Limitations of Two-Dimensional Model Equations for Ion-Acoustic Waves

Abstract
It is shown that plane ion-acoustic solitons are unstable in magnetized plasmas if the magnetic field is greater than a critical value which roughly corresponds to the condition that the soliton width equals the ion gyroradius. On the other hand, ion-acoustic solitons are stable if their amplitudes exceed a corresponding magnetic-field—dependent threshold. Limitations of previous models are discussed.