Laser ablation ignition of flammable gas

To reduce the minimum pulse energy required for laser ignition (MPE), thereby reducing the cost of the laser device and realizing multipoint ignition with the same laser energy, the ignition mechanism flammable gas using laser ablation was investigated by varying the distance between the target and the focusing lens, together with schlieren and direct color emission observation, which reveals the behavior of the ablative target material and initial flame kernel. It was found that the MPE in the ablative ignition was consistent with the ablation threshold energy of laser fluence on the target, except when the laser focal point was near the target surface. In this latter case, vortex flow induced by laser breakdown and successive collision of the initial flame kernel with the target was observed. The increase in MPE, in this case, was explained by heat loss in the initial flame kernel.