Abstract
• Laser ignition of a CH 4 /air mixture using fs laser filament ablation is proposed. • Ignition of lean fuel with ultralow MPE at 1 mJ and 100% success rate is achieved. • Successful ignition is no longer sensitive to the ablator position. • Reliable Ignition with little amount sample removal of 80 ng/pulse is showed. • This approach is straightforwardly extendable to a designed remote distance. Laser ablation ignition is an efficient approach in igniting lean-fuels with significantly reduced minimum pulse energy (MPE), but it requires a precise position control between the laser focal spot and the target surface, and is hardly for long-term use due to laser-induced surface damage. Here we adopt femtosecond filamentating laser to ablate a tantalum target for igniting a premixed methane-air mixture, and demonstrate the experimental realization of lean-fuel ignition over 1-m distance with 100 % success rate and ultralow MPE at ∼1 mJ. We further show that this technique is insensitive to the ablator position and can operate at a durable time with a little amount (∼80 ng/pulse) of sample removal from the target surface. By characterizing the evolution of flame kernel using time-resolved spectroscopy, we clarify the ultralow MPE ignition mechanism, in which the exothermal chemical reactions occurring inside the plasma filament effectively extends the kernel reaction zone, resulting in a plasma-channel-assisted ablation ignition.
Published Version
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