Parametric study of kinetic Alfvén solitons in a two electron temperature plasma

The nonlinear regime of the kinetic Alfvén wave is studied in a collisionless low-β plasma that is composed of a cold ion population and of two electron populations. In the one electron population plasma, it is known that solitary kinetic Alfvén waves (SKAW) propagate either at the Alfvén velocity υ_A or at the ion-acoustic velocity c_s. In this latter case, only plasma compressions exist. In the two electron population plasma, rarefactions, as well as compressions, may exist at this velocity. Furthermore, when the electron-acoustic mode exists and when υ_A>υ_ea (υ_ea is the electron-acoustic velocity), the inertia of the cold electron component allows for the existence of compressive SKAW which propagate with a velocity lying in a limited interval above υ_ea When υ_A<υ_ea, these solitons are rarefactive and continuously evolve from classical SKAW moving at υ_A to electron-acoustic-like SKAW moving at υ_ea. The possibility of applying these results to some astrophysical plasma observations is investigated.