Atomic calculations, including S/XB values, and comparison to experiment for Si⁺ and W²⁺ erosion diagnostics

New atomic physics calculations have been done to inform development of diagnostics for the spectroscopic monitoring of erosion and re-deposition of wall materials in fusion relevant plasmas. A new ionization calculation for W²⁺, needed to determine W re-deposition rates, has been completed using the R-matrix with pseudostates (RMPS) method. When combined with an existing excitation calculation for W²⁺, this new data generates ionization/photon (S/XB) coefficients, which can be combined with UV spectroscopic measurements to infer time-resolved erosion and re-deposition rates. To transform the collision cross sections from the RMPS calculation into accurate derived coefficients, a new code has been developed that separates each collisional cross section into separate ionization series and extends them to high energies. The techniques used for the W²⁺ calculation have been tested by applying them to a simpler, but still useful, ion: Si⁺. Both calculations have been compared to experimental measurements, which justifies confidence in the derived coefficients, such as the S/XB coefficients. These calculations are benchmarked over a range of plasma conditions by experiments conducted in the DIII-D tokamak using the DiMES removable sample probe and new UV spectroscopy capabilities.