Linear and nonlinear propagation of ion-acoustic waves in a multi-ion plasma with positrons and two-temperature superthermal electrons

Linear and fully nonlinear features of ion-acoustic waves (IAWs) have been investigated by normal mode analysis (which is valid for extremely small amplitude limit) and pseudopotential approach (which is valid for arbitrary amplitude waves). The plasma is assumed to be composed of nonthermally κ (kappa)-distributed two-temperature electrons (termed as hot and cold), Maxwellian positrons, inertial ions and immobile negatively charged heavy ions. The pseudo-energy balance equation is derived from the fluid dynamical system of equations, and the properties of arbitrary amplitude ion-acoustic wave (IAW) excitations are examined. The basic features (width, amplitude, polarity, critical Mach number, speed, etc.) of IAWs are found to be significantly modified by the effects of positrons, heavy ions as well as by the effects of κ-distributed two-temperature superthermal electrons. The analytical and numerical results presented in this manuscript could be useful for explaining and understanding the basic features of solitary structures in astrophysical environments, where two-temperature superthermal electrons and thermal positrons exist.