ELECTROSTATIC WAVES IN IONOSPHERE EXCITED AROUND LOWER HYBRID RESONANCE FREQUENCY

The origin of lower hybrid resonance noise discovered by the Alouette I satellite is discussed. It is shown that in the ionosphere there are electrostatic waves propagating at large angles to the Earth's magnetic field with frequencies in the vicinity of the lower hybrid resonance. It is also shown that an electrostatic wave propagating slightly off the direction perpendicular to the magnetic field can grow due to the Landau instability process which is excited by high energy (∼10 keV) electrons streaming along the direction of the magnetic field of the Earth. The growing electrostatic wave thus triggered is shown to have a frequency band with a sharp lower cutoff at the lower hybrid resonance frequency, in agreement with observation. © 1969.