纳秒激光诱导紫铜黄铜等离子体特征参数的对比研究

基于1064 nm Nd:YAG激光器，对比研究了紫铜和黄铜等离子的特征参数。洛仑兹函数拟合Cu I 324.75 nm得到紫铜和黄铜等离子体的电子密度分别是3.61017 cm-3和3.31017 cm-3。为了减小谱线自发辐射跃迁几率不确定性和测量误差带来的计算误差，采用改进型迭代玻耳兹曼算法精确求解紫铜等离子体和黄铜等离子体的电子温度分别是6316 K和6051 K，分析表明，两种等离子体特征参数的差异主要是由于黄铜中的锌元素的电离能（9.39 eV）大于铜元素的电离能（7.72 eV）而造成的。实验数据证实激光诱导的紫铜和黄铜等离子体满足局部热力学平衡模型和光学薄模型。

Comparison of copper and brass plasma parameters produced by nanosecond laser-ablation

The fundamental harmonic of a pulsed Nd:YAG laser (1064 nm) was used for the ablation of copper and brass samples in air at atmospheric pressure and the laser-induced plasma characteristics were examined comparatively. The electron densities N_e of 3.6×10¹⁷ cm^-3 in copper plasma and 3.3×10¹⁷ cm^-3 in brass plasma were inferred from the Stark broadened profile of Cu I 324.75 nm averaged with 15 single spectra. In order to minimize relative errors in calculation of the electron temperature T_e, an improved iterative Boltzmann plot method was used. Experimental results showed that the electron temperature in copper plasma was 6316 K larger than the value (6051 K) in brass plasma because the ionization potential of Zn (9.39 eV) is higher than that of Cu (7.72 eV). The plasma was verified to be in local thermodynamic equilibrium (LTE) and optical thin state based on the experimental results.