Advanced laser spectroscopy in combustion chemistry: From elementary stepsto practical devices

In recent years a large number of linear and nonlinear laser-based diagnost ic techniques for nonintrusive measurements of species concentrations, temp eratures, and gas velocities in a wide pressure and temperature range with high temporal and spatial resolution have been developed and have become ex tremely valuable tools to study many aspects of combustion. Beside the noni ntrusive diagnostics of technical combustion devices the kinetics and micro scopic dynamics of elementary chemical combustion reactions can be investig ated in great detail by laser spectroscopy. These investigations show, that a small number of relatively simple elementary steps like H + O-2 --> OH O, H2O2 --> 2OH, O + N-2 --> NO + N, NH2 + NO --> H2O + N-2, OH + N2H cont rol a large variety of combustion phenomena and pollutant formation process es. Laminar flames are ideal objects to develop the application of laser sp ectroscopic methods for practical combustion systems and to test and improv e the gas-phase reaction mechanism in combustion models. Nonintrusive laser point and field measurements are of basic importance in the validation and further development of turbulent combustion models. Nonlinear laser spectr oscopic techniques using infrared-visible sum-frequency generation can now bridge the pressure and materials gap to provide kinetic data for catalytic combustion. Finally, the potential of laser techniques for active combusti on control in municipal waste incinerators is illustrated.