Nonlinear periodic ion-acoustic waves in nonthermal plasmas

Abstract

A Sagdeev pseudopotential analysis is developed for the propagation of nonlinear periodic ion-acoustic waves in a plasma comprising cold fluid ions and various models of nonthermal electron descriptions. In plasma nonlinear wave studies, whether addressing solitary or periodic modes, the more common nonthermal distributions are the Cairns, kappa, and Tsallis models. A mathematically and physically consistent description incorporates three evident properties: there is conservation per cycle of ion and electron densities in addition to ion flux, the solutions reduce for very small amplitudes to linear waves, and the nonlinear periodic structures are generated by a perturbation of the undisturbed equilibrium. After establishing the corresponding general analytical methodology, a numerical analysis is given, with illustrative graphs, for the nonthermal Cairns, superthermal kappa, and nonextensive Tsallis distributions.