Investigation of high-beta tokamak stability with the program HBT

The numerical program HBT has been employed to study global and local stability of high-beta axisymmetric toroidal plasmas with various cross-sections. The stability results of different classes of equilibria for a circular plasma show that high stable betas (<β>/epsilon=0.082) can be found when negative toroidal current densities are admitted in a small region on the inside of the torus. Shaping the cross-section makes further improvements possible. The optimum betas found are in qualitative agreement with Troyon's scaling law. (author)