Semester

Fall

Date of Graduation

2022

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Physics and Astronomy

Committee Chair

Earl Scime

Committee Member

Paul Cassak

Committee Member

Amy Keesee

Committee Member

Weichao Tu

Committee Member

Timothy Good

Abstract

Cutting-edge plasma experiments continue to push the frontiers of plasma science. Two such groups of experiments, helicon sources and laboratory magnetic reconnection, are the focus of this thesis. The relatively high plasma density achieved for modest input powers makes helicon source plasmas ideal testbeds for fusion-relevant phenomena without the complexities associated with fusion devices. Examples include plasma-material interaction (PMI) studies, divertor region studies, and boundary physics studies. As advancements in helicon source design and technology make operation at higher power for longer times possible, understanding of the plasma dynamics, particularly ion dynamics, is vital.

Laboratory experiments are essential to advancing the understanding of magnetic reconnection and the associated physics. There is a wonderful synergy between theory, modeling, and simulation efforts and laboratory experiments. Results from these experiments validate and benchmark simulation and theory, while theory and simulation drive the design and goals of experiments. Naturally, this goes the other way as well; interesting results from the laboratory motivate different approaches to theory and simulations. While spacecraft observations of magnetic reconnection have been crucial to the field, laboratory experiments allow for finer control over the parameter space of the magnetic reconnection.

In both of these settings, advanced diagnostics are needed to characterize the physics. Attractive for its non-perturbative nature, laser induced fluorescence (LIF) is well-suited to investigate these plasmas. LIF is used to measure particle velocity distribution functions (VDFs), which in turn reveal fundamental properties of these species such as bulk flow and temperature. In this work, argon ion velocity distribution functions are measured with single-photon LIF. Advancements to the standard LIF technique are presented, and the results obtained with these techniques and their significance are discussed. First, a portable system was developed and deployed to a remote facility where argon ion temperatures in a 10 kW steady-state helicon source were measured. Second, a planar laser induced fluorescence technique with a camera as the detector was developed. Results obtained with this technique are compared with those obtained with the standard technique. Experimental efficiency with the camera technique is an order of magnitude higher than the standard technique at comparable resolution. Finally, a system using a pulsed laser was developed to measure IVDFs during magnetic reconnection. A proof-of-principle measurement with this system is presented.

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