ASYMMETRIC SPECTRAL BROADENING OF MODULATED ELECTROSTATIC ION-CYCLOTRON WAVES

Modulated, current-driven, electrostatic ion-cyclotron (CDEIC) waves a re shown to exhibit amplitude and frequency modulation, spectral broad ening, and time-averaged frequency pulling. The observed spectral broa dening is asymmetric and sensitively dependent on the driving frequenc y. Qualitative features of the experimental data are reproduced by the forced van der Pol equation and are explainable using processes assoc iated with driven self oscillations. These results may be relevant to ionospheric modification experiments involving the controlled modulati on of the natural electrojet.