Stability of n=1 kink modes in bean-shaped tokamaks

Numerical studies show that by indenting the small-major-radius side of conventional finite-aspect-ratio tokamaks, significant improvements to the stability of pressure-driven ideal magnetohydrodynamics modes can be achieved. The internal n = 1 kink mode can be stabilized completely with quite modest indentation. In the presence of a nearby conducting wall, kink-ballooning mode stability is also improved, and accessibility to a second stable region at high plasma ..beta.. is possible.