title: New diagnostic methods for laser plasma- and microwave-enhanced combustion.
abstract: The study of pulsed laser- and microwave-induced plasma interactions with atmospheric and higher pressure combusting gases requires rapid diagnostic methods that are capable of determining the mechanisms by which these interactions are taking place. New rapid diagnostics are presented here extending the capabilities of Rayleigh and Thomson scattering and resonance-enhanced multi-photon ionization (REMPI) detection and introducing femtosecond laser-induced velocity and temperature profile imaging. Spectrally filtered Rayleigh scattering provides a method for the planar imaging of temperature fields for constant pressure interactions and line imaging of velocity, temperature and density profiles. Depolarization of Rayleigh scattering provides a measure of the dissociation fraction, and multi-wavelength line imaging enables the separation of Thomson scattering from Rayleigh scattering. Radar REMPI takes advantage of high-frequency microwave scattering from the region of laser-selected species ionization to extend REMPI to atmospheric pressures and implement it as a stand-off detection method for atomic and molecular species in combusting environments. Femtosecond laser electronic excitation tagging (FLEET) generates highly excited molecular species and dissociation through the focal zone of the laser. The prompt fluorescence from excited molecular species yields temperature profiles, and the delayed fluorescence from recombining atomic fragments yields velocity profiles.
authors.affiliation: Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Sciences, Princeton University, Olden Street, Princeton, NJ 08544, USA miles@princeton.edu.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Miles
authors.affiliation: Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Sciences, Princeton University, Olden Street, Princeton, NJ 08544, USA.
authors.forename: James B
authors.initials: JB
authors.lastname: Michael
authors.affiliation: Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Sciences, Princeton University, Olden Street, Princeton, NJ 08544, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Limbach
authors.affiliation: Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Sciences, Princeton University, Olden Street, Princeton, NJ 08544, USA.
authors.forename: Sean D
authors.initials: SD
authors.lastname: McGuire
authors.affiliation: Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Sciences, Princeton University, Olden Street, Princeton, NJ 08544, USA.
authors.forename: Tat Loon
authors.initials: TL
authors.lastname: Chng
authors.affiliation: Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Sciences, Princeton University, Olden Street, Princeton, NJ 08544, USA.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Edwards
authors.affiliation: Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Sciences, Princeton University, Olden Street, Princeton, NJ 08544, USA.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: DeLuca
authors.affiliation: Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Sciences, Princeton University, Olden Street, Princeton, NJ 08544, USA.
authors.forename: Mikhail N
authors.initials: MN
authors.lastname: Shneider
authors.affiliation: Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Sciences, Princeton University, Olden Street, Princeton, NJ 08544, USA.
authors.forename: Arthur
authors.initials: A
authors.lastname: Dogariu
keywords: Thomson scattering; depolarized Rayleigh scattering; femtosecond laser electronic excitation
  tagging; filtered Rayleigh scattering; radar resonance-enhanced multi-photon ionization