Poloidal field system and advanced divertor equilibrium configuration design of the EHL-2 spherical torus

The EHL-2 (ENN He-Long 2) spherical torus (ST) project focuses on advancing spherical torus technology to address the unique challenges of p-¹¹B fusion, which demands significantly higher ion temperature and heat flux to the divertor plate compared to traditional deuterium-tritium fusion. With a major radius of 1.05 m and a plasma current of 3 MA, the project aims to evaluate and optimize advanced divertor configurations, specifically the Super-X and X-point target (XPT) divertors. The design incorporates an up-down double-null configuration featuring a conventional inner divertor and an XPT outer divertor to effectively reduce the heat flux. The poloidal field (PF) coil system is meticulously optimized to balance engineering constraints with the flexibility in equilibrium configurations. This design is expected to provide a reference equilibrium configuration for other physics design issues and offer critical insight into heat load management.