Date of Award

Spring 1999

Project Type

Dissertation

Program or Major

Physics

Degree Name

Doctor of Philosophy

First Advisor

Kristina A Lynch

Abstract

In this thesis we discuss the results of the Sudden Atom Layers (SAL) sounding rocket, launched from Puerto Rico the evening of February 19, 1998, as part of the Coqui II sounding rocket campaign. A charged dust detector was constructed and flown on the Sudden Atom Layers (SAL) sounding rocket. The existence of charged dust population has implications for many upper atmospheric processes, including the formation of sporadic atom layers (Na s), thin layers of neutral atomic metal which form in the Earth's mesosphere. In particular we focus on the interesting results from the charged dust experiment and the electric field measurement.

The dust detector, a sensitive Faraday cup, used a synchronous detection method to measure a limited mass range of charged dust. Other instruments on the SAL payload measured the in-situ electric fields, plasma density and neutral sodium density. Ground measurements taken at Arecibo confirmed the presence of a double sporadic sodium layer and a sporadic E layer at the time of the rocket launch. These layers were also observed in-situ. The dust detector measured a broad layer of positively charged dust ( ≈ 20 cm-3) in the vicinity of both the sporadic sodium and sporadic E layers. This charged dust experiment has provided the first observation of charged meteoric dust in the tropical mesosphere.

While the rocket data is not conclusive evidence of a correlation between mesospheric dust and sporadic sodium layer formation, it is an in-situ observation of the existence of mesospheric dust near a sporadic atom layer, as predicted by some Nas models. We discuss the characteristics of the observed charged dust layer, including the unexpected positive charge and inferred physical structure, and the observed correspondence between this layer and other mesospheric layering observed at the same time. We also report on a measurement of the gradient drift plasma instability observed on the top side of the accompanying sporadic E layer. The local nonlinear growth rate for the instability was calculated, and wavelength inner and outer scales determined.

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