Date of Award

Spring 2022

Project Type

Dissertation

Program or Major

Physics

Degree Name

Doctor of Philosophy

First Advisor

Roy Torbert

Second Advisor

Charles Farrugia

Third Advisor

Kai Germaschewski

Abstract

During the process of magnetic reconnection, anti-parallel magnetic fields with embedded plasma particles converge and undergo a dramatic topological reconfiguration in the electron diffusion region (EDR) while releasing some of the stored magnetic energy directly into the particles. This process is ubiquitous in natural plasmas, and is responsible for many of the explosive phenomena observed in the Earth's magnetosphere and on the sun. While it has long been established that magnetic reconnection is a plasma energization process, it is still unclear what mechanisms underlie the energy conversion from fields to particles, particularly in the EDR where magnetohydrodynamic (MHD) approximations are invalid. The aim of this thesis is to examine these small-scale energization processes of reconnection using combination of in-situ Magnetospheric Multiscale (MMS) data, Particle-in-Cell (PIC) simulations of reconnection, and test particle tracing techniques. First, the spatial and temporal evolution of reconnection is studied from an energy balance perspective by evaluating the terms in Poynting's theorem in MMS data and PIC simulations. Second, the physics of the outer EDR are examined, with particular focus on the development and effect of localized 'generator' regions where the plasma returns some of its energy back to the electromagnetic fields. Third, the electron kinetic structure of the EDR is analyzed in detail and illustrated with particle tracing techniques. The results suggest that the central EDR is characterized by an approximately time-independent balance of Poynting's theorem, whereas near the outer EDR, there is much more time-dependent dissipation as accelerated electron populations begin to remagnetize and mitigate the growth of the reconnection structures.

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