Modeling dissipative divertor designs for DIII-D with variations in wall baffling and pump location

In the upcoming DIII-D 5-year plan, a deep-baffled dissipative divertor with a long outer poloidal leg length of ~50 cm is planned, with the aim to provide data to constrain models for predicting radiation and detachment processes in a fusion pilot plant. The plasma boundary codes SOLPS-ITER and UEDGE are used to evaluate designs of this dissipative divertor for plasmas with up to 25 MW of heating power, focusing on the effects of baffle geometry (including particle drifts) and pump location on the divertor solution. Cross-field transport coefficients are tuned to match the heat flux width from the ITPA scaling and the pedestal shape of a recent 16 MW DIII-D plasma. Increasing divertor baffling in the scrape-off-layer (SOL) better confines neutrals in the divertor, but the overall effect is small for detached solutions, with just 5 to 10% electron density increase in the divertor far-SOL when the baffling is approximately conformal to SOL flux surfaces. Increased baffling in the private flux region (PRF) restricts neutrals sourced at the inner divertor from reaching the outer divertor leg through the PFR, and compresses neutrals at the X-point. Moving the pump location upstream from the divertor target reduces pump throughput for a given upstream separatrix density, but increases the local density near the target and thus dissipation, highlighting a robust trade-off between the ability to exhaust particles and dissipate power.