A New Tool Gseq-Frc For Two-Dimensional Field-Reversed Configuration Equilibrium

A new tool (GSEQ-FRC) is developed for solving two-dimensional equilibrium of the field-reversed configuration (FRC) based on fixed boundary and free boundary conditions that includes external coils. Benefiting from the two-parameter modified rigid rotor radial equilibrium model and the numerical approaches presented (Ma et al 2021 Nucl. Fusion 61 036046) in this work, the GSEQ-FRC code is used to study the equilibrium properties of FRC quantitatively and will be used for fast FRC equilibrium reconstruction. In GSEQ-FRC, the FRC equilibrium is determined by two parameters, i.e. the ratio between thermal pressure and magnetic pressure at the separatrix beta ( s ), and the normalized scrape of layer width delta ( s ). Examples with fixed and free boundary conditions are given to demonstrate the capability of GSEQ-FRC for equilibrium calculations. This new tool is used to quantitatively study the factors affecting the shape of the FRC separatrix, which reveals how the FRC changes from racetrack-like to ellipse-like.