Commissioning of a UV Spectrometer on DIII-D for Tungsten Erosion & Re-deposition Measurements

A new high-resolution and high-throughput spectrometer optimized for ultraviolet wavelengths is being installed on DIII-D to resolve the most promising W line radiation arising from erosion during W sourcing experiments in the divertor. Spectral surveys between 200 and 400 nm have identified over 60 neutral and singly ionized W emission lines. These lines, combined with atomic predictions, allow for the determination of net erosion and re-deposition rates of W via the ionizations/photon (S/XB) method. Simultaneously monitoring multiple W emission lines is required to determine the W metastable level populations in order to accurately characterize erosion and re-deposition rates. The new UV spectrometer has a maximum resolving power of 0.16 Å at 250 nm with better than 1 kHz temporal resolution. Initial measurement calibrations will be presented with the spectrometer located inside of a shield box on the top of the tokamak and fiber-coupled to collection optics.