Update on a Scanning, 2-Dimensional Divertor Thomson Scattering System on DIII-D

We present recent upgrades to enable scanning, 2-dimensional divertor Thomson scattering (DTS-2D) measurements of T_e and n_e in DIII-D. This system expands the current capabilities of the existing lower divertor floor measurement location by introducing 7 additional laser beam paths in the poloidal plane, covering R=954 mm to R=1335 mm at 12 vertical positions from Z=-1.35 m to Z=-1.13 m. The system will redirect a ~1J, 50Hz, Nd:YAG laser pulse to a new beam path within 20 ms, continuously scanning through all 8 positions each 160ms period during a plasma shot. Up to 12 measurements are available at each beam position by dynamically refocusing the collection fiber array using a high-speed linear stage. The 8 beam paths are accessed by redirecting the laser using an ex-vessel, fast-steering mirror to 1 of 8 in-vessel prisms mounted underneath the tiles. A fixed, in-vessel mirror with a centered hole allows the laser to pass through, retaining measurements above the divertor shelf. This work focuses on system design, specifications, and initial results from the recent installation. Initial measurement work will be to investigate the differences between 2D maps made from sweeping a diverted plasma across a single Thomson scattering beam path and a stationary plasma measured with DTS-2D.