Accession Number : AD0610424

Title :   DISCRETE VLF EMISSIONS FROM THE UPPER ATMOSPHERE,

Corporate Author : STANFORD UNIV CALIF STANFORD ELECTRONICS LABS

Personal Author(s) : Brice,Neil M.

Report Date : AUG 1964

Pagination or Media Count : 161

Abstract : A new mechanism for the generation of emissions by energetic electrons--the transverse-resonance plasma instability--was found. The existence of this instability depends on the electron velocity component transverse to the earth's magnetic field rather than the component along the field. The emitted signals propagate along the field in a direction opposite to the drift of the electrons. This instability is nonconvective and, as such, has an inherent advantage over mechanisms previously suggested for explaining the generation of discrete emissions. The hypothesis that discrete VLF emissions are generated by this mechanism leads to a qualitative explanation of their diurnal variation, and much additional support for this hypothesis is found in the data. All the mechanisms considered for the generation of emissions that are observed on the ground involve resonances in the interaction between energetic electrons and right circularly polarized (whistler-mode) signals propagating quasilongitudinally. An investigation is made of VLF emissions recorded by satellites. Two distinct types of signals that are observed only in satellites were found.

Descriptors :   (*IONOSPHERIC PROPAGATION, VERY LOW FREQUENCY), (*ATMOSPHERICS, VERY LOW FREQUENCY), ELECTROMAGNETIC RADIATION, WAVE PROPAGATION, UPPER ATMOSPHERE, ELECTRONS, IONS, WHISTLERS, MAGNETIC FIELDS, DIURNAL VARIATIONS, RESONANCE, MAGNETOHYDRODYNAMICS

Distribution Statement : APPROVED FOR PUBLIC RELEASE