Development of an advanced magnetic equilibrium model for fusion reactor system codes

Fusion system codes are vital computational tools for the assessment of the key design parameters of a fusion power plant. The main goal is to capture the key physics and technology aspects, pushing the solution to comply with physics and engineering requirements and constraints. Based on that, the magnet system has to be designed to match the requirements on magnetic equilibrium as well as the technological constraints on superconductive coils. A dedicated model was developed to evaluate the coupling effects between the external poloidal field coils (PFCs) and the plasma, described in terms of its magnetic equilibrium configuration. The model first attempts to reproduce a magnetic configuration for a given set of plasma parameters within a target confining region. To achieve such an arrangement, a coil solver calculates the toroidal electrical currents in PFCs. In this paper, the mathematical details of this equilibrium model are presented and the main results referred to magnetic flux, field and coil currents are compared to a reference DEMO scenario calculation.