Date of Award
Master of Science in Applied Physics
Department of Engineering Physics
Robert D. Loper, PhD
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).
DTIC Accession Number
Round, Joseph F., "Variations of Heavy Ion Abundances Relative to Proton Abundances in Large Solar Energetic Particle Events" (2019). Theses and Dissertations. 2207.