Laser in situ monitoring of combustion processes

Abstract
Several examples of laser in situ monitoring of combustion processes are presented. Using a frequency modulated 13CO2 waveguide laser, in situ concentrations of NH3 down to 1 ppm were measured at temperatures up to 600°C in waste incinerators and power or chemical plants. Following ignition of CH3OH–O2 mixtures by a TEA CO2 laser, gas temperature profiles were measured using rapid scanning tunable diode laser spectroscopy of CO molecules. In laminar CH4–air counterflow diffusion flames at atmospheric pressure absolute concentrations, temperatures, and collisional lifetimes of OH radicals were determined by 2-D and picosecond LIF and absorption spectroscopy. Two-dimensional LIF and Mie scattering were used to observe fuel injection and combustion in a diesel engine.