Zakharov-Kuznetsov-Burgers equation in superthermal electron-positron-ion plasma

Properties of three-dimensional ion-acoustic solitary and shock waves accompining electron-positron-ion magnetoplasma with high-energy (superthermal) electrons and positrons are investigated. For this purpose, a Zakharov-Kuznetsov-Burgers (ZKB) equation is derived from the ion continuity equation, ion momentum equation with kinematic viscosity among ions fluid, electrons, and positrons having kappa distribution together with the Poisson equation. The dependence of the solitary and shock excitations characteristics on the parameter measuring the superthermality kappa, the ion gyrofrequency Omega, the unperturbed positrons-to-ions density ratio nu, the viscosity parameter eta, the direction cosine a, the ion-to-electron temperature ratio sigma (i) , and the electron-to-positron temperature ratio sigma (p) have been investigated. Moreover, it is found that the parameters kappa, Omega, nu, eta, and a lead to accelerate the particles, whereas the parameters sigma (i) and sigma (p) would lead to decelerate them. Numerical calculations reveal that the nonlinear pulses polarity are always positive. This study could be useful to understand the nonlinear electrostatic excitations in interstellar medium.