Demonstration of Fusion Pilot Plant Physics in SPARC

The SPARC tokamak is designed to demonstrate key areas of tokamak physics necessary to design the ARC fusion power plant, and in doing so achieves the Phase 1A goals of a Fusion Pilot Plant as defined in the Bringing Fusion to the U.S. Grid National Academies report [https://doi.org/10.17226/25991]. While early SPARC operations will focus on achieving the Phase 1A Pilot Plant goal of Q>1, later campaigns transition to generating key data to design ARC. High power deuterium operations will extend databases in H-mode confinement, power thresholds, heat flux width, and ELM behavior to high magnetic field (B₀ = 12.2T) in a compact (R₀ = 1.85m), high density (〈n_e〉≈ 3x10²⁰ m^-3) tokamak. These campaigns will explore non-ELMing high-confinement regimes such as I-mode (likely accessible given SPARC's field) and possibly others. Fueling at high edge opacity, impurities with RF heating, and disruption prediction and control in SPARC also inform ARC design. Critically, SPARC will operate with power-plant equivalent divertor heat fluxes and tungsten PFCs, allowing ARC-equivalent dissipative divertor solutions to be demonstrated at-scale. High power DT plasmas will closely replicate instantaneous conditions expected in the ARC power plant.