In this thesis, radial dependence of variations in anisotropies for pitch angle distributions (PAD) of electrons at the dipolarization sites in the Earth’s tailside is investigated through statistical analysis on observations of THEMIS (Time History of Events and Macroscale Interactions during Substorms) mission from the year of 2008 to 2011. The data of electrons with energy ranges from a few eV to MeV detected by the charged particle instruments on THEMIS probes, the electrostatic analyzer (ESA) and the solid state telescope (SST), are adopted. The primary focus is on how the anisotropy ratio between the dipolarization period and before the dipolarization starts distributes with L-shells and field line lengths the THEMIS probes located. The results show that a specific dependence feature does exist for the energy range around a few keV and possible theoretical interpretations are discussed.
|Date of Award||2017|
|Supervisor||Bing-Chih Chen (Supervisor)|