Date of Award

Spring 1986

Project Type

Dissertation

Program or Major

Physics

Degree Name

Doctor of Philosophy

Abstract

Simultaneous upflowing hydrogen and oxygen beams of ionospheric origin are seen at altitudes near 3.3 R(,e) in the auroral zone by the DE-1 satellite. The beam observations indicate that, in addition to bulk acceleration, substantial heating in both hydrogen and oxygen has taken place either near or above the cold ionospheric source region. Velocity space distributions of the two ion species show hydrogen having a higher streaming velocity than oxygen, but also a smaller streaming energy. The region of velocity space between the two ion beam peaks has been filled in, with ions in the oxygen beam having been accelerated and hydrogen ions having been decelerated. This suggests wave-particle interactions at lower altitudes enabled the transfer of energy from the hydrogen to the oxygen. Maxwellian fits to the beam distributions are used to study the stability of the beams with respect to various low frequency electromagnetic waves. By identifying the growing wave modes generated by the observed distribution functions, one can obtain information about any heating that is taking place in the vicinity of the satellite. This also gives one information on the nature of the heating mechanism at lower altitudes. Using the homogeneous plasma approximation, the Maxwellian fits produce a weak instability of the electrostatic slow hydrogen ion acoustic wave. The wave resonates both with hydrogen and oxygen and can heat both species by quasilinear diffusion. This process seems to be a viable one at satellite altitudes but is not responsible for the bulk of the heating which took place at lower altitudes.

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