[PDF] Ionospheric Modification By High Power Radio Waves eBook

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Page : pages
File Size : 36,73 MB
Release : 1981
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Powerful, high-frequency radio waves have been used to temporarily modify the ionosphere. Thermal and parametric interactions have led to a diverse range of observed phenomena, including generation of density striations and artificial spread-F, enhancements of electron plasma waves, production of extrathermal electron fluxes and enhanced airglow, modification of the D-region temperature and densities, wideband signal attenuation, and self-focusing and scattering of the electromagnetic waves. The physics of ionospheric modification by high-power radio waves is reviewed in the context of our current theoretical understanding; disturbance generation mechanisms are qualitatively described. In addition, results of recent experiments are summarized in which ionospheric irregularities are generated and their evolution and decay processes investigated in detail. The effects and potential controlled applications of these HF ionospheric modifications for various RF systems studies are discussed. The C3I scientific community provides an important motivation for these ionospheric modification studies; their increased interaction and active participation in experimental design and interpretation are encouraged.

Author : Gary S. Sales
Publisher :
Page : 44 pages
File Size : 25,94 MB
Release : 1986
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A special experiment was carried out using a high powered transmitter and a high gain rhombic antenna to heat the ionosphere at a distance of 1300 km from the transmitter. A Digisonde ionospheric sounder was located at the midpoint to sense any changes that might occur in the ionosphere at the heating cycle period of ten minutes. The measured phase data was processed using spectrum analysis in an attempt to detect this ten minute period. The results are not conclusive but there is some indication that the heating period was detected only during the nighttime in agreement with theoretical prediction. Keywords: Ionosphere; Modification; High frequency; Propagation.

Author : P. A. Bernhardt
Publisher :
Page : 15 pages
File Size : 31,88 MB
Release : 1990
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Ionospheric plasma density irregularities can be produced locally by chemical releases from space vehicles or remotely by a beam of high power radio waves transmitted from the ground. F-region plasma modification occurs by (1) chemically enhancing the electron number density, (2) chemically reducing the electron population, or (3) physically convecting the plasma from one region to another. The three processes (production, loss, and transport) can determine the effectiveness of ionospheric chemical releases and high frequency electromagnetic wave transmissions in subtle and surprising ways. Initially, a chemical release produces a localized change in plasma density and high power radio waves heat the electrons to yield enhanced transport from pressure gradients in the heated region. Subsequent processes, however, can lead to enhanced transport in chemically modified regions and modified reaction rates in the regions affected by high power radio waves.

Author : Kenneth Davies
Publisher : IET
Page : 612 pages
File Size : 31,66 MB
Release : 1990
Category : Science
ISBN : 9780863411861

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This introductory text replaces two earlier publications (Davies 1965, 1969). Among the topics: characteristics of waves and plasma, the solar-terrestrial system, the Appleton formula, radio soundings of the ionosphere, morphology of the ionosphere, oblique propagation, importance of amplitude and phase, earth-space propagation. Annotation copyrighted by Book News, Inc., Portland, OR