Impact of Lithium Injection on the H-mode Pedestal in DIII-D

Lithium injection into ELMy H-mode discharges triggered unusual, up to 350 ms, ELM-free periods (EFPs) during which the pedestal width, $w_{PED}$, increased on a short time scale $\approx$10 ms reaching 2$\times$ the width seen in the ELMy phase. The electron pedestal pressure in EFPs with Li was 2$\times$ that of the ELMy phase and 1.5$\times$ that of similar $e$ was reduced by similar factors in EFPs with $L_i$. Rapid $w_{PED}$ expansion and enhanced particle transport was associate with pedestal localized density fluctuations seen on BES. $w_{PED}$ during EFPs with $L_i$ was $40\%$ larger than predicted by $E_{PED}$1.0 scaling, while $w_{PED}$ in EFPs without $L_i$ agreed with this scaling. EFPs terminated in a large ELM when the peeling-ballooning mode stability limit was reached. Sustainment of large $w_{PED}$, $P_{PED}$ could open a regime of improved energy confinement and high $\beta$ stability.