EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Bell & Ngo 1988
Bell, T.F. and Ngo, H.D. (1988). Electrostatic waves stimulated by coherent VLF signals propagating in and near the inner radiation belt. Journal of Geophysical Research 93: doi: 10.1029/88JA01091. issn: 0148-0227.

Recent ISEE 1 satellite observations indicate that electrostatic waves are commonly stimulated by coherent VLF electromagnetic whistler mode signals propagating on magnetic field lines in, and near, the inner radiation belt. Evidence for the existence of the electrostatic waves consists of apparent bandwidth increases of up to 300 Hz in the electric field component of 10 to 15 kHz signals from ground-based VLF transmitters observed in the inner radiation belt. During the period July through December 1983, the effect was observed on 60% of the satellite orbits which penetrated the inner radiation belts (L≤2), and in many cases the effect was observed continuously from the magnetic equator at L~2 down to perigee. The effect appeared in signals propagating from sources in both the northern and southern hemispheres.

In general, the stimulated electrostatic waves were delayed with respect to the input signal by 50 ms to 500 ms, suggesting that the generation region was removed from the satellite location. The total apparent bandwidth Δ&ohgr; of the stimulated electrostatic waves observed on any given satellite pass was found to be roughly proportional to the local magnitude of the Earth's magnetic field, but the constant of proportionality varied over a 4-to-1 range for the complete data set. In general at any given time, signals of similar frequency and propagation direction exhibited similar Δ&ohgr;.

However, signals of similar frequency propagating in opposite directions occacionally exhibited marked differences in Δ&ohgr;. Characteristics of the stimulated wave structure coincide closely with those reported in a recent study of low altitude satellite VLF wave data (Bell et al., 1983). In consonance with this earlier work it is hypothesized that the electrostatic waves are stimulated as the electromagnetic whistler-mode input waves scatter from magnetic-field-aligned plasma density irregularities which exist within the inner radiation belt. It is further hypothesized that once generated, these short wavelength electrostatic waves may then interact with energetic radiation belt particles, producing particle pitch angle scattering and precipitation. The induced precipitation could result in ionospheric plasma density enhancements, and upward diffusion of cold plasma from these enhancements may produce new magnetic-field-aligned density irregularities. This feedback process may provide a mechanism for the creation and maintenance of magnetic-field-aligned plasma density irregularities in the inner radiation belts. ¿ American Geophysical Union 1988

BACKGROUND DATA FILES

Abstract

Keywords
Magnetospheric Physics, Plasma waves and instabilities, Magnetospheric Physics, Magnetosphere/ionosphere interactions, Electromagnetics, Scattering and diffraction, Electromagnetics, Wave propagation
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit