Nonlinear ion-acoustic waves in e–p–i plasmas with (r, q) distributed electrons and positrons

The influence of the low energy part of the velocity distribution on the propagation characteristics of the nonlinear ion-acoustic waves is investigated in this study by employing the double spectral index (r, q) distribution function. We present an ample study to ascertain how the formation of compressive and rarefactive ion-acoustic solitary structures is influenced by the low energy particles in the distribution profile. We found that only compressive structures are formed for flat top distribution; however, both compressive and rarefactive structures are admissible for spiky distribution. The effect of spectral indices r and q on the formation of solitary structures is explored in detail, and a brief comparison with the Maxwellian and kappa distribution is also given. The present study is imperative in understanding the role of flat top or spiky distributions in plasmas, where positrons are present, and simultaneous observations of such distributions.