NON-LINEAR STABILITY OF ENVELOPE SOLITONS

The instability of plane envelope Langmuir solitons subject to transverse perturbations is reconsidered for the cubic nonlinear Schrödinger equation as well as the coupled set of high- and low-frequency equations in the case of nonadiabatic ion response. The nonlinear investigation demonstrates instability with a cutoff in all cases and predicts a drastic lowering of the instability growth rates when nonadiabatic ion motion is allowed for. Our analytical results agree with recent numerical computations. © 1978 The American Physical Society.