THEORY OF RESONANCE INFLUENCE OF SAWTOOTH CRASHES ON IONS WITH LARGE ORBIT WIDTH

The role of resonances in the sawtooth-crash-induced redistribution of fast ions is investigated. In particular, the conditions of wave-part icle resonant interaction in the presence of the equilibrium electric field and the mode rotation are obtained, and effects of sawteeth on t he resonant particles with arbitrary width of nonperturbed orbits are studied. It is found that resonances play the dominant role in the tra nsport of ions having sufficiently high energy. It is shown that the r esonance regions may overlap, in which case the resonant particles may constitute the main fraction of the fast ion population in the sawtoo th mixing region. The behavior of the resonant particles is studied bo th by constructing a Poincare map and analytically, by means of the ad iabatic invariant derived in this paper and calculation of the charact eristic frequencies of the particle motion. (C) 1998 American Institut e of Physics.