不同介质中激光烧蚀微冲量耦合特性实验研究

发布时间：2018-08-12 09:44

【摘要】：聚焦的高能激光和固体金属铝靶作用,通过烧蚀固体靶产生等离子体,使靶材料获得一定动量。在不同的环境条件下,通过实验研究激光烧蚀冲量耦合系数,可以分析激光和材料作用的动力学性质,对于激光烧蚀研究有重要意义。本文分别在气体介质和液体介质中研究激光烧蚀铝靶材料的冲量耦合系数。首先从理论上研究了不同环境下激光和靶材作用,对空气和液体中冲击波行为进行模型分析。接着实验测量不同条件下的激光烧蚀铝靶冲量耦合系数。实验测量方法为压电传感器测量,传感器为自主设计的铝质探头。实验分别在气体环境和液体环境两种不同条件下进行。在气体环境下,研究内容有:(1)研究标准气压下铝靶冲量耦合系数和激光能量密度关系;(2)改变气压,测量相同能量密度下激光冲量耦合系数,研究气压对烧蚀铝靶的影响;(3)改变激光能量密度、研究激光能量密度对烧蚀铝靶面半径的影响。在液体环境条件下,主要研究内容有:(4)水层厚度一定时,研究激光能量密度对铝靶冲量耦合系数的影响;(5)研究激光在液体中聚焦位置对铝靶冲量耦合系数的影响;(6)变换不同的液体介质,研究液体介质性质对铝靶冲量耦合系数影响。实验结果表明:激光在气体环境中烧蚀铝靶时,随着激光能量密度的改变,铝靶冲量耦合系数大小会受到激光烧蚀铝靶的速率及等离子冲击波压强的影响,并且当激光存在烧蚀阈值时会影响冲量耦合系数的大小。激光在液体环境中烧蚀铝靶,铝靶冲量耦合系数随激光能量密度的变化趋势和空气中近似,但是液体环境中激光冲量耦合系数要明显高于空气中。实验发现在液体水柱中,激光聚焦位置距离靶面越远,铝靶冲量耦合系数越小,同时靶前靶后聚焦效果不同。最后实验还发现,在一定条件下,密度大的液体介质冲量耦合系数大,并且冲量耦合系数还和电离程度的难易有关。
[Abstract]:The focused high energy laser and the solid metal aluminum target produce plasma by ablating the solid target, which makes the target material obtain a certain momentum. Under different environmental conditions, the coupling coefficient of laser ablation impulse can be studied experimentally. The kinetic properties of laser and material interaction can be analyzed, which is of great significance to the study of laser ablation. In this paper, the impulse coupling coefficients of laser ablated aluminum target materials are studied in gas medium and liquid medium, respectively. The effects of laser and target on shock wave behavior in air and liquid were studied theoretically. Then the impulse coupling coefficient of laser ablated aluminum target under different conditions was measured experimentally. The experimental measurement method is piezoelectric sensor, and the sensor is an aluminum probe designed by oneself. The experiment was carried out under two different conditions: gas environment and liquid environment. In the gas environment, the contents of the study are as follows: (1) the relationship between the impulse coupling coefficient and the laser energy density of the aluminum target under the standard pressure; (2) the measurement of the laser impulse coupling coefficient at the same energy density by changing the air pressure; The influence of air pressure on ablative aluminum target is studied. (3) the influence of laser energy density on the radius of ablated aluminum target is studied by changing the laser energy density. Under the condition of liquid environment, the main research contents are as follows: (4) when the thickness of water layer is constant, The effect of laser energy density on the impulse coupling coefficient of aluminum target is studied; (5) the effect of laser focusing position on the impulse coupling coefficient of aluminum target is studied; (6) the effect of liquid medium properties on the impulse coupling coefficient of aluminum target is studied by transforming different liquid media. The experimental results show that with the change of laser energy density, the impulse coupling coefficient of aluminum target is affected by the rate of laser ablation and the pressure of plasma shock wave. And when the laser exists ablation threshold, it will affect the magnitude of impulse coupling coefficient. When the laser ablates the aluminum target in liquid environment, the variation trend of impulse coupling coefficient with laser energy density is similar to that in air, but the coupling coefficient of laser impulse in liquid environment is obviously higher than that in air. It is found that in liquid water column, the longer the laser focusing position is from the target surface, the smaller the impulse coupling coefficient of aluminum target is, and the effect of laser focus on the front target is different. Finally, it is found that under certain conditions, the impulse coupling coefficient of liquid medium with high density is large, and the impulse coupling coefficient is related to the difficulty of ionization degree.
【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN249

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