Characterizing the role of neutrals on edge and divertor conditions
2025 Research Campaign, Thrust: High Opacity and Density Operation
Purpose of Experiment
This experiment comprises a multi-institutional study to characterize the connection between neutral particles and critical operational parameters for future reactors, such as plasma fueling, the transition to high confinement mode (H-mode), and maintaining divertor heat loads within material limits. Future devices will require pellets for efficient core plasma fueling. These experiments will leverage recent upgrades to the DIII-D pellet injection system to evaluate the compatibility of such core transient fueling whilst stably maintaining low heat loads at the machine walls. Recent upgrades to the neutral diagnostic capabilities at DIII-D allow for extensive measurements of fueling sources via ionization. These measurements are key for validating edge plasma transport codes: a crucial step in the extrapolation of current experiments to future machines like ITER. Such measurements will also be used to enhance our understanding of the transition to H-mode – necessary for leveraging high performance core plasmas – and of asymmetries in ionization source and drift flows – necessary for optimizing divertor conditions.