Date of Award

Spring 2015

Project Type

Dissertation

Program or Major

Physics

Degree Name

Doctor of Philosophy

First Advisor

Marc R Lessard

Second Advisor

Harlan E Spence

Third Advisor

Thomas E Moore

Abstract

Understanding the role that the ionosphere plays in phenomena such as the development of auroral arcs and ion outflow is basic to the investigation of these processes and critical to the advancement of the broader study of magnetosphere-ionosphere coupling. Sounding rockets present an optimal platform for such studies, allowing low-cost access to altitudes that are difficult to reach by other means. Additionally, these measurements are key to validating current models and furthering understanding of the near-Earth space environment. This thesis highlights two particular rocket-borne instruments that measure electron populations in the ionosphere: the Electron Retarding Potential Analyzer (ERPA) and the Electron PLASma (EPLAS) instrument. It also presents analysis of the first in situ measurements of the ionospheric feedback instability (IFI) occurring within the Alfvén resonator in the vicinity of an auroral arc, a phenomenon that may play a role in the upward acceleration of ions and contribute to upflow. Another study highlights correlations between electron temperature and density and ion upflows. Simulation results, validated by rocket observations, show that increased ionospheric density inhibits the strength of the ambipolar field considered necessary for Type-2 ion outflow. Despite this however, the simulations show that increased densities result in increased net upflow fluxes. New radar data shows that sunlight effects might play an important role in controlling upflows, as photoionization can change ionospheric densities by as much as an order of magnitude seasonally.

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