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Electromagnetic ion beam instabilities - Growth at cyclotron harmonic wave numbersThe linear theory of electromagnetic ion beam instabilities for arbitrary angles of propagation is studied, with an emphasis on the conditions necessary to generate unstable modes at low harmonics of the ion cyclotron resonance condition. The present results extend the analysis of Smith et al. (1985). That paper considered only the plasma parameters at a time during which harmonic wave modes were observed in the earth's foreshock. The parameters of that paper are used as the basis of parametric variations here to establish the range of beam properties which may give rise to observable harmonic spectra. It is shown that the growth rates of both left-hand and right-hand cyclotron harmonic instabilities are enhanced by an increase in the beam temperature anisotropy and/or the beam speed. Decreases in the beam density and/or the core-ion beta reduce the overall growth of the cyclotron harmonic instabilities but favor the growth of these modes over the growth of the nonresonant instability and thereby enhance the observability of the harmonics.
Document ID
19870041539
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Smith, Charles W.
(New Hampshire, University Durham, United States)
Gary, S. Peter
(Los Alamos National Laboratory NM, United States)
Date Acquired
August 13, 2013
Publication Date
January 1, 1987
Publication Information
Publication: Journal of Geophysical Research
Volume: 92
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
87A28813
Funding Number(s)
CONTRACT_GRANT: NAS10-23726
CONTRACT_GRANT: NAGW-76
Distribution Limits
Public
Copyright
Other

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