不同气流环境下氟化氘激光对45~#钢靶的辐照效应

45# steel interaction with DF laser beam in different gas flow

通过表面形貌观察、温度场分析,研究了切向空气气流、切向氮气气流、自然对流3种环境下氟化氘(DF)激光对45#钢靶的辐照效应,结果表明:切向空气气流环境下,钢靶烧蚀效果最显著,靶板后表面中心温升最高;切向氮气气流环境下,钢靶有一定的烧蚀,但温升最低;自然对流环境下,烧蚀效果最差。实验结果表明:切向气流可移除部分熔化物,特别在切向空气气流环境下剧烈的氧化反应可促进钢靶温度升高,显著增强激光对钢靶的烧蚀,停止激光辐照后切向气流的冷却效应起主要作用。根据实际物理问题建立了相应的数值计算模型,模拟了不同气流环境下激光对钢靶的辐照效应,其中,利用"生死单元"的方法,模拟了切向空气气流环境下激光对钢靶的烧蚀,并考虑了氧化放热的影响。模拟结果与实验结果基本相符,解释了气流在激光辐照效应中的作用。

Experimental measurement was employed to study the effects of the DF high-power laser irradiation on 45#steel in different gas flow.The surface picture was analyzed and the temperature histories were measured.The effect of steel ablation was obvious and the temperature on the rear center of the coupon was highest in the tangential air flow.The experimental results showed that some melt was removed by the tangential gas flow,especially in the air flow where combustion played an important role in heating the material.The target was cooled after laser irradiation.According to the experimental results,a numerical model was established to simulate the irradiation effects of high power density laser on steel targets in different gas flow.The method of Element birth and death was employed to simulate the ablation effects of laser on steel targets in the air flow,where the effects of heat releasing by oxidation were included.The results of the numerical simulation agreed well with the experimental results.It explained the effects of the gas flow in the laser irradiation.