| This thesis involves the study of large amplitude, short time duration electric fields observed in the Earth's magnetotail, and the low frequency waves that these electric fields are found to be embedded upon. The first component of this research consists of an in-depth statistical study of satellite observations from the Geotail spacecraft, to ascertain the location, polarization, and other statistical information regarding these spiky electric fields. This information is compared to 3 different theoretical models (mapping of electrostatic shocks, kinetic Alfven waves, and lower hybrid wave collapse) used to explain the formation and development of spiky electric fields, to ascertain which model best fits the Geotail observations. Statistical results indicate that the spiky electric fields are most consistent with the lower hybrid collapse mechanism. The second component of this study involves using a particle tracing code to trace ion trajectories through the magnetotail. Following the motion of individual ions allows one to construct distribution functions and their moments to gain better insight into magnetotail energization. Multiple magnetic field models are used to examine the dependence of distribution functions and plasma bulk parameters based upon the magnetic field model employed. A wave model, based upon spacecraft observations, has been added to the code to study what impact low frequency waves have on particle distributions and energization. Motivation for this work comes from the observation of low frequency waves in the magnetotail, their absence in other simulation studies, and the observation that spiky electric fields are found embedded in regions of low frequency waves. In addition, a model of the spiky electric fields, based upon the Geotail observations presented herein, is added to ascertain what impact these large electric fields have on particle distributions, energization and particle dynamics in the magnetotail. Results indicate that the choice of magnetic field model, the addition of low frequency waves and the inclusion of spiky electric fields all modify individual particle trajectories, particle distribution functions and moments. |
