Theory for chorus generation by energetic electrons during substorms
Previous observations during magnetospheric substorm reveal the existence of relatively narrow band electromagnetic emission occurring slightly above and below one half of the electron cyclotron frequency in the equatorial magnetosphere beyond the plasmapause. Between these two bands of emission there exists a gap of much lower emission intensity. In this paper an interpretation is presented for these chorus observations wherein the lower emission band is represented by whistler noise and the upper emission band is described by the lowest harmonic of the ordinary mode. These emissions are assumed to be locally generated at the observation point. Both emission bands are excited by power law-distributed energetic electrons with a variable spectral index and a weak loss cone feature. The form of these energetic electrons is similar to the forms observed simultaneously with the chorus emissions. The calculated growth rates show a frequency distribution similar to that of the measured emissions. In addition, the same energetic electron distribution can also produce the electrostatic gyroharmonic emissions often seen by observers in conjunction with chorus emissions during substorms.
- Research Organization:
- Laboratory for Planetary Atmospheres, NASA Goddard Space Flight Center Greenbelt, Maryland 20771
- OSTI ID:
- 6617077
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 83:A8
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
MAGNETIC BAYS
WHISTLERS
CYCLOTRON FREQUENCY
ELECTRON PRECIPITATION
FREQUENCY DEPENDENCE
HARMONICS
PLASMA WAVES
CHARGED-PARTICLE PRECIPITATION
ELECTROMAGNETIC RADIATION
NOISE
OSCILLATIONS
RADIATIONS
RADIO NOISE
RADIOWAVE RADIATION
640203* - Atmospheric Physics- Magnetospheric Phenomena- (-1987)