Towards Multiplexed Fiber Delivered Laser Ignition for Natural Gas Engines

The use of laser ignition for advanced gas engines may provide benefits including extension of the lean limit and higher efficiency operation at elevated pressures. This contribution provides a short review of efforts to develop a practical laser ignition system for advanced multicylinder gas engines. The approach is to use a single laser source with fiber optic cables delivering the high power pulses from the source to the engine cylinders. The optical requirements for the fiber delivery lead us to use coated hollow core optical fibers. Characterizations and results of spark delivery tests for the fibers are presented. Single-cylinder engine test results using fiber delivered laser ignition are summarized. For multicylinder operation, a multiplexer based on a moving mirror is used to route the laser output pulses to different fiber channels (cylinders). Benchtop testing and initial engine testing of the multiplexed system are presented.