激光诱导液相基质等离子体电子温度的时间演化特性研究

通过单脉冲激光烧蚀MgSO4水溶液射流产生激光等离子体,通过调节ICCD门脉冲相对激光脉冲的延时,测定了液相基质中激光等离子体中Mg元素的时间分辨发射光谱.实验结果表明,当ICCD门延时在0.6μs-1.6μs范围内变化时,谱线强度随延时的增大逐渐减小,但减小的速度越来越慢;谱线的信噪比有一个先上升后缓慢减小并趋于稳定的过程.同时,利用Boltzmann斜线法对Mg原子谱线(518.36nm,517.268nm,516.732nm,383.829nm,383.230nm,382.935nm)进行拟合,得到了不同延时下Mg等离子体的电子温度范围为4772K-6281K,线性相关系数为0.958.拟合结果说明本实验条件下得到的液相基质激光等离子体满足局部热平衡条件.

An Experiment Investigation on the Temporal Evolution Characteristics of Laser-Induced Plasma of the Liquid Sample

The laser induced plasma of MgSO4 solution were produced by single pulse laser ablation of the liquid jets.The time resolved emission spectra of Mg atom in the liquid solution were measured by changing the ICCD gate delay relative to the laser pulse.It was shown that the spectral line intensity decreased and the decay ratio became slowly along with the increase of the ICCD gate delay in the range from 0.6μs to 1.6μs.The signal to noise ration increased with the increase of the gate delay firstly and then decreased slowly and finally became to a fixed value.Meanwhile,the electron temperature of the plasma determined by the Boltzmann approach by the measured 518.36nm,517.268nm,516.732nm,383.829nm,383.23nm,382.935nm spectral line intensities of Mg atom were varied from 6281K to 4772K at different gate delay.The fitted line correlation factor 0.958 demonstrated that laser induced plasma produced by this experiment satisfied the local thermal equilibrium approximation.