Influence of Vasyliunas-Cairns distributed non-thermal cold and hot electrons on the electron acoustic mode: a kinetic theory based exact numerical analysis

Abstract

Numerous observations from spacecraft missions have revealed that the space plasmas can be best modeled through the incorporation of nonthermal distributions. In the contemporary analysis, we investigate electron-acoustic waves (EAWs) in nonthermal plasmas. These waves propagate as a result of temperature difference between two electron species, commonly referred to as hot (\(T_{h}\)) and cold (\(T_{c}\)) electrons with \(T_{h}>T_{c}\). Both the hot and cold electrons are assumed to follow the Vasyliunas-Cairns distribution with considerations for limiting cases involving kappa and Maxwellian distributions. The Poison-Vlasov model is incorporated to calculate the longitudinal dielectric response function of electron-acoustic mode. Exact numerical analysis is performed to solve the dispersion relation equation which enables the calculation of dispersion and damping rate of electron-acoustic waves (EAWs). The influence of relevant parameters e.g., nonthermality parameters, the temperature ratio between hot and cold electrons, and the ratio of the number density of hot electrons to the total electrons is examined on the real and imaginary frequencies of the mode. In view of global modeling of naturally occurring space plasmas, this investigation contributes well to the understanding of heliospheric plasmas e.g., solar wind and magnetosphere.