LOWER-HYBRID RESONANCE WAVE EXCITATION BY WHISTLERS IN THE MAGNETOSPHERIC PLASMA

A new theory of lower hybrid resonance (LHR) wave excitation by whistl ers in magnetospheric plasma is developed. Two time dependent differen tial equations, which have a form of linear wave interaction between q uasi-longitudinal whistler-mode waves and quasi-electrostatic LHR wave s in a cold plasma with small-scale density irregularities, are derive d and solved by the method of successive approximations. Fundamental o bservational results on LHR wave excitation by whistlers, such as the lower cutoff frequency of excited waves and the pronounced spectral ma ximum near the LHR frequency, as well as the close connection of the e xcitation process with small-scale plasma density irregularities are e xplained by the present theory in a consistent manner.