【摘要】：聚焦的高能激光和固體金屬鋁靶作用,通過燒蝕固體靶產(chǎn)生等離子體,使靶材料獲得一定動量。在不同的環(huán)境條件下,通過實驗研究激光燒蝕沖量耦合系數(shù),可以分析激光和材料作用的動力學(xué)性質(zhì),對于激光燒蝕研究有重要意義。本文分別在氣體介質(zhì)和液體介質(zhì)中研究激光燒蝕鋁靶材料的沖量耦合系數(shù)。首先從理論上研究了不同環(huán)境下激光和靶材作用,對空氣和液體中沖擊波行為進(jìn)行模型分析。接著實驗測量不同條件下的激光燒蝕鋁靶沖量耦合系數(shù)。實驗測量方法為壓電傳感器測量,傳感器為自主設(shè)計的鋁質(zhì)探頭。實驗分別在氣體環(huán)境和液體環(huán)境兩種不同條件下進(jìn)行。在氣體環(huán)境下,研究內(nèi)容有:(1)研究標(biāo)準(zhǔn)氣壓下鋁靶沖量耦合系數(shù)和激光能量密度關(guān)系;(2)改變氣壓,測量相同能量密度下激光沖量耦合系數(shù),研究氣壓對燒蝕鋁靶的影響;(3)改變激光能量密度、研究激光能量密度對燒蝕鋁靶面半徑的影響。在液體環(huán)境條件下,主要研究內(nèi)容有:(4)水層厚度一定時,研究激光能量密度對鋁靶沖量耦合系數(shù)的影響;(5)研究激光在液體中聚焦位置對鋁靶沖量耦合系數(shù)的影響;(6)變換不同的液體介質(zhì),研究液體介質(zhì)性質(zhì)對鋁靶沖量耦合系數(shù)影響。實驗結(jié)果表明:激光在氣體環(huán)境中燒蝕鋁靶時,隨著激光能量密度的改變,鋁靶沖量耦合系數(shù)大小會受到激光燒蝕鋁靶的速率及等離子沖擊波壓強的影響,并且當(dāng)激光存在燒蝕閾值時會影響沖量耦合系數(shù)的大小。激光在液體環(huán)境中燒蝕鋁靶,鋁靶沖量耦合系數(shù)隨激光能量密度的變化趨勢和空氣中近似,但是液體環(huán)境中激光沖量耦合系數(shù)要明顯高于空氣中。實驗發(fā)現(xiàn)在液體水柱中,激光聚焦位置距離靶面越遠(yuǎn),鋁靶沖量耦合系數(shù)越小,同時靶前靶后聚焦效果不同。最后實驗還發(fā)現(xiàn),在一定條件下,密度大的液體介質(zhì)沖量耦合系數(shù)大,并且沖量耦合系數(shù)還和電離程度的難易有關(guān)。
[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.
【學(xué)位授予單位】：河南師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN249

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