A5018590061- Spectroscopy and Laser Applications
- Laser Design and Applications
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Laser-induced spectroscopy and plasma
- Combustion and flame dynamics
- Combustion and Detonation Processes
- Gas Dynamics and Kinetic Theory
- Energetic Materials and Combustion
- Earthquake Detection and Analysis
- Advanced Chemical Physics Studies
- Advanced Combustion Engine Technologies
- Various Chemistry Research Topics
- Rocket and propulsion systems research
- Atomic and Subatomic Physics Research
- Chemical Thermodynamics and Molecular Structure
- Atmospheric chemistry and aerosols
- Plasma and Flow Control in Aerodynamics
- Advanced Fiber Laser Technologies
- Molecular spectroscopy and chirality
- Computational Fluid Dynamics and Aerodynamics
- Plasma Applications and Diagnostics
- Diamond and Carbon-based Materials Research
- Crystallography and Radiation Phenomena
- Advanced Sensor Technologies Research
Purdue University West Lafayette
2016-2025
Stanford University
2011-2016
Temper (United States)
2013-2016
The development and initial demonstration of a scanned-wavelength, first-harmonic-normalized, wavelength-modulation spectroscopy with nf detection (scanned-WMS-nf/1f) strategy for calibration-free measurements gas conditions are presented. In this technique, the nominal wavelength modulated tunable diode laser (TDL) is scanned over an absorption transition to measure corresponding scanned-WMS-nf/1f spectrum. Gas then inferred from least-squares fitting simulated spectrum measured spectrum,...
A novel strategy has been developed for analysis of wavelength-scanned, wavelength modulation spectroscopy (WMS) with tunable diode lasers (TDLs). The method simulates WMS signals to compare measurements determine gas properties (e.g., temperature, pressure and concentration the absorbing species). Injection-current-tuned TDLs have simultaneous intensity variation, which severely complicates Fourier expansion simulated signal into harmonics frequency (fm). new differs from previous...
The design and use of two-color tunable diode laser (TDL) absorption sensors for measurements temperature H2O in a rotating detonation engine (RDE) are presented. Both used first-harmonic-normalized scanned-wavelength-modulation spectroscopy with second-harmonic detection (scanned-WMS-2f/1f) to account non-absorbing transmission losses emission encountered the harsh combustion environment. One sensor two near-infrared (NIR) TDLs near 1391.7 nm 1469.3 that were modulated at 225 kHz 285 kHz,...
In this work, laser absorption spectroscopy techniques are expanded in spatial resolution capability by utilizing a high-speed infrared camera to image flow fields backlit with tunable mid-wave radiation. The imaging (LAI) method yields spectrally-resolved and spatially-rich datasets from which quantitative species temperature profiles can be generated using tomographic reconstruction. Access the (3-5 µm) enables of fuels, intermediates, products combustion canonical small-diameter flames (<...
Coherent anti-Stokes Raman scattering (CARS) and nitric oxide molecular tagging velocimetry (NO-MTV) are used to characterize the freestream in Sandia's Hypersonic Shock Tunnel (HST) using a burst-mode laser operated at 100-kHz. Experiments performed nominal velocities of 3 4 km/s both air N2 test gas. The CARS diagnostic provides nonequilibrium characterization flow by measuring vibrational rotational temperatures O2, which compared NO from separate absorption experiments. Simultaneous,...
A tunable quantum cascade laser sensor, based on wavelength modulation absorption spectroscopy near 4.8 μm, was developed to measure CO concentration in harsh, high-pressure combustion gases. The sensor employs a normalized second harmonic detection technique (WMS-2f/1f) at frequency of 50 kHz. Wavelength selection 2059.91 cm⁻¹ targets the P(20) transition within fundamental vibrational band CO, chosen for strength and relative isolation from infrared water carbon dioxide absorption....
A two-color absorption spectroscopy strategy has been developed for measuring the column density and density-weighted path-average temperature of absorbing species in nonuniform gases. This uses two transitions with strengths that scale nearly linearly temperature. In addition, measured lineshapes are used to accurately model absorbance spectra. As a result, can be inferred from comparison signals across line sight (LOS) simulated calculated using uniform LOS. is demonstrated simulations...
The development, validation and demonstration of a two-color tunable diode laser (TDL) absorption sensor for measurements temperature H2O in high-pressure high-temperature gases are presented. This uses first-harmonic-normalized wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f/1f) to account non-absorbing transmission losses emission encountered harsh, environments. Two telecommunications-grade TDLs were used probe transitions near 1391.7 1469.3 nm. lasers...
A tunable diode laser absorption sensor near 2.7 µm, based on 1f-normalized wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f), was developed to measure CO2 concentration in harsh combustion flows. Wavelength selection at 3733.48 cm−1 exploited the overlap of two transitions ν1 + ν3 vibrational band 3733.468 and 3733.498 cm−1. Primary factors influencing wavelength were isolation strength lines relative infrared water elevated pressures temperatures. The HITEMP 2010...