor Spectrometer (MDS), thereby reducing repeat experimental shots needed for coverage of multiple wavelengths. Measured profiles of ion emission will allow for comparisons with predictions from boundary codes such as SOLPS-ITER, UEDGE, and OEDGE. The HRUVS is optimized for 200 to 400 nm wavelengths with high-throughput and ~0.16 Å resolution at 250 nm to investigate high-Z erosion and re-deposition physics. A new design is underway to improve the utilization of the 150R+2 viewport on DIII-D by increasing the clear aperture of the window while also improving the robustness and adjustability of the existing collection optics for the MDS and DiMES TV. The new HRUVS view at 150R+2 will provide ~12 sightlines of the lower divertor with a spatial resolution of ~1 cm. The temporal resolution will depend on individual spectral line intensities and plasma conditions but 10 to 100 ms is anticipated for most lines.