Parametric excitation of a lower-hybrid drift wave in the ionosphere

Parametric excitation of a lower-hybrid drift (LHD) wave has been studied in the ionosphere due to the propagation of a high-frequency electromagnetic (EM) pump wave (with wave number k0∼0) in the presence of the electron collisions. It is considered to be a four wave interaction process of LHD, electromagnetic pump wave, and two electron plasma waves as sidebands. Nonlinear growth rate of a LHD wave is found to be higher for 1<krLe<1.5 as compared to the case krLe<1, where k and rLe, respectively, are the wave number of the LHD wave and electron Larmor radius. Wavelengths of the excited lower-hybrid drift waves lie in the range of the various irregularities observed by Jicamarca [Farley et al., J. Geophys. Res. 75, 7199 (1970)], and Altair and Tradex radars [R. T. Tsunoda, Geophys. Res. Lett. 7, 848 (1980)]. It is seen that the nonlinear growth rate drops significantly in the presence of the electron collisions. copyright 1995 American Institute of Physics