Evolution of unstable ion acoustic solitons

The evolution of a localized potential perturbation in a plasma of cold, ki netic ions and Boltzmann electrons is investigated computationally. We find that small perturbations evolve into a train of stable ion acoustic solito ns, as predicted by the Korteweg-deVries theory, Large perturbations, howev er, are found to evolve into solitons that exceed the soliton speed limit. Such solitons are unstable and decay by emitting reflected ions bursts and ion acoustic waves.