Quenching of Natural Cyclotron Instability by Large Amplitude Monochromatic Waves Propagating in an Inhomogeneous Medium

Abstract

Recent experiments have shown that a long duration monochromatic wave generated by a high power VLF transmitter may quench natural magnetospheric hiss emissions over a frequency range Δf of the order of 50–;150 Hz below the transmitter frequency. We show that this effect can be interpreted by trapping, inside the monochromatic wave, of a certain amount of particles which were contributing to the generation of hiss in the equatorial region before the transmitter was switched on. The competition between the trapping and detrapping forces (the last one being due to the inhomogeneity of the medium) is studied. We show that the frequency range ΔF which is concerned by this effect is proportional to b², where b is The field intensity of the monochromatic wave. ΔF is also an increasing function of the transmitter frequency.