利用1064 nm Nd:YAG激光器研究了激光诱导铁条等离子体的特征参数.为了减小测量误差和谱线自发辐射跃迁几率不确定性带来的计算误差,采用改进的迭代Boltzmann方法精确求解铁等离子体的电子温度为8058 K.Lorentz函数拟合FeI 376.553 nm得到等离子体的电子数密度为8.7×1017 cm-3.分析表明等离子体的加热机制主要是逆轫致过程,其吸收系数是0.14 cm-1.实验数据证实激光诱导铁等离子体处于局部热力学平衡状态和光学薄状态.%A 1064 nm pulsed Nd:YAG laser is used for the ablation of an iron bar sample in air at atmospheric pressure and the laser-induced plasma characteristics are examined.The electron number density of 8.7 × 1017 cm-3 in the iron plasma is inferred from the Stark broadened profile of Fe 1 376.553 nm averaged with 10 single spectra.In order to minimize relative errors in calculation of the electron temperature,an improved iterative Boltzmann plot method is used.Experimental results show that the electron temperature is 8058 K with a regression coefficient of 0.981 38.Based on the experimental results,the plasma is verified to be in local thermodynamic equilibrium (LTE) and free from self-absorption.Considering the laser photon frequency (2.82 ×1014 Hz) is larger than the plasma frequency (8.3 × 1012 Hz),the loss of energy due to reflection of the laser beam from the plasma can be assumed to be insignificant.Experiments also demonstrate that the inverse Bremsstrahlung (IB) absorption is the dominant photon absorption process during the laser-plasma interaction,and the corresponding IB absorption coefficient is 0.14 cm-1.
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