Accession Number : AD0666648

Title :   A STUDY OF THE MECHANISMS OF WHISTLER PROPAGATION AND VLF EMISSION GENERATION.

Descriptive Note : Final rept., 1 Oct 66-30 Sep 67,

Corporate Author : STANFORD UNIV CALIF STANFORD ELECTRONICS LABS

Personal Author(s) : Helliwell,Robert A.

Report Date : JAN 1968

Pagination or Media Count : 14

Abstract : Extensions to the theory of vlf propagation in the magnetosphere with the effects of ions included have explained dispersion characteristics of magnetospherically-reflected (MR) whistlers, a complex phenomenon discovered recently with satellites. Because its dispersion depends on both electron and ion distributions, as well as on the static magnetic field, the MR whistler may be useful as a new tool in the study of the magnetosphere. It was found that the sharp cutoff of ducted whistlers at half the minimum gyrofrequency on the path is often accompanied by whistler amplification and generation of discrete vlf emissions near the cutoff frequency. Satellite data show that ducts are not required for the generation of discrete vlf emissions and that the region of generation most likely lies near the top of the line of force thru the satellite. Observations of artificially-stimulated emission on the ground show that their occurrence peaks up when the minimum gyrofrequency is twice the triggering frequency. A new theory was advanced to explain the generation of discrete vlf emissions and is based on cyclotron resonance between electrons in the kev energy range and a longitudinally propagating wave.

Descriptors :   (*WHISTLERS, PROPAGATION), MAGNETOSPHERE, INTERACTIONS, REFLECTION, ATTENUATION, SCIENTIFIC SATELLITES, IONOSPHERIC PROPAGATION, IONOSPHERIC DISTURBANCES, CHARGED PARTICLES, VERY LOW FREQUENCY

Subject Categories : Atmospheric Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE