Browsing by Author "Keith, Wayne Russell"

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    Development of an ion/electron plasma spectrometer
    (1999) Keith, Wayne Russell; Reiff, Patricia H.
    This thesis details the development of the Miniaturized Electrostatic DUal top-hat Spherical Analyzer (MEDUSA) instrument, including calibration, simulation, and data processing software. MEDUSA combines two-species observations with state-of-the-art miniaturization to achieve a low-cost, compact instrument capable of making the measurements that will be required in the future. Calibration of the instrument was performed during November 1997 and July 1998. In order to better understand the characteristics of the instrument, it was also modeled in detail with a modified 2.5 dimensional raytracing code. The production processing software is designed to archive the data into the standard Instrument Data File Set (IDFS) format of the Southwest Data Display and Analysis System (SDDAS). MEDUSA has so far proven itself to be a reliable, low-cost instrument capable of making the scientific measurements required for a better understanding of the behavior of the near-Earth particle environment.
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    Theory and measurements of the cusp/magnetopause current layer
    (2001) Keith, Wayne Russell; Winningham, J. David
    This thesis employs low-altitude satellite data taken in the northern and southern dayside magnetospheric cusps in order to determine if the magnetopause current layer has a continuous and identifiable footprint at low altitudes. The magnetopause current layer, at the outermost edge of the magnetosphere, is the site of interconnection between the Earth's geomagnetic field and the Interplanetary Magnetic Field of the magnetosheath. It is an active region in which the normal MHD assumptions cannot hold. Data from eight near-polar orbiting spacecraft are compared with predictions of a small wedge-shaped cusp at the dayside boundary of the polar cap. Precipitating particle data as well as high-energy particles, fields, and wave data are shown which are consistent with predicted features. A kinetic raytracing model and statistical survey of Astrid-2 and DMSP satellite data were also undertaken as part of this work and show this feature to be persistent and dependent on the IMF angle at the magnetopause, as expected. The study of this feature may lend new insight into the dynamics of the cusp and magnetospheric particle entry.