【作者】 赵书瑞；

【导师】 陈金忠；

【作者基本信息】 河北大学 ， 光学， 2003， 硕士

【摘要】 激光诱导等离子体的过程是一个相当复杂的过程，它与许多因素密切相关。本文采用高能量钕玻璃激光器，研究了激光器工作电压、功率密度、等离子体的观测高度、样品位置、环境气体及气压对等离子体的谱线强度及谱线质量的影响，获得了最佳的实验条件，并测量了金属分析样品中某些元素的含量。结果表明：等离子体的谱线强度随激光器工作电压、功率密度的增大而增大。(1)对于光谱标钢准样品，当激光器工作电压为1600V、氩气压力为600乇时，谱线强度达到最大，并且在相同压强下，氩气中的等离子体与空气中的等离子体相比，其辐射强度明显增强；氩气压力为320乇时的谱线信背比约为600乇条件下的5倍，而等离子体温度却下降了近1000K，即等离子体温度随环境气压的增大而增大；当激光束的焦斑在样品表面上下移动时，激光诱导量、等离子体的激发温度、谱线强度都呈不对称性分布，其最大值对应的焦斑位置都位于样品表面之下0.4mm左右。(2)对于标准铝样品，在激光器工作电压为1600V、等离子体观测高度为2mm、氩气压力为660乇时，其谱线强度最强；以Al Ⅰ 308.22nm、Al Ⅰ 309.27nm两条谱线为分析线，发现随着环境气压的增大，谱线自吸效应明显增强，当环境气压达到600-700乇时，谱线几乎产生自蚀。 作为激光诱导等离子体技术的应用，对于光谱标钢样品6-3中的Mn、Ni、Ti元素进行定量分析，其分析精密度(RSD)分别为：5.949％、4.779％、5.214％，元素含量相对误差在10.7％范围内；对715号标样铝中Zn元素的分析结果为：RSD为3.749％，元素含量相对误差位于8.2％范围内。结果表明元素含量与谱线强度之间有良好的线性关系。更多还原

【Abstract】 Laser induced -plasma is a very complex process. It strongly depends on many factors. In this experiment , a neodymium glass laser is used to study the effects of the operating voltage, power density, the height from the observed location of the plasma to the surface of the sample, the location of the sample, the gas composition and the pressure on the intensity and quality of the spectrum. The optimized experimental conditions are determined and the densities of some elements in the mental alloy standard samples are measured .The experimental results shows that the spectral intensity of the plasma enhances significantly with the increase of the operating voltage and the power density.(1) To the steel ally sample, the emission intensities of the spectra reach to the maximum values when the laser operating voltage is 1600V and the argon pressure is 600 torr. Under the same pressure, the spectral intensity of the plasma in the argon atmosphere is stronger than that in the air. When the argon pressure is 320 torr, the signal-noise ration is about 5 times than that which the argon pressure is 700 torr, but the temperature of plasma is less about 1000k. That is to say, the temperature increase with the increase of the atmospheric pressure. If the focal point of the len shifts around the surface of the sample, the mass ablation, the temperature of the plasma and the spectral intensity appear asymmetric and their maximum occur at the location which is about 0.4mm under the surface of the sample. (2) To the plasma of the aluminum alloy sample, when the operating voltage is 1600V,the height from the observed location of the plasma to the surface of the sample is 2mm and the argon pressure is 660 torr, the spectral intensity have the maximum values. The self-absorption ability of the Al(I)308.22nm and A(I)309.27nmlines is strengthen with the increase of increase of the pressure, and even appear self-reversal when the pressure is 600-700 torr.As the use of the laser induced-plasma , we determine the densities of the Mn, Ni, Ti elements in the 6-3 steel alloy standard sample and the Zn element in the 715 aluminum alloy, The Relative Standard Deviation(RSD) are respectively 5.949%,4.779%,5.214%,3.749%.and the relative errors are lower than 10.7%. Thisshows there is a good linear relation between the spectral intensity and the elemental density.更多还原