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为了说明高重复频率脉冲激光材料烧蚀时准真空环境效应的存在,对比不同重复频率的激光脉冲对钢材料的烧蚀率与不同气压环境中的烧蚀率,提出准真空环境效应是平均烧蚀率随脉冲重复频率的提高显著增加的主要原因。将激光脉冲作用形成的准真空环境分为激光等离子体冲击波存在时的准真空环境和激光等离子体冲击波消散后的准真空环境两个时间段,模拟计算和分析了激光作用区周围环境气体密度分布及准真空环境持续时间。实验结果表明,在激光脉冲作用后的几百微秒内,激光烧蚀区周围会存在准真空环境,若后续脉冲在此时间范围内作用于材料,会产生类似于在真空环境中烧蚀的高烧蚀率。
In order to illustrate the existence of quasi-vacuum environment effect when high repetition rate pulsed laser material is ablated, the ablation rate of steel material with different repetition frequency is compared with the ablation rate of different atmospheric pressure environment. It is proposed that the quasi-vacuum environmental effect is average burning The main reason for the significant increase of the etch rate as the pulse repetition frequency increases. The quasi-vacuum environment formed by laser pulse is divided into two stages: the quasi-vacuum environment when the laser plasma shock wave exists and the quasi-vacuum environment after the laser plasma shock wave dissipates. The ambient gas density distribution around the laser action zone is simulated and analyzed And quasi-vacuum environment duration. Experimental results show that within a few hundred microseconds after the laser pulse action, a quasi-vacuum environment exists around the laser ablation zone. If the subsequent pulse acts on the material in this time range, it will have a similar effect to ablation in a vacuum environment High ablation rate.