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Packets of cyclotron waves induced by electron beam injection from the space shuttle 1. Linear theory
Author(s) -
Mourenas D.,
Béghin C.
Publication year - 1991
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/90rs02580
Subject(s) - physics , cyclotron , wave packet , computational physics , electron , harmonics , atomic physics , quantum mechanics , voltage
Measurements of high‐frequency wave emissions were made on board Spacelab 1 during artificial electron beam injection from the shuttle bay. The most unusual kind of spectrum is considered here, i.e., packets of electron cyclotron waves occurring at successive harmonics of the plasma frequency. Using a linear theory, it is shown that the emissions consist of the well‐known electronic Bernstein modes, which are thought to be generated by an interaction between the neutralization return current and the ambient ionospheric plasma, and not directly by the primary beam. A simplified model of the electron velocity distribution function of the return current is developed. Then, a numerical resolution of the dispersion equation is undertaken, with the experimental constraint that the waves have to fit the “rendezvous” condition with the instruments flying on board the orbiter. The observed electron cyclotron emissions, as well as their amplitude modulation around the fundamental of the plasma frequency, are found to be easily explained by such a linear theory. A companion paper [ Mourenas and Béghin , this issue] will propose a nonlinear treatment of the same mechanism, which is thought to be responsible for the production of upper harmonic packets.