Modulational instability of ion-acoustic-waves in two electron temperature plasmas

The envelope properties of ion-acoustic waves in a two-electron temperature plasma are studied. The nonlinear Schroedinger equation describing the envelope of these waves is obtained from the plasma fluid equations by employing the Krylov-Bogoliubov-Mitropolsky perturbation method. It is shown that the ion-acoustic waves can be modulationally unstable or stable depending on the ratios of the densities and the temperatures of the hot and cold electron components. Even a small fraction of the cold electron component can drastically affect the stability of the system. (author)