Date of Award

Fall 2001

Project Type


Program or Major


Degree Name

Doctor of Philosophy

First Advisor

Richard L Kaufmann


The purpose of this study is to investigate velocity space distribution functions in space plasmas. Orbit tracing methods are used to generate self-consistent models of several different magnetic and electric field configurations. Fast flows in the magnetotail are selected to be modeled using a relatively thin current sheet compared with quiet times. Four different electric fields are imposed, varying in characteristic thickness and magnitude. Using these four particle based models we were able to generate velocity distribution functions that show clear evidence of non-adiabatic features that depend on the electric field characteristic width. Several years of Geotail Comprehensive Plasma Instrumentation (CPI) data were subsequently examined to find data sets for comparison. Four events out of more than twenty are chosen for closer comparison. It is shown that the modeled distributions are very similar to the spacecraft data. Non-adiabatic orbits can be interpreted as the cause of these features, and an understanding of how they interact with the local electric fields is reached.