Effect of ion streaming on the onset of the modulational instability

Abstract

The effect of ion streaming on the modulational instability (MI) of ion-acoustic waves in a collisionless unmagnetized plasma is studied. The nonlinear Schrödinger equation is derived by using the Krylov–Bogoliubov–Mitropolsky (KBM) perturbation technique. It is found that the value of the critical wavenumber kc is highly dependent upon the ion streaming velocity V0 and the system breaks into a number of stable and unstable regions. In the weak relativistic limit of V0, instability sets in for kc <1.47. It is reconfirmed that in the absence of ion streaming the modulational instability of ion-acoustic waves sets in at a critical wavenumber kc =1.47. UFaipxr