Modulational instability of obliquely modulated ionacoustic waves in a two-electron-temperature plasma

The unstable domain in the (k, Ø) plane for oblique modulation of ion-acoustic waves, in a two-electron-temperature plasma, is investigated using the KBM perturbation technique. It is shown that, in a collisionless plasma, the maximum growth rate for the modulational instability, for large carrier-wave amplitudes (a₀ 0·1), exceeds the electron Landau damping rate for sufficiently oblique modulation.