Effects of non-thermal electron distribution and positron density on solitary waves in electron-positron-ion plasmas

Abstract

A rigorous theoretical investigation has been made of arbitrary amplitude compressive and rarefactive ion acoustic solitary waves in three component plasmas, consisting of ions, positrons and non-thermally distributed electrons. The pseudo-potential approach, which is valid for large amplitude solitary waves and the reductive perturbation technique for small amplitude solitary waves, have been employed. It is shown from both weakly and highly nonlinear analyses that the presence of the fast or non-thermal electrons may allow compressive and rarefactive solitary waves to coexist. It is found that the effect of the positron density changes the minimum value of α (a parameter determining the number of fast electrons present in our model) andM (the Mach number) for which the compressive and rarefactive solitary waves can coexist. The present theory is applicable to analyse arbitrary amplitude ion acoustic waves associated with positrons which may occur in space plasmas.