Nonlinear propagation of partially coherent dispersive Alfven waves

The effects of partial coherence on the propagation of dispersive Alfven waves in a magnetoplasma are investigated. In particular, nonlinear interactions between dispersive Alfven waves and ion-acoustic perturbations are considered by means of a Wigner formalism. A set of governing equations consisting of a kinetic equation for dispersive Alfven waves coupled nonlinearly to a ponderomotive force driven ion-acoustic wave equation is obtained. The governing nonlinear equations are used to derive a nonlinear dispersion relation that is appropriate for investigating the modulational instability of broadband Alfven wavepackets. The spectral broadening of the Alfven waves gives rise to new regimes for the growth rate of the modulational instability.