Accession Number : AD0710742

Title :   INSTABILITIES OBSERVED IN LOWER-E-LAYER ALKALI-PLASMA-CLOUD RELEASES AND THEIR IMPLICATIONS REGARDING SPORADIC E,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Davis,John R.

Report Date : 28 JUL 1970

Pagination or Media Count : 111

Abstract : The report describes a study of gun- and rocket-emplaced alkali plasma clouds in the 85-105 km altitude region of the ionosphere. The object of the investigation is to study the small-scale (tens-of-meters), short-term (fractions-of-seconds) irregular motion of the magnetofluid in the lower E layer. Motions on this spatial and temporal scale are known to be responsible for radiofrequency scattering at E-layer heights, and it has been suspected that they are important in the appearance and evolution of the sporadic-E layer. The resolution which is necessary to discern motions on the scale indicated was afforded by decameter- and meter-wavelength coherent-pulse-doppler radar. A survey of possible instability mechanisms which can explain the spatial and temporal scales of the irregular motion observed in Phase III of plasma cloud evolution leads to the conclusion that a dissipative instability involving crossed electric and magnetic fields in the presence of a properly oriented plasma density gradient is the most likely candidate. It is found that the observed tens-of-meters instability wavelengths and tenths-of-seconds growth times are predicted by this mechanism, and curves of these parameters are presented for various altitudes, electrostatic field intensities, and wavelengths. (Author)

Descriptors :   (*IONOSPHERE, MOTION), OSCILLATION, PLASMAS(PHYSICS), RADIOFREQUENCY INTERFERENCE, CHARGED PARTICLES, IONOSPHERIC PROPAGATION, DOPPLER RADAR, RADAR CROSS SECTIONS, BACKSCATTERING, IONIZATION, STABILITY, CESIUM, NITRATES

Subject Categories : Atmospheric Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE