Laser ignition of engines

Laser ignition of engines represents a more and more realistic alternative to traditional spark plug or high-frequency ignition approaches. Its ability to ignite extremely lean mixtures of fuel and air allows one to efficiently reduce the NO x concentrations in the exhaust gases, which are associated with potential long-lived ignition components. In this paper, an overview of the laser parameters necessary to ignite the most common methane-hydrogen-air mixtures for gas engines is presented. Furthermore, a novel approach for multipoint laser ignition is discussed as a viable path for speeding up the long combustion durations of lean mixtures. Finally, an innovative approach to compact, robust, and relatively cheap laser ignition is described, which involves miniature laser systems. The passively Q-switched laser head is ideally mounted on each cylinder, while the optical pump should be located far away. Ignition energies in the range of slightly more than 1 mJ per pulse are realized with the involvement of perfect optical focusing.