Ion acoustic solitary waves in an electron–ion–positron plasma

Large amplitude ion-acoustic solitary waves have been theoretically studied in a non-collisional plasma consisting of warm positive ions, positrons and isothermal electrons using pseudo-potential (effective potential) method. The expressions of phase velocities of slow- and fast- modes of the wave have been derived and graphically analyzed. The critical values of densities of the positrons and the ions, Mach number and positron temperature for the excitation of ion-acoustic solitary wave have also been obtained. The solutions of the first-order and next higher order solitary waves have been obtained and the profiles of the solitary waves have been drawn taking different values of the plasma parameters. It has been observed that both compressive and rarefactive solitary waves are being excited in presence of positrons in the plasma. The variation of amplitudes of the solitary waves has been shown graphically for different values of density and temperature of positrons, drift velocity and temperature of the ions.