Optimization design for plasma configuration at the CFETR

Abstract Equilibrium is essential in the design of the Chinese Fusion Engineering Test Reactor (CFETR). It is based on the principle underlying various physical and engineering issues, such as vertical instability, core plasma physics, divertor physics and design, etc. Built on the 0-D parameters with elongation κ∼2.0 using the equilibrium code TEQ, series of equilibria with different lower triangularity (range of 0.3–0.8) were constructed. Through iterations with the divertor and blanket structures, we optimized the plasma shape, including, in particular, the position of the X-point, hence obtaining the first acceptable single-null plasma with δ = 0.418. This optimal ITER-like equilibrium has in turn served as the starting point for various other design works. Besides the standard divertor configuration, the quasi-snowflake-plus (QSF+) divertor configurations with different total plasma currents have also been produced, which aimed at controlling excessive heat flux load on the divertor target. The results indicate that the poloidal field (PF) coil system has the capacity to sustain the shape of the QSF+; however, the PF coil system will continue to be optimized with particular attention of the divertor coil.