Date of Award

Spring 2016

Project Type

Dissertation

Program or Major

Physics

Degree Name

Doctor of Philosophy

First Advisor

Harlan E Spence

Second Advisor

Maurik Holtrop

Third Advisor

Lynn Kistler

Abstract

The dynamics of the radiation belts depend on a delicate balance of source and loss processes. One such source process that has been shown to be effective is local acceleration, where 10s-100s keV seed electrons are accelerated via wave-particle interactions up to energies >1 MeV. Historically, much of the focus of radiation belt research has been on the dynamics of these >1 MeV electrons, and the role and importance of the seed electrons has been largely overlooked. In this thesis, we use phase space density calculated using data from the Van Allen Probes, to directly investigate seed population for a variety of events. We begin by presenting a case study of the 17 March 2013 event, providing some of the first clear observations of the seed population during a local acceleration event. Next, we present results from the first ever statistical study of the radiation belt seed population from the first 26 months of data from the Van Allen Probes. Finally, we examine all the pieces of the acceleration process together to determine what conditions produce effective radiation belt acceleration. Our results clearly demonstrate that the seed population plays a critical role in governing the dynamics of the higher energy radiation belt electrons.

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