Open questions for NT divertor design: field direction, closure and pumping

2025 Research Campaign, Negative Triangularity

Purpose of Experiment

A new Negative Triangularity (NT) divertor is included in the DIII-D 5 year plan for installation in 2026. Its design needs to be optimized via shaping, closure and pumping to access detachment at lower densities, limit confinement degradation and provide particle/impurity control. DIII-D can provide data for edge fluid model validation in NT scenarios, needed for extrapolation towards future devices. This experiment will provide information for the optimization of the planned NT divertor and aims to investigate the optimal field direction for core-edge integration in NT discharges, verifying the feasibility of deep detached conditions in RevBT compatibly with a NT edge and trying to access detachment at reduced upstream densities via impurity radiation.