Torsatron equilibrium and stability studies

Equilibrium and stability results are presented for the Advanced Toroidal Facility (ATF) device. The results of three-dimensional equilibrium calculations and free-boundary average method calculations are shown to be in good agreement with previous fixed-boundary average method results. These favourable comparisons serve as a valuable validation of the simple and computationally efficient fixed-boundary average method. Stability calculations for the free-boundary average method equilibria are also in good agreement with fixed-boundary calculations, showing instability only when the plasma is shifted inwards with an applied vertical field.