A5083880712- Combustion and flame dynamics
- Spectroscopy and Laser Applications
- Advanced Combustion Engine Technologies
- Laser-induced spectroscopy and plasma
- Laser Design and Applications
- Spectroscopy Techniques in Biomedical and Chemical Research
- Atmospheric and Environmental Gas Dynamics
- Laser-Matter Interactions and Applications
- Combustion and Detonation Processes
- Atmospheric chemistry and aerosols
- Particle Dynamics in Fluid Flows
- Fire dynamics and safety research
- Mass Spectrometry Techniques and Applications
- Plasma Applications and Diagnostics
- Spectroscopy and Quantum Chemical Studies
- Energetic Materials and Combustion
- Gas Dynamics and Kinetic Theory
- High-Velocity Impact and Material Behavior
- Rocket and propulsion systems research
- Spectroscopy and Chemometric Analyses
- Radiative Heat Transfer Studies
- Fluid Dynamics and Heat Transfer
- Chemical Thermodynamics and Molecular Structure
- Analytical chemistry methods development
- Advanced Fiber Laser Technologies
Texas A&M University
2016-2025
Mitchell Institute
2016-2025
Texas A&M University System
2025
Walker (United States)
2019-2024
Optica
2018-2022
Spectral Energies (United States)
2009-2017
Purdue University West Lafayette
2004-2017
Sandia National Laboratories California
2008-2009
Single-laser-shot temperature measurements at a data rate of 1 kHz employing femtosecond coherent anti-Stokes Raman scattering (fs-CARS) spectroscopy N(2) are demonstrated. The performed using chirped-probe pulse to map the time-dependent frequency-spread dephasing coherence, which is created by approximately 80-fs pump and Stokes beams, into spectrum signal pulse. Temperature determined from spectral shape fs-CARS for probe delays 2 ps with respect pump-Stokes excitation. accuracy precision...
We discuss photolytic-interference-free, high-repetition-rate imaging of reaction intermediates in flames and plasmas using femtosecond (fs) multiphoton excitation. The high peak power fs pulses enables efficient nonlinear excitation, while the low energy nearly eliminates interfering single-photon photodissociation processes. demonstrate proof-of-principle, interference-free, two-photon laser-induced fluorescence line atomic hydrogen hydrocarbon method's implications for certain other...
Femtosecond, two-photon-absorption laser-induced fluorescence (fs-TALIF) is employed to measure space- and time-resolved distributions of atomic hydrogen oxygen in moderate-pressure, non-equilibrium, nanosecond-duration pulsed-discharge plasmas. Temporally spatially resolved TALIF images are obtained over a range low-temperature plasmas mixtures helium argon at 100 Torr total pressure. The high-peak-intensity, low-average-energy fs pulses combined with the increased spectral bandwidth...
We report direct measurement of H2 Q-branch Raman coherence lifetimes using time-resolved picosecond coherent anti-Stokes scattering (ps-CARS). A custom-built, high-peak-power, nearly transform-limited ps laser system offers an ideal combination frequency and temporal resolution for such measurements. The measured pure at room temperature are in good agreement with decay rates that were derived from previous high-resolution studies. Measurements also performed binary mixtures H2–X (X=Ar, N2,...
We report single-laser-shot one-dimensional thermometry in flames using femtosecond coherent anti-Stokes Raman scattering (fs-CARS) line imaging. Fs-CARS enables high-repetition-rate (1-10 kHz), nearly collision-free measurement of temperature and species concentration reacting flows. Two high-power 800 nm beams are used as the pump probe a 983 beam is Stokes for CARS signal generation from N2Q-branch transitions at ∼2330 cm(-1). The frequency-chirped All three laser formed into sheets...
We report the use of femtosecond laser electronic excitation tagging (FLEET) for velocimetry at a 100-kHz imaging rate. Sequential, single-shot, quantitative velocity profiles an underexpanded supersonic nitrogen jet were captured The signal and lifetime characteristics FLEET emission investigated in methane flame above Hencken burner varying equivalence ratios, room temperature gas mixtures involving air, methane, nitrogen. In post-flame region burner, was measured as two orders magnitude...
Metal fuels, such as aluminum (Al) and iron (Fe), can be added to composite solid propellants improve their performance, specific impulse, density, burning rate. In comparison aluminum, theoretically provide improved density impulse higher flame temperatures; reduce condensed combustion product (CCP) concentration the associated two-phase flow losses; eliminate hydrochloric acid (HCl) in exhaust products. A fundamental quantitative understanding of metal particle aggregation agglomeration...
Femtosecond time‐resolved coherent anti‐Stokes Raman scattering (CARS) measurements are performed on neat N 2 and O as well in the presence of various collisional partners to examine effects collisions observed signal at pressures high 50 bar. An exponential‐gap energy‐corrected‐sudden (ECS‐E) scaling law is used model rotational energy transfer pure these elevated pressures. After accounting for line‐mixing effects, long‐time decay (20–60 picoseconds behavior here consistent with previous...
Two-photon laser-induced fluorescence (TP-LIF) line imaging of atomic hydrogen was investigated in a series premixed CH4/O2/N2, H2/O2, and H2/O2/N2 flames using excitation with either picosecond or nanosecond pulsed lasers operating at 205 nm. Radial TP-LIF profiles were measured for range pulse fluences to determine the maximum interference-free signal levels corresponding laser each 12 flames. For an measurement, shape profile is independent fluence. larger fluences, distortions are...
We report direct measurements of S-branch Raman-coherence lifetimes CO(2) resulting from CO(2)-CO(2) and CO(2)-N(2) collisions by employing time-resolved picosecond coherent anti-Stokes Raman scattering spectroscopy. The (ΔJ = +2) transitions with rotational quantum number J 0-52 were simultaneously excited using a broadband (~5 nm) laser pulse full-width-at-half-maximum duration ~115 ps. coherence for pressure range 0.05-1 atm measured directly probing the nearly transform-limited,...