Parametric decay of a whistler wave at the difference frequency of two electromagnetic waves in a plasma

A large-amplitude whistler wave excited at the difference frequency of two high-frequency electromagnetic pump waves is shown to decay parametrically into a lower-hybrid wave (LHW) and a low-frequency ion-Bernstein wave (IBW) in a collisionless magnetized multi-ion-species plasma,. A nonlinear dispersion relation describing this parametric interaction process is derived. The low-frequency ponderomotive force along the direction of the external magnetic field leads to the dominant coupling. Possible applications to ion heating in the ionosphere, in the earth's magnetosphere and in laboratory plasmas are discussed.