【作者】 张正荣；

【导师】 袁萍；

【作者基本信息】 西北师范大学 ， 原子与分子物理， 2007， 硕士

【摘要】 通过测定无外加电场和有外加电场两种情况下的激光诱导Al等离子体空间分辨发射光谱,得到了发射光谱强度和谱线展宽的演化特性,并由此研究了电子密度随空间距离和外加电压的变化规律。此外,还探讨了激光脉冲能量的变化对发射光谱强度和谱线展宽的影响。主要内容有:(1)激光诱导Al等离子体的电子密度用Nd:YAG脉冲激光器产生的1.06μm激光,在低压环境下烧蚀金属Al靶,获得等离子体,并观测其空间分辨发射光谱;利用AlⅠ的两条发射谱线的Stark展宽计算了Al等离子体电子密度,分析了电子密度随空间的演化规律。结果发现:在靶面附近电子密度达到最大值,随着离靶面距离的增加,电子密度逐渐减小,从微观物理机制的分析推断:激光诱导等离子体的复合辐射是电子密度减少的主要原因。另外,还探讨了激光能量的变化对等离子体电子密度的影响。(2)外加电场对激光诱导Al等离子体发射光谱的影响在低压环境下,用Nd:YAG脉冲激光器产生的1.06μm激光烧蚀金属Al靶获得等离子体,观测了在外加电场下其空间分辨发射光谱,并由此分析了谱线强度、谱线展宽随外加电压的变化情况。结果发现:原子谱线强度及展宽均随外加电压的增大明显增大,而离子谱线受外加电压的影响较小。分析推断:外加电场使非稳态等离子体中的电子作定向运动,加剧电子与原子之间的碰撞是上述结果的主要原因。此外,还讨论了外加电场对等离子体中电子密度的影响。更多还原

【Abstract】 The evolution properties of spectral broadness and spectral intensities are obtained by measuring Al space-resolved emission spectra with or without additional electricity field. As a result, the electron densities of plasma in different spatial distances and in various additional voltages are studied. Furthermore, the influence of power density to the spectral broadness and the spectral intensities are discussed. The main content includes:(1) The electron density of laser induced Al plasmas.By using 1.06μm pulse laser produced by Nd:YAG laser ablation, the space resolved emission spectra were gotten under low air pressure. The electron density of Al plasma was calculated by measuring the Stark broadness of line. The spatial distribution of electron density was studied. It reaches its highest value near the target surface, and reduces with the distance increasing from target surface. Recombination radiation is considered to be the primary reason for the reducing electron density, and to a certain extent the experiment result is to be explained by it. The effects of laser pulse energy on the electron density were studied as well.(2) Emission spectroscopic studies of Laser-induced Al Plasma in additional electric field.The emission spectrum of Al plasma produced by ablating Al target with Q-switch Nd:YAG Laser(wavelength 1.06μm, pulse width 10 ns) is observed under a low air pressure and direct electricity field. The intensity and the broadness of spectral line in various additional voltages are measured, the result of which shows that the intensity and the broadness of spectral line of Al atom are increasing prominently with the additional voltage increasing, but there is little influence on both intensity and broadness of ion spectral line. The collision between atoms and electrons moving in a definite direction with the additional static electric field is considered to be the primary reason for the result mentioned above. In addition, the effects of the additional voltage on the electron density are also discussed.更多还原