Skip to content
University of Maryland LibrariesDigital Repository at the University of Maryland
    • Login
    View Item 
    •   DRUM
    • Theses and Dissertations from UMD
    • UMD Theses and Dissertations
    • View Item
    •   DRUM
    • Theses and Dissertations from UMD
    • UMD Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    PHYSICS AND APPLICATIONS OF EXTENDED AIR HEATING BY FEMTOSECOND LASER FILAMENTATION

    Thumbnail
    View/Open
    Larkin_umd_0117E_22698.pdf (4.039Mb)
    No. of downloads: 94

    Date
    2022
    Author
    Larkin, Ilia
    Advisor
    Milchberg, Howard M
    DRUM DOI
    https://doi.org/10.13016/6a7g-hvtp
    Metadata
    Show full item record
    Abstract
    Femtosecond laser pulses of sufficient energy can propagate as filaments in air due to a dynamic interplay between nonlinear self-focusing and ionization-induced defocusing. A filament in air is characterized by a narrow, 100 m diameter core propagating at high intensity for many Rayleigh ranges corresponding to the core diameter, surrounded by a lower intensity reservoir that exchanges optical energy with the core. The high intensity core ionizes the air and excites molecular rotational wavepackets in N2 and O2. Thermal relaxation of these excitations leads to air heating over very long and narrow volumes, launching acoustic waves and imprinting density profiles in air. These features enable longitudinal mapping of energy absorption, interaction with aerosols in air, guiding of high voltage discharges, and the generation of long air waveguides for subsequent laser pulses. All of these topics are detailed in this dissertation.In particular, we present: (1) Single shot axially resolved energy deposition measurements, using a synchronized array of microphones, to see on a shot-by-shot basis the effect of air turbulence on nonlinear pulse propagation. (2) Measurements of the pre-breakdown evolution of a laser triggered high voltage spark gap, induced by a density channel imprinted by femtosecond laser pulses. By interferometrically measuring air heating and current leakage through the spark gap we clarify the role of laser plasma vs laser air heating in triggering breakdowns. (3) Air waveguiding experiments extended to ranges up to 50 m from the original ~1 m experiments. (4) Fog droplet clearing experiments showing that in natural filamentation of a collimated beam, direct optical interactions are the dominant clearing mechanism rather than acoustic effects.
    URI
    http://hdl.handle.net/1903/29275
    Collections
    • Physics Theses and Dissertations
    • UMD Theses and Dissertations

    DRUM is brought to you by the University of Maryland Libraries
    University of Maryland, College Park, MD 20742-7011 (301)314-1328.
    Please send us your comments.
    Web Accessibility
     

     

    Browse

    All of DRUMCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    LoginRegister
    Pages
    About DRUMAbout Download Statistics

    DRUM is brought to you by the University of Maryland Libraries
    University of Maryland, College Park, MD 20742-7011 (301)314-1328.
    Please send us your comments.
    Web Accessibility