Low frequency fishbone mode induced by circulating particles in spherical tori

It is found that high beta in low-aspect-ratio tori tends to stabilize the fishbone instability in a plasma with energetic circulating ions. The stabi lization results from enhancement of the toroidal drift motion by large Sha franov shift, which makes it difficult to reconcile the condition of consid erable energy exchange between the ions and the internal kink perturbation with the condition of the resonant wave-particle interaction. (C) 2001 Amer ican Institute of Physics.