Oscillating two-stream instabifity of upper-hybrid laser radiation in a plasma

In the vicinity of a turning point, a high-power laser radiation (in the upper- hybrid mode) is unstable for short wavelength, purely growing perturbations, viz, oscillating two-stream instability. The nonlinearity in the low-frequency response arises through the parallel pondermotive force whereas in the high- frequency response it arises through the equation of continuity. In the limits of long and short perpendicular wavelengths, κ┴ρ_e< 1 and κ┴ρ_e > 1, the growth rates are found to be γ∞ │κ┴.V_0┴│², where ρ_e and V_0┴ are the electron Larmor radius and oscillatory drift velocity.