On the role of the energy of suprathermal electrons in the generation of auroral kilometric radiation

Journal Article · Mon May 01 00:00:00 EDT 1989 · Journal of Geophysical Research; (USA)

DOI:https://doi.org/10.1029/JA094iA05p05327· OSTI ID:5830853

Wong, H K ^[1]; Krauss-Varban, D; Wu, C S ^[2]

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1. Southwest Research Institute, San Antonio, TX (USA)
2. Univ. of Maryland, College Park (USA)

Recent satellite observations have identified second harmonic auroral kilometric radiation, in part in source regions where the electron plasma frequency is known to be much smaller than the electron cyclotron frequency ({omega}{sub pe} {le} 0.2 {Omega}{sub e}). These observations as well as certain observations of O mode fundamental radiation have raised some controversy because conventional discussions predict their generation to be more favorable in a high-density plasma, the fundamental X mode dominating otherwise. In this work the authors reexamine the relativistic dispersion equation based on the cyclotron maser theory for a DGH distribution of energetic electrons. The purpose is to identify and understand the physical conditions under which fundamental O mode and second harmonic X mode radiations can dominate over fundamental X mode emission in low-density source regions. They find that the energy of the auroral electrons can play a significant role in determining the dominant wave mode. The temporal and spatial growth rates of both the fundamental O mode as well as the second harmonic X mode remain high for surprisingly low energies (several hundred electron volts) of the suprathermal electrons, while the fundamental X mode is suppressed for energies {approx lt} 1 keV due to its relativistic resonance condition. This finding can have significant implications to the theoretical study of magnetospheric radio environments in general.

• OSTI ID: 5830853
• Journal Information: Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 94:A5; ISSN 0148-0227; 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
AURORAE
AURORAL ZONES
CYCLOTRON INSTABILITY
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
INSTABILITY
LANGMUIR FREQUENCY
LEPTONS
LONG WAVE RADIATION
ORIGIN
PLASMA
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
RADIATIONS
RADIOWAVE RADIATION
SATELLITES