Linear and Nonlinear Analysis of Electrostatic Waves in Plasma Systems with Effect of Non-Thermal Distribution of Particles

Abstract

Wave propagation has been an important subject in the field of plasma physics. Plasmas have a much higher variety of wave modes than ordinary matter because plasmas combine the aspects of a gas with electromagnetic forces. Moreover, the entanglement of particle motion with magnetic fields leads to wave types unknown in other fields of physics. In plasma, different types of electrostatic and electromagnetic waves can propagate depending on the absence and presence of external magnetic field and direction of propagation to the external magnetic field. It has also been well established by evidence from both space and laboratory plasmas that in some cases the particle distribution function is not usually Gaussian, rather it has a modified shape in the presence of fast particles. These plasma systems, where the velocity distribution of particles does not follow the typical Maxwell-Boltzmann velocity distribution, are termed as non-thermal or super-thermal plasmas. The main aim of this work is to conduct theoretical investigations for low frequency electrostatic waves in plasma systems with non-thermal particle distributions. The propagation of electrostatic ion acoustic mode has been considered in magnetized plasma. Two basic plasma models have been taken i.e., four components dusty plasma (containing positively and negatively charged dust particles, ions and electrons) and electron-positron-ion plasma. It is also important to mention here, that these plasma models are assumed to be slowly rotating about the external magnetic field, so that the effect of Coriolis force can be considered. In each case, the linear dynamics are investigated through the derivation of linear dispersion relation in the presence of nonthermal distribution of inertialess charged particles. It has been shown that the nonlinear dynamics of ion acoustic waves in magnetized plasmas are governed mainly by the Zakharov-Kuznetsov equation which admits the solitary wave solution. These exact and/or approximate (in the presence of collisions) time evolution solitary wave solutions are then investigated numerically under the influence of nonthermal particle distribution. The effects of other plasma parameters, such as rotational and collisional frequencies, on the dynamics of solitary waves are also carried out. The relevance of the present theoretical investigations to laboratory and space plasmas is also discussed in detail along with its importance and applications. Key Words: Electrostatic Waves-; Nonthermal Particles-; Dispersion Relation-; Solitary Waves-;