Date of Award

3-2025

Document Type

Thesis

Degree Name

Master of Science in Applied Physics

Department

Department of Engineering Physics

Second Advisor

Seth H. Garland, PhD

Abstract

Solar flares are intense bursts of electromagnetic radiation, which occur due to a rapid destabilization and reconnection of the magnetic field. While flares are a magnetic phenomena, very little attention has been paid to thermal conditions in the corona prior to flare onset. This study serves as a follow-on to Kniezewski et al., 2024, where the EUV emission from coronal loops was observed to vary substantially and without any coherence between channels before 53 off-limb flares. These variations suggest multiple mechanisms within the coronal magnetic field are responsible for heating fluctuations. Here, the 3D magnetic field is modeled using a Non-Linear Force Free Field extrapolation for 6 hours before and 1 hour after 18 on-disk solar flares and during flare quiet windows for each active region. Parameters are calculated directly from the magnetic field from two field isolation methods: the "Active Region Field," which isolates field lines where the photospheric field magnitude is > 200 Gauss, and the "High Current Region," which isolates field lines in the 3D field where the current, non-potential field, twist, and shear exceed thresholds. There is significant increase in variation starting 2-4 hours before flare onset for the current, twist, shear, and free energy, and the variation continues to increase through the flare start time. The current, twist, shear, and free energy are also significantly stronger through the lower corona, and their separation from flare quiet height curves scales with flare strength. Connections between pre-flare magnetic field variations and quiescent coronal loop thermal changes are discussed, with emphasis on potential heating sources. Methods are proposed to combine pre-flare coronal EUV emissions and magnetic fields, suggesting a new potential flare prediction capability.

AFIT Designator

AFIT-ENP-MS-25-M-220

DTIC Accession Number

AD1356287

Comments

An embargo was observed for posting this graduate work on AFIT Scholar. 

Approved for public release, distribution unlimited. PA case number 88ABW-2025-0189

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