Dynamics of broadband dispersive Alfvén waves

The properties of amplitude modulated broadband Alfvén waves are investigated. In particular, the dynamics of circularly polarized dispersive Alfvén waves, governed by a derivative nonlinear Schrödinger equation, is analyzed using the Wigner formalism. The modulational instability of random phase dispersive pump Alfvén waves is investigated, and it is shown that the spectral broadening gives rise to a new mode structure.