Analysis of GITR simulated W erosion and comparison with optical emission spectroscopy in the DIII-D SAS-VW divertor as a step toward validation

Preliminary impurity transport modeling with a favorable Bt direction (USN with reverse Bt) indicates that the majority of eroded W in the DIII-D SAS-VW divertor is re-deposited within the divertor, closer to the slot vertex. Higher net erosion near the outboard slot entrance may contribute to elevated W leakage into the core. Understanding impurity transport is critical for minimizing net erosion of PFCs in a tokamak, and for minimizing core contamination by impurities. Monte Carlo transport analyses using GITR offers insight to the dominance of Lorentz, frictional, and temperature gradient forces and drifts on local transport in the SAS-VW and their effects on prompt redeposition patterns.

GITR simulations of W transport in the SAS-VW, compared with experimental data, provide a validation opportunity for GITR predictions in a tokamak. The gross erosion rate of W at 3 locations along the SAS-VW was experimentally measured using a multi-chordal divertor spectrometer and a filterscope to quantify characteristic W-I photon emission. The S/XB method is used to calculate the experimental gross erosion flux for direct comparison to GITR results.