The Experimental Study Of Tiny Impulse Coupling Characteristics During Laser Ablation In Different Media

High energy impulse laser irradiation of solid metal target can make the target get a certain momentum. Under different environmental conditions, by researching the impulse coupling coefficient of laser, the dynamic properties of laser’s reacting on materials can be analyzed which is important to the laser ablation.In this article, the impulse coupling coefficient of laser’s reacting on aluminum target is separately studied in air and liquid. Firstly, the interaction between laser and target under different conditions was theoretically studied in this paper, and then the shock wave model in gas and liquid was analyzed. Then the impulse coupling coefficient of aluminum target was measured. The measurement of this experiment is by using piezoelectric sensor which was designed dependently with the material of aluminum. Experiments were undertook separately in both gas and liquid. In a gas environment, the research content are as follows:(1)Under the standard air pressure, the relationship between laser energy density and the impulse coupling coefficient of aluminum target was researched;(2) Changing air pressure, the impulse coupling coefficient of aluminum target was measured under the same energy density, then the effect of air pressure on the aluminum target’s ablation was studied;(3)When the laser energy density was changed, the effects on the radius of ablation aluminum target was studied. In the liquid, the main researches include as follows:(4)The relationship between laser energy density and the impulse coupling coefficient of aluminum target was researched under a certain layer thickness of water;(5)The influence of laser focus position in the water on the impulse coupling coefficient of aluminum target was studied;(6)The effect of different liquid’s characteristics on the impulse coupling coefficient of aluminum target was analyzed.The experiment results show that: When the ablation of aluminum target occurs under the condition of gas, the ablation rate and the laser plasma shock wave pressure may have influence on the impulse coupling coefficient of aluminum target in different laser energy density, at the same time, the ablation threshold would affect the value of the impulse coupling coefficient. When ablation of aluminum is in liquid, the trend of laser ablation variation under different energy density is closed to the trend in gas, but the value of the impulse coupling coefficient in liquid is greatly higher than in the air. It was found that the farther focus distance from target surface, the smaller value of the impulse coupling coefficient in liquid, and the result may vary differently before target and behind target. At last the experiment also found that the density and the ionization degree of liquid may influence the result. When the density and the ionization degree of liquid is big, the value of the impulse coupling coefficient is big.