Oscillating two-stream instability of a plasma wave in ion-motion regime

It is known that the laser interactions with high-density plasmas can excite a large amplitude plasma wave near critical layer. This large amplitude plasma wave may be susceptible for oscillating two-stream instability by exciting a pair of two electrostatic sidebands and a purely growing low-frequency mode. We propose to revisit this study in the time scale of the order of ion-plasma period by incorporating the ion motion in estimation of the growth rate of the instability. The growth of plasma wave strongly modifies due the ion motion and thus the growth rate of the instability is modified in a specific parameter region. The present study shows that there is a narrow parameter space where the oscillating two-stream instability exists in this regime. (author)