1813 レーザー着火におけるレーザービームの時間・空間プロファイルの影響(J14-1 環境モニタリングと負荷低減のための熱流体・環境工学の展開(1),J14 環境モニタリングと負荷低減のための熱流体・環境工学の展開)

概要

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Laser-induced breakdown and the ignition were occurred by focusing a 532nm pulse from Q-switched Nd: YAG laser. Methane-air premixture at 1 atm was ignited in a constant volume chamber. In this study, we investigated how the temporal and spatial profile of laser pulse and characteristics of collecting lens have an effect on the breakdown thresholds and the minimum laser pulse energies (MPE) needed for ignition. This measurement result showed that excitation energy of flash lamp changes not only the laser energy but also the temporal and spatial profile of laser pulse. As excitation energy of flash lamp decreases, the laser pulse duration become longer and the spatial profile is getting closer to Gaussian distribution. As a result, MPE depend largely on the temporal and spatial profile of laser pulse. Specifically, as excitation energy of flash lamp decreased, MPE decreased.
2007-09-07