Impact of the Isotope Mass on Divertor Detachment and Pedestal Fueling in DIII-D

Experiments and SOLPS-ITER modeling have been conducted to understand the effect of the isotope mass on the pedestal and divertor region. Comparable discharges were produced by matching the line averaged core density of Hydrogen (H) shots to Deuterium (D) references in both H-mode and L-mode. Access to H-Mode required higher injected power in H and resulted in a lower normalized beta compared to the D references. The pressure pedestal degradation is more severe at higher gas puffing in H versus D despite the higher pedestal electron densities and density gradients in H. Pedestal stability analysis shows reduced peeling-ballooning stability in H with both the H and D discharges being ballooning limited. SOLPS-ITER modeling with full drifts and matched upstream profiles predicts H detaches at a higher upstream density. The particle source from neutral ionization inside the LCFS is also higher in the H simulations than in the D simulations. Direct comparisons are made between LLAMA spectrometer brightness measurements and that from a synthetic Ly-α diagnostic in the simulations. The inferred ionization and neutral density profile from LLAMA will be used to assess the models accuracy in predicting these parameters.