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Cerenkov emissions of ion acoustic‐like waves generated by electron beams emitted during TSS 1R
Author(s) -
Huang C. Y.,
Burke W. J.,
Hardy D. A.,
Gough M. P.,
Olson D. G.,
Gentile L. C.,
Gilchrist B. E.,
Bonifazi C.,
Raitt W. J.,
Thompson D. C.
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/98gl00333
Subject(s) - physics , electron , ion , atomic physics , cherenkov radiation , plasma , beam (structure) , excited state , computational physics , optics , nuclear physics , detector , quantum mechanics
During the Tethered Satellite System reflight the Spacecraft Particle Correlation Experiment detected fluxes of energetic electrons and ions that were simultaneously modulated at low frequencies during firings of both the fast pulsed electron gun (FPEG) and the electron generator assembly (EGA). The modulations have been interpreted as signatures of large‐amplitude, ion acoustic‐like waves excited in Cerenkov interactions between electron beams and ambient plasmas as the shuttle moved at supersonic speeds across the ionospheric magnetic field. We present examples of particle modulations observed during steady beam emissions. Measurements show that (1) most electron modulations were at frequencies of several hundred Hertz and (2) ions modulated at similar frequencies appeared at spectral energy peaks during shuttle negative charging events. Detection of modulated ion fluxes confirms the Cerenkov emission hypothesis. Observed frequency variations indicate that the EGA beam underwent more spatial spreading than the FPEG beam.