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Radial diffusion of radiation belt electrons in three dimensions.

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Call No.	QC809.V3 P47 2004
Author	Perry, Kara Lynn.
Title	Radial diffusion of radiation belt electrons in three dimensions.
Date	2004
Abstract	It is becoming increasingly important to understand the dynamics of radiation belt energetic particles given their potentially hazardous effects on satellites and our ever-increasing dependence on those satellites. There is a need to determine whether existing two-dimensional models are adequate in estimating the dynamics of the radiation belts or if a three-dimensional model is required. Discussion of general space physics and radiation belt topology is followed by an account of existing models and how these models can be improved by extending dynamic calculations from two dimensions to three. A model is then developed describing magnetic and electric fields associated with poloidal mode Pc5 ULF waves. The frequency and L dependence of the ULF wave power is included in this model by incorporating published ground-based magnetometer data. The influence of ultra low frequency (ULF) waves in the Pc5 frequency range on radiation belt electrons in a dipole magnetic field is examined. This is the first analysis in three dimensions utilizing model ULF wave electric and magnetic fields in the guiding center trajectories of relativistic electrons. It is demonstrated here that realistic spectral characteristics play a significant role in the rate of diffusion of relativistic electrons via drift resonance with poloidal mode ULF waves. Radial diffusion rates including bounce motion are calculated for α eq ≥ 50° (λ ≤ 20°). Energy, L and pitch angle dependence of diffusion rates are calculated for L-independent, L-dependent, frequency independent and frequency dependent field power. During geomagnetic storms when ULF wave power is increased, ULF waves are a significant driver of increased fluxes of relativistic electrons inside geosynchronous orbit. Diffusion time scales obtained here, when frequency and L dependence compared to observations of ULF wave power is included, support this conclusion. A compression is then added to the dipole field model and diffusion rates are compared to equatorial plane results. When radial and frequency dependence of ULF wave power matches observations, the diffusion coefficient maximizes for 90° pitch angles. This suggests that simulations of relativistic electron dynamics in the equatorial plane can serve as an upper limit in modeling flux or phase space density evolution.
Description	xiv, 144 leaves : ill. (some col.) 28 cm.
Format	application/pdf
Advisor	Mary K. Hudson.
Subject	Van Allen radiation belts -- Mathematical models. Electrons -- Diffusion -- Mathematical models. Magnetohydrodynamic waves -- Mathematical models.
College	Dartmouth College -- Department of Physics and Astronomy.
Issuing Body	Dartmouth Dissertations are made available through the Dartmouth Digital Library.
Degree	Thesis (Ph.D.)--Dartmouth College.
Copyright	All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means without permission in writing from the author.
DOI	http://dx.doi.org/10.1349/ddlp.43

Title	Page 1
Format	application/pdf
Issuing Body	Dartmouth Dissertations are made available through the Dartmouth Digital Library.
Degree	Thesis (Ph.D.)--Dartmouth College.
Full Text	Radial Diffusion of Radiation Belt Electrons in Three Dimensions A Thesis Submitted to the Faculty in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physics and Astronomy by Kara Lynn Perry DARTMOUTH COLLEGE Hanover, New Hampshire December 2004 Examining Committee: Prof. Mary K. Hudson (chair) Prof. John G. Lyon Prof. James W. LaBelle Dr. Scot Elkington Charles K. Barlowe Dean of Graduate Studies

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