Electron acceleration in the magnetosphere. Ph. D. Thesis

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:6076624

Hui, C H

The mechanisms of auroral electron acceleration are studied by two particle simulation models. The first model is a two-dimensional hybrid-kinetic description used to study the self consistent electron kinetics of Alfven waves on the electron inertial scale. The ions are assumed to follow a fluid description and the parallel electron motion is treated kinetically using particle-in-cell techniques. In this model the electron plasma mode is eliminated and only the physics of the Alfven waves is retained. For a cold plasma, it is found that oblique Alfven waves break due to finite electron inertia. The consequence of wave breaking is the formation of an electron beam which can be unstable to the beam-plasma instability. The electrons supporting the parallel current thermalize into a non-Maxwellian distribution with an energetic tail up to several keV, assuming a reasonable magnetospheric Alfven speed. In hot plasma simulations, electron trapping is the principal mechanism of electron acceleration. It is proposed that wave breaking or electron trapping of oblique Alfven waves at 1 R[sub E] can result in electron acceleration and may explain some observed auroral phenomena. The second model is a two-dimensional high frequency magnetized electron plasma particle code, which is used to investigate the parametric coupling of electromagnetic modes to the upper-hybrid and electrostatic whistler modes. A large amplitude X-mode generated by auroral kilometric radiation is shown to excite the electrostatic whistler wave and Z-mode by a parametric instability. The parallel electric field of the electrostatic whistler wave can cause the wave to break and pitch angle scatter electrons into the loss cone. This may account for the electron precipitation of diffuse aurora.

• Research Organization: Cornell Univ., Ithaca, NY (United States)
• OSTI ID: 6076624
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCELERATION
ALFVEN WAVES
AURORAE
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC FIELDS
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
HYDROMAGNETIC WAVES
INSTABILITY
LEPTONS
MATHEMATICAL MODELS
NOISE
PLASMA INSTABILITY
PLASMA WAVES
RADIATIONS
RADIO NOISE
RADIOWAVE RADIATION
TRAPPING
TWO-DIMENSIONAL CALCULATIONS
WHISTLERS