RESISTIVE EFFECT ON ION FISHBONE MODE IN TOKAMAK PLASMA

A consistent theoretical description of the resistive internal mode is presented to discuss the effect of resistivity on fishbone mode for different parameter regimes of bulk and hot components. We find that the ideal fishbone mode theory ceases to be correct for the low frequency fishbone branch, the so-called ion fishbone mode, which has a real frequency very dose to \omega_*i (the diamagnetic frequency) in marginal state. The stability domain analysis in (\hat\beta_h, \hat\gamma_mhd) space based on the resistive dispersion relation shows that the transition between the stable and unstable regions is much more complicated than predicted by the ideal limit theory. Another salient feature of the resistive fishbone mode is the existence of a weakly unstable regime. For high frequency fishbone with \omega≈\omega_dm (the toroidal precession frequency of the hot ions), resistivity has negligible effect and the ideal theory is correct.