1D interferometric Rayleigh scattering velocimetry and thermometry using VIPA.

The work introduces a VIPA-based interferometric Rayleigh scattering instrument for tracer-free, simultaneous temperature and velocity measurements along a 1D volume. A virtually imaged phased array (VIPA) replaces the Fabry-Perot etalon conventionally used in interferometric Rayleigh scattering, allowing the extension of the technique from 0D (point or multi-point) to 1D. The Rayleigh-Brillouin spectrum is a function of pressure and temperature and can be used for temperature diagnostics in isobaric flows.

Pressure dependence in aqueous-based electrochemical CO reduction.

Electrochemical CO reduction (COR) is an approach to closing the carbon cycle for chemical synthesis. To date, the field has focused on the electrolysis of ambient pressure CO. However, industrial CO is pressurized-in capture, transport and storage-and is often in dissolved form.

Fiber-bundle-based 2D Raman and Rayleigh imaging for major species and temperature measurement in laminar flames.

In this Letter, we introduce a novel fiber-bundle-based 2D Raman and Rayleigh imaging system for 2D measurements of major species mole fractions and temperature in flames. A cascade of dichroic mirrors and bandpass filters separate the Raman signal associated with each major species and direct it to a custom-built four-inputs/one-output fiber bundle. The single output of the fiber bundle allows simultaneous detection of four species by using a single back-illuminated CCD camera.

Temperature dependent Raman spectra of ammonia ranging from 3150 cm to 3810 cm for combustion applications.

Applying in combustion research, Raman scattering technique can provide high accuracy and high precision measurements of temperature and major species concentrations. However detailed knowledge of the temperature dependent Raman spectra of the probed species is a precondition to realise the potential of high precision and accuracy of the technique. As a carbon free novel fuel, the knowledge of high temperature Raman spectra of ammonia is rarely reported.

One-dimensional interferometric Rayleigh scattering velocimetry using a virtually imaged phased array.

One-dimensional interferometric Rayleigh scattering velocimetry is demonstrated using a virtually imaged phased array (VIPA). A continuous-wave laser emitting at 532 nm is used as the source, and a low-noise CCD camera is used as the detector. The VIPA has a free spectral range of 15 GHz and is coated for the wavelength range 500-600 nm.

High-speed 1D Raman analyzer for temperature and major species measurements in a combustion environment.

In this Letter, we demonstrate a 5 kHz 1D Raman instrument for temporally and spatially resolved quantitative measurements of temperature and all the major species (, , , and ) concentration in -air flames. The major constituents of the system are a pulse-burst laser operated at 5 kHz and four back-illuminated CCD cameras operated in subframe burst-gating mode. The use of CCD cameras allows achieving a high sampling rate with no compromise on instrument precision, but it requires one camera for each species of interest.

Tracer-free laser-induced grating spectroscopy using a pulse burst laser at 100 kHz.

This work shows the first application of a burst laser for laser-induced grating spectroscopy (LIGS) diagnostics. High repetition rate (100 kHz) LIGS is performed in non reacting and reacting flows using the fundamental harmonic of a Nd:YAG pulse-burst laser as pump. In the first part of the paper, we demonstrate the first time-resolved, high repetition rate electrostrictive LIGS measurements in a sinusoidally-modulated helium jet, allowed by the highly energetic pulses delivered by the burst laser (around 130 mJ per pulse).

Mole fraction measurement through a transparent quarl burner using filtered Rayleigh scattering.

A filtered Rayleigh scattering system is developed and applied to measure the mole fraction of methane in a methane-air swirl flow through a transparent conical quartz quarl. Light scattering from the location where the laser beam is incident on the surface of the quarl is orders of magnitudes larger than Rayleigh scattering from the gas mixture of interest. This diffusive scattering is suppressed using molecular absorption by an iodine cell and using spatial filtering by an optical aperture.

High-speed Rayleigh-Raman measurements with subframe burst gating.

A 10-kHz one-dimensional Rayleigh-CH Raman instrument capable of achieving highly precise measurement of temperature and methane mole fraction is demonstrated. The system uses a pulse-burst laser as the light source and back-illuminated electron-multiplied CCD cameras as the detectors. The cameras are operated in the subframe burst gating mode, to combine a high sampling rate, low noise, and a slow readout.

Development of a dual-pump coherent anti-Stokes Raman spectroscopy system for measurements in supersonic combustion.

This work describes the development of a dual-pump coherent anti-Stokes Raman spectroscopy system for simultaneous measurements of the temperature and the absolute mole fraction of N2, O2, and H2 in supersonic combusting flows. Changes to the experimental setup and the data analysis to improve the quality of the measurements in this turbulent, high-temperature reacting flow are described. The accuracy and precision of the instrument have been determined using data collected in a Hencken burner flame.

Beam shaping for CARS measurements in turbulent environments.

This paper describes a new technique to mitigate the effect of beam steering on CARS measurements in turbulent, variable density environments. The new approach combines planar BOXCARS phase-matching with elliptical shaping of one of the beams to generate a signal robust to beam steering, while keeping the same spatial resolution. Numerical and experimental results are provided to demonstrate the effectiveness of this approach.