Planned modification of DIII-D upper divertor to produce more reactor relevant H-mode pedestal conditions

DIII-D plans to modify the upper divertor baffle design to increase plasma elongation and triangularity while maintaining density control to expand access to high pedestal pressure. Good overall performance in H-mode based reactors requires high H-mode pedestal pressure, p^PED, at high density, n_e^PED. These pedestals will be in a regime of high opacity to neutrals entering from the scrape off layer but low collisionality. These conditions are difficult to achieve simultaneously in present experiments but are expected to impact achievable p^PED through effects on pedestal transport and stability. These conditions can be more closely approached in DIII-D at high plasma current in high triangularity, high elongation, large minor radius discharges in the super-H-mode regime where p^PED increases with n_e^PED. Entering and maintaining super-H-mode requires control of n_e^PED as a function of temperature during the ramp-up to avoid reaching the ballooning mode limit where p^PED is reduced and decreases with n_e^PED. The density control requirement creates a tension between the achievable elongation and triangularity, the requirements to accommodate a range of scrape off layer widths, and sufficient divertor leg length to maintain midplane to divertor temperature difference. A proposed modular divertor design to maximize flexibility in these competing parameters will be presented.