Date of Award

5-17-2024

Document Type

Dissertation

Abstract

We study obstacles to plasma flow in an ion kinetic regime. That is, plasma on a scale where ion gyromotion is relevant, but elections may be treated collectively as a fluid. Specifically, we study continuous mass loading of a stream of plasma (or equivalently, a continuous injection of mass into an ambient plasma) using global hybrid and test particle simulations to bolster our understanding of experimental data. First we characterize the Kinetic-Scale Energy and Momentum Transport Experiment (KiNET-X) and evaluate momentum coupling between an injected plasma cloud and the ambient ionospheric plasma. We found evidence of non-ideal coupling mechanisms but could not optically confirm that the ion cloud skidded across magnetic field lines because uncertainties in the ionization process obscure the physical motion of the ion cloud. Then we analyze data from the New Horizons flyby of Pluto using similar methods. Pluto's escaping atmosphere produces and ionized obstacle to the solar wind. the data from the thermal plasma instrument, Solar Wind Around Pluto (SWAP), showed a broad heavy ion wake. We were able to show that the width of the heavy ion tail is controlled by magnetic pressure and is therefore sensitive to the upstream interplanetary magnetic field (IMF). We infer an IMF around 0.1 nT based on this data. However, New Horizons' energetic particle instrument, Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI), found a steep decrease in energetic particle intensity in Pluto's wake. The simplest way to explain this result would be a higher IMF around 0.3 nT. We explore several possible explanations that could resolve this conflict. We find that the initial result is more reliable and, most likely, the IMF was near 0.1 nT. Future simulations may resolve the discrepancy.

Handle

http://hdl.handle.net/11122/15129

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