Rapid optimization scheme for Poloidal Field design of tokamak with divertor configuration

The Poloidal Field (PF) coil system in a tokamak must be optimized, taking into account the desired flexibility in plasma equilibria, and practical constraints on the number of coils, their locations and dimensions. Such optimization requires the generation of a large number of magetohydrodynamics (MHD) equilibria spanning the desired equilibrium space. Given the large parameter space, it is necessary to use a fast method for determining the PF coil system required for a given plasma equilibrium. In this work, an inverse Grad–Shafranov solver is coupled with a PF coil current optimizer which incorporates various design constraints. The method can handle shaped tokamak plasma equilibria with a divertor configuration. This method is found to be considerably faster than conventional free-boundary codes, and the calculated PF coil currents are in reasonable agreement with those from free-boundary solutions. This method has been applied to PF optimization of SST-1 for maximizing the operational envelope.