Influence of trapped electrons on ion-acoustic solitons in plasmas with superthermal electrons

A model for describing the physics of both superthermal and trapped electrons is presented. This is important because most of the space and some of the laboratory plasmas contain a population of superthermal particles. Due to the superthermal electrons, a high-energy tail appears in the electron distribution function that is conveniently modeled by the kappa distribution function. The distribution function of trapped particles is modeled based on the simulation result of the Vlasov-Poisson system of equations. An analytical expression for the electron density is obtained. The ion-acoustic solitons are studied in this framework. (c) 2007 American Institute of Physics.