Plasma and Beam Physics Commons^™

Behavior Of Magnetic Reconnection In The Relativistic Regime Under The Presence Of Shear Flows And Guide Field, Sarah Peery

Dartmouth College Ph.D Dissertations

Magnetic Reconnection is a ubiquitous phenomenon in plasma, where magnetic energy is released into plasma thermal and kinetic energy through the rearrangement of magnetic topology. In this study we derive fluid scaling models to predict the steady state and onset behavior of magnetic reconnection in the highly magnetized (relativistic) regime, in the presence of plasma shear flows and a (out-of-plane) guide field. We use 2.5D kinetic particle-in-cell simulations to motivate and validate these models. We find that, similar to the non-relativistic regime, shear flows parallel to the reconnecting magnetic field will delay reconnection onset and slow outflow jets. They can …

Modeling Velocity Distributions Of Interstellar Neutral Hydrogen In The Heliosphere, Lucas Robert Dyke

Dartmouth College Ph.D Dissertations

As interstellar neutral hydrogen (ISN H) is the most abundant neutral element in the helio- sphere, the region within which the solar wind interacts with the portion of the interstellar medium through which our solar system moves through, it is integral that we aim to under- stand its many properties and interactions within this region. This work details the synthesis and use of a model of ISN H, using trajectory methods to backtrace from a target point at a radial distance of 1 au where explorer probes like Interstellar Boundary Explorer (IBEX) and Interstellar Mapping and Acceleration Probe (IMAP) reside. …

In Situ Observations Of Thermal Ions In Perturbed Ionospheres: Techniques And Results, Magdalina Louise Moses

Dartmouth College Ph.D Dissertations

Prediction and mitigation of space weather events are active research topics that require knowledge of the physics governing the ionosphere. Sounding rockets can be used to make in situ observations. The Lynch Rocket Lab created the Petite-Ion-Probe (PIP), a small retarding potential analyzer, to measure thermal ion parameters (i.e., ion density and temperature). A PIP's raw data consists of a series of measured anode currents as a function of screen bias voltages, called IV curves. PIPs can be integrated onto a sounding rocket’s main payload and/or be deployed from the rocket on small platforms called ``PIP-Bobs''. Note that as the …

Magnetic Reconnection In Space: From Two-Dimensional Magnetohydrodynamic (Mhd) Simulations To Three-Dimensional Particle-In-Cell (Pic) Simulations, Shan-Chang Lin

Dartmouth College Ph.D Dissertations

Magnetic reconnection is a physical process in plasmas that converts magnetic energy into plasma kinetic energy and thermal energy. It plays an important role in the generation of solar flares, interactions between the solar wind and Earth's magnetosphere, and magnetic confinement fusion devices. This thesis focuses on studying magnetic reconnection using computational methods, including two-dimensional (2D) magnetohydrodynamics (MHD) simulations to study Petschek-type reconnection, estimating the timescale from a thin current sheet to fully developed reconnection using 2D particle-in-cell (PIC) simulations, and magnetic reconnection X-line spreading in the current direction using three-dimensional (3D) PIC simulations.

This thesis contributes to the understanding …

Current Continuity In Auroral System Science, Jules Van Irsel

Dartmouth College Ph.D Dissertations

The Earth relies on the Sun's energy, but at times this energy can be overwhelming; the Sun expels plasma which, were it not for our humble magnetic field, would erode our atmosphere (Mars, c. 4 Ga). The protective interaction Earth has with the solar wind results in spectacular auroral displays---one such auroral form is discussed in this thesis: quiet discrete auroral arcs.

Such arcs have long been studied; they are abundant, have usable symmetries, and they can predict magnetic substorms that wreak havoc in our magnetosphere. The auroral emissions, albeit beautiful, are however only the visible end of a self-consistent …