Head-on interaction of electron-acoustic solitons with superthermal trapped hot electrons

Abstract

Plasma systems are known to be nonlinear mediums which support large number of nonlinear waves, electron-acoustic wave is of them which exists in a two-electron temperature plasma. Two-electron temperature plasma composed of cold electrons, hot electrons following a non thermal distribution and stationary ions. Here, we talk about the head-on interaction of electron-acoustic solitons in presence of non-thermally trapped hot electrons, which has drawn a lot of attention because of its importance in variety of space and laboratory systems. In various plasma systems, interactions between solitary waves, which are nonlinear in na ture, are crucial for the transfer of energy and momentum. In such systems, the distribution of hot electrons signi cantly a ects the plasma's overall behavior. In this thesis, we investigate the phase shifts in electron-acoustic solitary waves for two di erent non-thermal distributions of trapped hot electrons. In this regard, rst we present a review of the HoC of two electron acoustic solitons in an un-magnetized and collisonless plasma with hot electrons obeying a trapped/vortex-like distribution. An extended PoincareLighthill-Kuo (PLK) method is em ployed to derive two trapped Korteweg-de Vries (KdV) equations for two solitons propagating in opposite directions. Numerical ndings reveal that the phase shifts in electron-acoustic solitons depend on both the amplitudes of colliding waves where the wave with greater am plitude experiences smaller phase shift. Then, considering the trapped kappa distribution of hot electrons, we nd the phase shifts in two EA solitary waves. Separate calculations are performed for two di erent systems, for rst instance we investigate the isothermal plasma for which the cold electron pressure has the form pc = nckBTc where kBTc is constant, and in second case, cold pressure is taken as itself a variable that is governed by adiabatic equation of state. Model equations governing both the systems are solved by extended PLK method to get their respective trapped KdV equations and solutions of right-going and left-going EA solitions. Solitonic pro les for two-dimensional and three-dimensional interactions and density plots of potential are depicted for various values of nonthermal (κ) and trapping (β) parameters. Phase shifts are also calculated numerically and found the phase shifts are independent of trapping parameter, however, the density ratio, temperature ratios and su perthermality parameter have a signi cant impact on it. These parameters are taken from the space environments like dayside auroral zone and Earth's magnetopause to gure the phase shifts in EA solitary waves.