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Dissertation
Investigation of ion dynamics and acoustic wave propagation in dipole-confined plasma
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Autumn 2024
DOI: 10.25820/etd.007579
Abstract
Understanding plasma behavior in the dipole magnetic field geometry is important for various naturally-occurring and laboratory plasma environments. Charged particles in this geometry undergo more general particle trajectories than in straight-line magnetic fields, including chaotic orbits. An environment with such general particle motion provides a test-bed for electrostatic wave-scattering experiments in a plasma. Ion acoustic waves are launched far from a permanent dipole magnet and waves mode convert into electrostatic ion cyclotron waves as they approach the magnet. Waves may be reflected, absorbed, or scattered from plasma near a dipole magnet. Laser-induced fluorescence (LIF) techniques provide diagnostic methods for describing ion dynamics in low-temperature plasma as well as the ion response to electrostatic perturbations. In addition to cold and emitting Langmuir probes, LIF measurements are presented for the first time in a dipole magnetic field geometry to characterize the argon ion dynamics as well as ion acoustic wave scattering from dipole-confined plasma.
Details
- Title: Subtitle
- Investigation of ion dynamics and acoustic wave propagation in dipole-confined plasma
- Creators
- Jacob W McLaughlin
- Contributors
- Fred Skiff (Advisor)Gregory Howes (Committee Member)Ravitej Uppu (Committee Member)Albert Ratner (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Physics
- Date degree season
- Autumn 2024
- DOI
- 10.25820/etd.007579
- Publisher
- University of Iowa
- Number of pages
- x, 114 pages
- Copyright
- Copyright 2024 Jacob W McLaughlin
- Language
- English
- Date submitted
- 11/27/2024
- Description illustrations
- illustrations, graphs
- Description bibliographic
- Includes bibliographical references (pages 97-103).
- Public Abstract (ETD)
- Plasma is considered the fourth state of matter which may be described as a fluid made up of positively and negatively charged particles. These particles exhibit collective behavior and are influenced by electric and magnetic fields but overall, the charges cancel out leaving no net electric charge when viewed at large enough length scales. There are various fields in which plasma is very important including the production of semiconductor technologies, energy through nuclear fusion, satellite thrusters, and space physics. In particular, the sun is made up of plasma which may be accelerated towards Earth and threatens our technological infrastructure includ- ing satellites and the electrical grid. Earth’s primary defense to this plasma is its naturally-occurring magnetic field, which may be modeled as a dipole magnet, like that in a bar magnet. Presented in this work are measurements of charged parti- cle behavior in plasma near a dipole magnet and the propagation of waves in this environment. Plasma waves heat and move plasma particles, making them an impor- tant concept to understand. The scattering of radio-frequency waves from plasma in the ionosphere also allows for communication around the globe. There is no general theory for wave-scattering from plasma with particles undergoing general trajecto- ries; however, models are being developed for this very purpose and presented here are experimental measurements which provide data for those models to be compared with.
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984774665202771
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