Possibility of initiation of combustion of CH$_4$–O$_2$ (air) mixtures with laser-induced excitation of O$_2$ molecules

The possibility of initiation of combustion of CH$_4$–O$_2$ mixtures with excitation of O$_2$ molecules to the states $a^1\Delta_g$ and $b^1\Sigma^+_g$ by laser radiation with wavelengths of 1.268 $\mu$m and 762 nm is considered. It is shown that excitation of O$_2$ molecules significantly decreases the induction period and ignition temperature because of accelerated formation of active atoms and radicals and intensification of the chain mechanism of the process. Even if the specific energy of laser radiation absorbed by the gas is low ($\approx$0.1 eV per molecule), the ignition temperature of the CH$_4$–O$_2$ mixture with a ratio of 1:2 can be reduced from 1000 to 300 K.