本研究探討雷射鑽孔製程中雷射加熱基材所產生之蒸氣煙塵，對雷射光源能量造成衰減之效應，與對鑽孔孔洞形貌之影響。在雷射鑽孔製程中，基材被雷射光源加熱後，材料會被汽化並噴出基材表面而形成蒸氣煙塵；從基材表面噴出之蒸氣煙塵會逐漸冷卻並凝結成核成煙塵粒子，散佈在基材表面上方的煙塵粒子會對雷射光源產生散射效應，造成最後作用在基材表面上的雷射能量衰減。
本研究建構一物理模型，模擬奈秒(ns)等級之雷射脈衝對基材的加熱與溫升、產生之蒸氣煙塵的動態變化、粒子凝結成核與最終對雷射光源造成的散射效應等物理現象。數值計算結果指出，增加雷射功率密度，會縮短雷射光源對基材表面的有效作用時間，但會增強雷射對基材表面的材料移除率與總移除量。
實驗上利用脈衝時間為毫秒(ms)等級之Nd:YAG脈衝雷射，對石墨靶材進行鑽孔實驗，並觀察雷射光源強度對時間之變化。實驗觀察結果顯示，延長雷射的脈衝時間雖然會增加雷射脈衝的單發能量，但雷射的平均能量強度卻是呈下降趨勢。
模擬結果與實驗結果顯示，模擬之平均移除率，與實驗之平均鑽孔率，皆會隨著雷射能量密度的增加而下降，兩者趨勢具有一致性。

The effects of the laser induced plume on the energy absorption and hole-shaping in laser drilling have been investigated numerically and experimentally in this study. In the laser drilling process, the substrate material is heated and vaporized by laser beam and the vaporized matters eject from the substrate surface and form the vapor plume. The plume rises from the substrate surface and nucleates as particles after the vapor temperature is decreased. Furthermore the laser beam will be scattered by the plume particles and the absorption of the laser beam on the substrate will decrease.

In the numerical simulation, the physical models include target heating, plume diffusion, particles nucleation and light scattering. The numerical results show that the increase in laser power density will decrease with the effective drilling time but increase the material removal rate in laser drilling.

In the experiment, the graphite target is drilled by a Nd:YAG pulsed laser with various pulse conditions. Furthermore the beam pulse was observed, the results show that the increase of pulse duration time will increase energy of single pulse but decrease the average laser intensity for the present laser system.

Both the numerical and experimental results show that the averaged material remove rate and averaged drilling rate decreases with the increase of the energy density of laser pulse.

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