Instability Analysis of Obliquely Propagating Positron-Acoustic Solitary Waves in Superthermal Plasmas

The basic properties of the obliquely propagating positron-acoustic solitary waves (PASWs) and their multidimensional instability in magnetized electron-positron-ion plasmas consisting of immobile positive ions, mobile cold positrons, and superthermal (κ-distributed) hot positrons and electrons are investigated both numerically and analytically. By employing the reductive perturbation technique, the Zakharov-Kuznetsov equation is derived, which admits the solution of solitary waves. The fundamental features of PASWs are remarkably changed by the obliqueness, external magnetic field, superthermal parameter of electrons (κ_e), superthermal parameter of hot positrons (κ_p), ratio of the electron temperature to hot positron temperature (σ), ratio of the electron number density to cold positron number density (μ_e), and ratio of the hot positron number density to cold positron number density (μ_ph). It is also found that the instability criterion and the growth rate are significantly modified by the external magnetic field and the propagation directions of both the nonlinear waves and their perturbation modes. This paper can be useful to understand the nonlinear electromagnetic perturbations in space and laboratory plasmas.