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利用Nd:YAG脉冲激光在空气中烧蚀金属Cu靶,获得等离子体光谱;采用改变离焦量的方法,研究了离焦量的变化对谱线结构及谱线强度的影响;分析了离焦量分别为1 mm、0 mm和—2 mm时,沿靶面法线方向不同空间距离处电子温度的演化规律;并对等离子体光谱的特性和产生机制进行了讨论.结果表明,谱线结构、谱线强度和等离子体的电子温度都与离焦量的变化密切相关,聚焦点在—2 mm处Cu I谱线相对强度出现峰值,电子温度数值最大;聚焦点在—0.5 mm和—1.0 mm附近谱线相对强度遽然降低的现象是由于等离子体的屏蔽效应造成的.
The Nd: YAG pulsed laser was used to ablate the Cu target in air to obtain the plasma spectrum. The effect of the change of the defocus amount on the line structure and the line intensity was studied by changing the defocus amount. The evolution law of electron temperature at different spatial distances along the normal direction of the target surface at 1 mm, 0 mm and -2 mm respectively. The characteristics and mechanism of the plasma spectra were discussed. The results show that the spectral line structure , The intensity of the line and the electron temperature of the plasma are closely related to the change of the defocusing quantity. The peak of the relative intensity of the Cu I line at the focus point at -2 mm appears, and the electron temperature value is the maximum. The focal point is between -0.5 mm and -1.0 The relative intensity of the spectral lines in the vicinity of mm 遽 decreases due to the shielding effect of the plasma.