GITR Simulations of Ion Impacts on the DIII-D DiMES Divertor Sample Targets

GITR is a Monte Carlo code that models the gross and net erosion of PFCs, and the re-distribution of eroded impurities. [1] We used GITR to evaluate the effect of incident IADs at the divertor surface in specifically designed DiMES measurements on DIII-D.

 

Experiments using DiMES exposed 30×30×2-4 µm Si trenches adjacent to a surface coated with Al to L-mode D discharges for 10 seconds. The resulting Al and C concentrations deposited in the trench were measured by EDS [2]. A Monte Carlo micro-patterning and roughness (MPR) code [3] computed erosion profiles strongly resembling experimental trends [2]. More rigorous simulations are needed from GITR to consider particle transport and Al erosion to validate initial estimates that the incident angle caused the deposition patterns, instead of the mass or charge state ratio between D and Al. GITR was extended to include reliable Al transport and material wall interaction coefficients, and a validation effort is ongoing to model this experiment. Full-scale modeling allows for the identification of the upstream Al velocity distributions able to deposit in the trench. A comparison between the GITR results, MPR results, and experimental results from the DiMES measurements will be presented, including a systematic variation of the IADs.