Me. Koepke et al., ASYMMETRIC SPECTRAL BROADENING OF MODULATED ELECTROSTATIC ION-CYCLOTRON WAVES, Geophysical research letters, 21(11), 1994, pp. 1011-1014
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.