Nonlinear ion-acoustic waves supported by an ion beam

Abstract

It is shown that in a plasma composed by electrons, a proton core, and a proton beam propagating along an external magnetic field, finite amplitude left-hand polarized waves propagating backward relative to the beam direction can trigger nonlinear ion-acoustic waves supported by the beam. A detailed study of such instabilities is carried out. The instability bounds are such that if there are large amplitude left-hand polarized waves propagating toward the Sun, nonlinear ion-acoustic waves supported by the beam should exist in high-speed solar wind streams.