Nonlinear Magnetosonic Fast and Slow Waves in Finite β Plasmas and Associated Resonant Ion Acceleration

Abstract

Korteweg-de Vries equation that is applicable both to magnetosonic fast and slow waves is derived from a two-fluid model with finite ion and electron pressures. For all propagation angles with the external magnetic field, the slow wave has the positive soliton. The fast wave has the positive soliton in quasi-perpendicular propagation and the negaive soliton for the angle below the critical angle; finite β effects lead to the broardening of the region of the positive soliton. The theory is applied to the v p × B acceleration by the nonlinear fast and slow waves. It is found that the slow waves can strongly accelerate the ions in high β plasmas, and that the finite β effect enhances the acceleration in the fast wave.