Photochemical ignition of premixed hydrogen/oxidizer mixtures with excimer lasers

The initiation of combustion by irradiation of unsensitized fuel-oxidizer mixtures with UV light is investigated both experimentally and analytically. Excimer laser operating at 157 and 193 nm was used to study the wavelength dependence of the photochemical ignition parameters for hydrogen-air and hydrogen-oxygen mixtures. By determining the minimum pressures of ignition of the two mixtures it was found that a fundamental difference exists between conventional spark ignition and the present approach. Overall minima for photochemical initiation occurred at equivalence ratios in the fuel-lean range of 0.6-0.8. Experimental data are noted to agree well with model predictions.