Influence of particle trapping on the propagation of ion cyclotron waves

The influence of particle trapping on the nonlinear dynamics of ion cyclotron waves is investigated. It is shown that in the case when the frequency of externally applied electromagnetic waves is close to that of the ion cyclotron waves, the nonlinear coupling between the ion cyclotron waves and the resulting longitudinal perturbations is mainly caused by the pondermotive potential of ions. Due to the trapping of particles, the characteristics of the propagation of the stationary ion cyclotron waves, as well as the condition for their existence, change. Under some circumstances there is no possibility for their propagation. Depending on the amplitude, oscillatory and localized shapes are possible. Trapping of particles makes the characteristic length of modulation larger than the case when it is neglected. (C) 1999 American Institute of Physics. [S1070-664X(99)00405-X].