Electromagnetic ion beam instabilities: Growth at cyclotron harmonic wave numbers

Journal Article · Thu Jan 01 04:00:00 EST 1987 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA092iA01p00117· OSTI ID:7078245

Smith, C W; Gary, S P

The linear theory of electromagnetic ion beam instabilities for arbitrary angles of propagation is studied, with 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). The 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. We show that the growth rates of both left- 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.

• Research Organization: Space Science Center, University of New Hampshire, Durham
• OSTI ID: 7078245
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 92:A1; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BEAMS
CYCLOTRON INSTABILITY
CYCLOTRON RESONANCE
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
HARMONICS
INSTABILITY
INSTABILITY GROWTH RATES
ION BEAMS
ION PLASMA WAVES
ION TEMPERATURE
ION WAVES
OSCILLATIONS
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
PLASMA WAVES
RESONANCE