Generation of extremely low frequency radiation by ionospheric electrojet modulation using powerful high-frequency heating waves
Article first published online: 20 JAN 2004
Copyright 2004 by the American Geophysical Union.
Volume 39, Issue 1, February 2004
How to Cite
2004), Generation of extremely low frequency radiation by ionospheric electrojet modulation using powerful high-frequency heating waves, Radio Sci., 39, RS1S32, doi:10.1029/2002RS002806., and (
- Issue published online: 20 JAN 2004
- Article first published online: 20 JAN 2004
- Manuscript Accepted: 4 JUN 2003
- Manuscript Revised: 15 MAY 2003
- Manuscript Received: 30 OCT 2002
- ELF radiation;
- electrojet current modulation;
- amplitude-modulation schemes;
- HF heating experiments
 Using amplitude-modulated high-frequency (HF) heating waves for electron heating, the conductivity of plasma and thus the embedded electrojet currents in high-latitude ionosphere can be modulated accordingly to set up the ionospheric antenna current for extremely low frequency (ELF) wave generation. Electron heating is hampered by inelastic collisions of electrons with neutral particles (mainly due to vibration excitation of N2), which cause the induced modulation current to remain at a low level. However, this inelastic collision loss rate drops rapidly to a low value in the energy regime from 3.5 to 6 eV. Thus, as the heating power exceeds a critical level, electron heating suddenly reaches an unexpected high level, resulting to a near step increase (of about 5 to 8 dB depending on the modulation waveform and frequency) in the spectral intensity of ELF radiation. The dependency of this critical HF heating-wave power on the modulation frequency is determined for three heating wave modulation forms: (1) rectangular wave, (2) sine wave, and (3) half-wave rectified wave.