Spontaneous Emission of a Charged Particle Beam Inside a Plasma: Coherent and Incoherent Aspects

  • J. Lavergnat
  • R. Pellat
Part of the NATO Advanced Study Institutes Series book series (NSSB, volume 79)


Injection of charged particle beam into ionospheric plasma has revealed some unexpected behaviour of the radio waves emission (Cartwright and Kellog, 1974; Lavergnat et al, 1980). Two kinds of behaviour in time are observed for the wave envelopes: a Continuous emission’ with a one to one relation between the wave amplitude and the nominal beam current and a “pulsed emission” that reaches a maximum amplitude a few milliseconds after the beginning of an electron pulse and then decreases continuously to a background value. Along different experiments (Echo 1 and 2, Araks) both behaviours have been observed in two frequency ranges: in the whistler mode go ω < ωb, and in the plasma mode \( {\omega _P} < \omega < {({\omega _P}^2 + {\omega _b}^2)^{{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 2}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{$2$}}}} \) Pulsed emission will be the main topic of this paper. Apart from the collective processes spontaneous emission and specially the Cerenkov emission is a good candidate to explain the observations. Singh (1973) found by a crude computation of the incoherent Cerenkov emission electric field values which are a few orders of magnitude below the observed value and no possible explanation for the pulsed character. Alekhin and Karpman (1973) are the first who suggested that a beam with an infinitely sharp front and no spread in velocity can radiate a pulsed emission.


Pitch Angle Spontaneous Emission Ionospheric Plasma Pulse Emission Charged Particle Beam 
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Copyright information

© Plenum Press, New York 1982

Authors and Affiliations

  • J. Lavergnat
    • 1
  • R. Pellat
    • 2
  1. 1.L.G.E.St-Maur-des-FossésFrance
  2. 2.Centre de Physique ThéoriqueEcole PolytechniquePalaiseauFrance

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