Dust Acoustic Rogue Waves in a Cometary Environment with kappa Distributed Electrons and Protons

Abstract

Charged dust is present in almost all astrophysical and laboratory plasma environments. They alter the plasma charge density and also give rise to various modes of electrostatic waves and oscillations. In this paper we study the properties of Dust Acoustic Rogue Waves (DARW) in a cometary environment with positively and negatively charged dust components, kappa distributed - protons and electrons. Nonlinear Schrodinger Equation (NLSE) is derived using reductive perturbation method and analysed for modulational instability. The system is found to be modulationally unstable above some particular value of wave number($k=0.5$), after which the system is unstable. The solution for rogue waves is tested in this environment theoretically. Amplitude and structure of first and second order rogue waves are compared for various plasma parameters. Higher charge number of positive dust, $(z_+ > z_-)$ decreases the amplitude of RWs, while higher number density of positive dust $(n_+>n_-)$ ions increases it. As number density of proton $(n_i)$ increases the amplitude of RW decreases. Peak values increase with number density exponentially for positive and linearly for negative dust ions. It increases linearly with charge number of both positive and negative dust ions. Peak value decreases exponentially for number density of proton.