双脉冲激光诱导铝等离子体的双波长干涉诊断

双脉冲激光诱导等离子体在激光加工、元素检测、材料去除等领域有广阔的应用前景和发展空间，对其进行诊断具有重要意义。针对延迟双脉冲激光诱导铝等离子体的作用效果和影响机理，采用双波长干涉法对其时间演化规律展开研究。基于马赫-曾德尔干涉仪搭建了双波长干涉诊断系统，得到了双脉冲激光诱导等离子体干涉图。通过对干涉图的处理和分析，得到了等离子体电子密度随双脉冲激光延迟时间的变化规律。结果表明，随着双脉冲激光延迟时间的增加，第二束脉冲激光对等离子体电子密度的增强效果先加强后减弱。其中，双脉冲激光延迟时间为10 ns时，对等离子体电子密度的增强效果最强，在30 ns时刻，其中心区域平均电子密度可达6.49×1019 cm?3，相较于同等能量单脉冲激光诱导等离子体提升了26%。同时研究了延迟时间对第二束脉冲激光作用机制的影响。研究结果为双脉冲激光诱导等离子体的优化方向提供了参考。

Dual-wavelength interferometric diagnosis of double-pulse laser induced aluminium plasma

Double-pulse laser-induced plasma has broad application prospects and development space in laser processing, detection of element, material removal and other fields, so it is of great significance to diagnose it. The time evolution law of plasma was obtained by two-wavelength interferometry, to study the effect and mechanism of plasma induced by delayed double-pulse laser. A dual-wavelength interference diagnosis system based on the Mach-Zehnder interferometer was established. It had ability to acquire interferogram of the double-pulse laser-induced plasma. By processing and analyzing the interferogram, the evolution law of plasma electron density with the delay time of double-pulse laser was obtained. The result shows that the effect of the second pulse laser on the plasma electron density first enhances and then weakens with the prolongation of the delay time between double-pulse laser. Among them, when the delay time of the double-pulse laser is 10 ns, the enhancement effect on the plasma electron density is the strongest, when 30 ns, the average electron density in the central region can reach 6.49×1019 cm?3, which is 26% higher than that of single-pulse laser-induced plasma with the same energy. Meanwhile, the effect of delay time on the mechanism of secondary pulse laser was studied. The research results provide a reference for the optimization direction of double-pulse laser-induced plasma.