Access to Edge Transport Barriers and Projections of Pedestal Performance in the SPARC Tokamak

Access to a sufficiently large edge pedestal on the SPARC tokamak will be a key ingredient in the realization of high fusion gain on this compact (R=1.85m, a=0.57m) high field (reference BT=12.2T) device. Following initial investigations of access to H-mode operation and predictions for pedestal pressure in the SPARC Primary Reference Discharge (PRD), projections of I-mode access have been made, with the aim of identifying potential scenarios of high confinement operation free of large edge localized modes (ELMs). Power threshold projections for the I-mode regime are comparable to those for H- mode, and in the highest BT scenarios, potentially less demanding. Initial investigations to map I-mode pedestals from existing devices on SPARC show promise for utilizing the regime to remain away from H-mode and large ELMs.