Date of Award

3-22-2019

Document Type

Thesis

Degree Name

Master of Science in Applied Physics

Department

Department of Engineering Physics

First Advisor

Robert D. Loper, PhD

Abstract

Past studies of heavy ions (Z>2) in large (E>10 MeV/nuc) gradual solar energetic particle (SEP) events have focused on elemental abundances relative to those of a single element, such as Fe or O, and have often neglected ionized H (the primary element used for space weather purposes). This work analyzes SEP abundances in a group of 15 large gradual SEP events from 2000 to 2015 across the energy range of 13.5-50.7 MeV. Hourly flux averages of He, C, O, Mg and Fe from the Advanced Composition Explorer/Solar Isotope Spectrometer (ACE/SIS) are compared to two-hour averages of H flux from the Solar and Heliospheric Observatory/Energetic and Relativistic Nuclei and Electron (SOHO/ERNE) experiment. Event-to-event comparisons reveal order of magnitude variances in all elements studied (with Fe exhibiting variances spanning several orders of magnitude). A strong correlation is seen between abundance enhancement relative to the spectral coronal and linear coronal mass ejection (CME) speeds for He, C, O and Mg. Extreme Fe abundance events are determined to have energy loss rates equal to those of H (the consequences of which are briefly discussed).

AFIT Designator

AFIT-ENP-MS-19-M-090

DTIC Accession Number

AD1078203

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