Growth of electron plasma waves above and below f/sub p/ in the electron foreshock

Journal Article · Fri Jul 01 04:00:00 EDT 1988 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA093iA07p07307· OSTI ID:7125037

Cairns, I H; Fung, S F

With increasing penetration into the electron foreshock the characteristics of the electrostatic waves driven by streaming electrons change continuously from the familiar intense waves near the electron plasma frequency f/sub p/ to weak bursts of broadband waves initially significantly above f/sub p/ and then well below f/sub p/. Growth well below f/sub p/ has been demonstrated theoretically for slow, cold electron beams, and the broadband waves below f/sub p/ in the foreshock have been interpreted in terms of the very cold or sharp ''cutoff'' feature of a cutoff distribution for small cutoff speeds. However, an approximate theoretical criterion indicates that the electron beams studied hitherto are unstable to reactive rather than kinetic growth, thereby favoring very narrow-band growth contrary to the observed broadband growth. In this paper we determine conditions for kinetic growth well above and below f/sub p/ for both cold and warm beams over a wide range of beam densities and speeds. We verify that kinetic growth below f/sub p/ is possible for cold, slow beams and for warm, dense beams (over wide range of beam velocities).

• Research Organization: Department of Physics and Astronomy, University of Iowa, Iowa city
• OSTI ID: 7125037
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 93:A7; 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
DISTRIBUTION FUNCTIONS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRON BEAMS
ELECTRON PLASMA WAVES
FUNCTIONS
INSTABILITY GROWTH RATES
LANGMUIR FREQUENCY
LEPTON BEAMS
PARTICLE BEAMS
PLASMA WAVES
SHOCK WAVES
SOLAR ACTIVITY
SOLAR WIND