Stabilization of the Two-Stream Instability in the Equatorial Electrojet

Stabilization of the two-stream instability in a weakly ionized plasma (equatorial electrojet) is studied using fluid equations. It is shown that a macroscopic quasilinear process acts to reduce the electron flow to a threshold level (ion sound speed), thereby stabilizing the instability. This result gives an explanation of constant Doppler shifts of radar echoes in the electrojet. It is further shown that the saturation level of the fluctuations agrees with that of observations.