Electron Beam as a Source of Electrostatic Waves

The waves measurements performed during ionospheric electron beam injection experiments such as the ARAKS one (Lavergnat et al., 1980; Dechambre et al., 1980), show clearly two bands of electrostatic waves, the LF one, with frequencies lying below the electronic gyrofrequency f, and the HF one in the range fp < f < fh where fp is the electronic plasma frequency and fh the upper hybrid frequency.