The paper reports the results of a theoretical study of plasma configurations confined by a magnetic field such that the plasma-vacuum interface is characterized by structurally stable field lines. The plasma is modelled by the MHD approximation and the configuration is chosen to represent the Brigham Young University Topolotron. Representative results for numerically computed, diffuse-profile, Grad-Shafranov equilibria are reported. The local instability properties of several equilibria have been studied with respect to ballooning modes. The equilibria studied have marginal beta values in the range of 0.5−2.0%. Finally, computations are summarized which illustrate the destruction of the structurally stable magnetic field by small field errors and it is concluded that structurally stable magnetic surfaces do not exist in real devices.
Method of magnetic analysis for stellarator equilibria