LOWER-HYBRID OSCILLATIONS IN MULTICOMPONENT SPACE PLASMAS SUBJECTED TO ION-CYCLOTRON WAVES

It is found that in multicomponent plasmas subjected to Alfven or fast magnetosonic waves, such as are observed in regions of the outer plas masphere and ring current-plasmapause overlap, lower hybrid oscillatio ns are generated. The addition of a minor heavy ion component to a pro ton-electron plasma significantly lowers the low-frequency electric wa ve amplitude needed for lower hybrid wave excitation. It is found that the lower hybrid wave energy density level is determined by the nonli near process of induced scattering by ions and electrons; hydrogen ion s in the region of resonant velocities are accelerated; and nonresonan t particles are weakly heated due to the induced scattering. For a giv en example, the light resonant ions have an energy gain factor of 20, leading to the development of a high-energy tail in the H+ distributio n function due to low-frequency waves.