Theses and Dissertations from UMD

Permanent URI for this communityhttp://hdl.handle.net/1903/2

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

Browse

Filters

20191

Settings

Author: search.filters.author.Isaacs, Joshua J

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    THE PHYSICS OF HIGH-INTENSITY LASER-MATTER INTERACTIONS AND APPLICATIONS
    (2019) Isaacs, Joshua J; Sprangle, Phillip; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This dissertation consists of three separate research topics: First, the effect of laser noise on the propagation of high-power and high-intensity short pulse lasers in dispersive and nonlinear media is studied. We consider the coupling of laser intensity noise and phase noise to the spatial and temporal evolution of laser radiation. We show that laser noise can have important effects on the propagation of high-power as well as high-intensity lasers in a dispersive and nonlinear medium such as air. We present atmospheric propagation examples of the spatial and temporal evolution of intensity and frequency fluctuations due to noise for laser wavelengths of 0.85 μm, 1 μm, and 10.6 μm. Next, a concept for all-optical remote detection of radioactive materials is presented and analyzed. The presence of excess radioactivity increases the level of negative ions in the surrounding air region. This can act as a source of seed electrons for a laser-induced avalanche ionization breakdown process. We model irradiated air to estimate the density of negative ions and use a set of coupled rate equations to simulate a subsequent laser-induced avalanche ionization. We find that ion-seeded avalanche breakdown can be a viable signature for the detection of radioactivity, a conclusion which has been experimentally tested and verified. Finally, we propose and analyze a mechanism to accelerate protons from close to rest in a laser-excited plasma wave. The beating of two counter-propagating laser pulses in a plasma shock-excites a slow forward-propagating wakefield. The trapping and acceleration of protons is accomplished by tapering both the plasma density and the amplitude of the backward-propagating pulse. We present an example in which protons are accelerated from 10 keV to 10 MeV in a distance of approximately 1 cm.