2015 Volume 58 Issue 6 Pages 313-318
Laser ablation is expected to achieve the direct initiation of detonation with a smaller amount of energy compared to laser breakdown. In the present work, the critical energy for direct initiation was experimentally studied with an acetylene/oxygen mixture varying the distances between the focal point of the laser beam and the target surface. The observed plasma formation in the laser ablation is divided into three modes: (a) the plasma generated by laser ablation is attached to the target surface; (b) the breakdown plasma partly overlaps with the ablation plasma; and (c) the breakdown plasma is formed separately from the ablation plasma. The dependence of the critical energy for the laser ablation on the distance between the target surface and the focal point is explained by interaction between the breakdown and the ablation plasma. The present results demonstrate that it is possible to initiate detonation directly using laser ablation with much smaller laser energy compared to laser breakdown.
