Ion-acoustic waves in magnetised plasma with nonthermal electrons and positrons

Zakharov-Kuznetsov (ZK) equation for ion-acoustic waves (IAWs) is derived using the reductive perturbation method (RPM) in magnetised plasma consisting of ions, positrons and nonthermal electrons in small but finite amplitude limit. Propagation characteristics of ion-acoustic solitary waves (IASWs) in three-dimensional space are analysed to determine their region of existence. Investigations reveal that ion-acoustic solitary pulses (IASPs) may exist in such plasmas and presence of nonthermal electrons significantly affects the amplitude and width of solitary pulses. Dependence of velocity, amplitude and width of solitary pulses on plasma parameters are presented graphically. The amplitude of soliton increases with increase in ion temperature ratio (sigma) and positron concentration (alpha). However, it decreases with increase in nonthermal electron parameter (beta) keeping other plasma parameters constant. Width of the soliton increases with increase in beta, sigma and alpha. Phase velocity of ion-acoustic wave (lambda) increases with increase in nonthermal beta and sigma. In our analysis, we found that magnetisation of plasma affect the width of the soliton but not the amplitude.