A novel resonant laser-induced breakdown scheme has been demonstrated to provide precision spatial guidance of spark formation within an air flow and has been further demonstrated successfully in resonant laser-induced ignition of a moderate-speed flow of an air-propane mixture. This scheme could potentially provide ignition within a combustion system with a laser trigger leading to breakdown of an air-fuel flow within a high-voltage gap using a compact low power laser source. The laser scheme involves resonant enhanced multiphoton ionization (REMPI) in molecular oxygen and subsequent laser field-enhanced electron avalanche to generate a pre-ionized micro-plasma path between high voltage electrodes and thus guide the ignition spark through fuel-rich areas of the air-fuel flow. With this resonant method, sufficient photo-ionization and laser field-enhanced electron avalanche ionization have been generated for inducing air breakdown at a relatively low laser power compared to most laser breakdown concepts. This low power requirement may allow for a laser source to be transmitted to an ignition chamber via fiber optic coupling. Results of this study include high speed photographic analyses of flame ignition in an air-propane flow, showing the spatial and temporal evolution of the laser-induced spark and flame kernel leading to combustion.
Physical Sciences and Mathematics | Physics
Adams , S. F. (2013). Laser Induced Ignition with Resonant Multiphoton Absorption in Oxygen. .