Positron-acoustic solitary stability in magnetized plasmas with nonthermal particles

Abstract

This study investigates the dynamics of positron-acoustic waves (PAWs) in a magnetized, collisionless, four-component plasma system consisting of static ions, mobile cold positrons, and nonthermal distributed hot electrons and hot positrons. The governing equations for the plasma system are derived, and the Zakharov-Kuznetsov (ZK) equation is deduced using stretched coordinates and perturbation expansions. The phase speed of PAWs is analyzed, showing its dependence on the nonthermal parameter, hot-to-cold positron equilibrium density ratio, and temperature ratios. The solitary wave solutions of the ZK equation are obtained, and the amplitude, width, and associated electric field of the solitary waves are examined. The energy of PAWs is calculated, highlighting the influence of the density and temperature of hot positrons and electrons. An instability analysis is conducted using the small-k expansion perturbation approach, revealing the dependence of the instability growth rate on system parameters such as the magnetic field and rotation angle. The findings provide insights into the complex dynamics of PAWs in multi-component plasmas, relevant to various astrophysical (viz., ionosphere, lower part of magnetosphere, auroral acceleration regions, supernovas, pulsar environments, cluster explosions, active galactic nuclei, etc.) and laboratory plasma environments, such as multi-dipole confined hot cathode discharge.