Modulational Instability Of Ion Acoustic Waves In A Multi-Species Collisionless Unmagnetized Plasma Consisting Of Nonthermal And Isothermal Electrons

A nonlinear Schrodinger equation is derived to study the modulational instability of finite amplitude ion acoustic waves in a collisionless unmagnetized plasma consisting of warm adiabatic ions and two distinct populations of electrons, one is due to distributed energetic electrons described by Cairns et al. [Geophys. Res. Lett. 22, 2709 (1995)] which generates the energetic electrons, and the other is the isothermal electrons. The instability condition and the maximum growth rate of instability have been investigated numerically. We have studied the effect of each parameter of the present plasma system on the maximum growth rate of instability. In particular, it is found that the maximum growth rate of instability increases with the increasing values of the wave number for any given set of values of the parameters associated with the present plasma system. It has also been shown that for any fixed value of the wave number, the maximum growth rate of instability increases with increasing values of the nonthermal parameter associated with the Cairns distributed energetic electrons. Published by AIP Publishing.