Dissertation/Thesis Abstract

Study of the femtosecond dynamics and spectroscopy of laser ionized plasmas
by Elle, Jennifer Anne, Ph.D., University of Maryland, College Park, 2015, 115; 3711220
Abstract (Summary)

Ultra-short laser pulses are used to ionize gas in different configurations and study the plasma and ionization dynamics. The variation in non-linear index of refraction as a function of time is used to diagnose laser-plasma interactions. First, a proposed novel method to stimulate lasing in the atmosphere is studied. A few mJ pulse is used to ionize nitrogen gas in a long column without dissociating the molecular nitrogen. A 140ps laser is used to heat the resulting electron population in an attempt to generate a population inversion between the C3Πu and B 3Πg states of molecular nitrogen. No evidence of lasing from this transition is observed. Next, a few mJ pulse is used to ionize xenon gas, creating Xe+ plasma. Ionization in Xe+ is observed far below the threshold predicted by multiphoton ionization theory due to resonant multiphoton ionization of collisionally excited states. To my knowledge, this is the first observation of resonant ionization involving multiple resonances. Finally, construction of an experiment to detect predicted birefringence in a relativistic laser-plasma interaction is described, with preliminary testing of diagnostics included.

Indexing (document details)
Advisor: Milchberg, Howard M.
Commitee: HIll III, Wendell T., Kim, Ki-Yong, Sprangle, Phillip, Wahlstrand, Jared
School: University of Maryland, College Park
Department: Physics
School Location: United States -- Maryland
Source: DAI-B 76/11(E), Dissertation Abstracts International
Subjects: Optics
Keywords: Birefringence, Interferometry, Ionization, Laser, Plasma
Publication Number: 3711220
ISBN: 978-1-321-87323-8
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