激光诱导击穿空气等离子体参数的光谱分析法

Spectrum analysis on laser-induced air breakdown plasma parameters

空气等离子体的电子温度和密度对激光诱导空气击穿等离子体产生闪光过程的研究有着重要的意义,本文将纳秒Nd∶YAG脉冲激光(1064 nm)聚焦于大气中,诱导其产生等离子体闪光,并通过Avantes-ULS3648型9通道的光谱仪采集闪光光谱,通过光谱分析,研究了不同延迟时间下激光诱导击穿空气等离子体产生过程中的等离子体电子温度和电子密度的变化情况。根据同一元素不同峰值位发出的光谱,由相对强度比较法可以得出等离子体电子温度,由斯塔克展宽法可得到等离子体电子密度的变化,通过分析发现,等离子体电子温度和密度均随延迟时间的增大而下降。这些结果对研究强激光作用下空气击穿的气体动力理论机制有一定的科学意义。

The electron temperature and density of air plasma have important meanings for researching the process of laser-induced air breakdown plasma.A nanosecond Nd∶YAG laser with a wavelength of 1064 nm is used.When the laser is focused on the atmosphere,it will produce a plasma flash.The spectrum of the resulting air breakdown plasma is collected using a Avantes-ULS3648 spectrometer with nine separate channels.The changes of electron temperature and density of the plasma at different delay time are studied by spectral analysis.According to the spectrum of a given element with different peak positions,the electron temperature of the plasma can be obtained by employing the intensity comparative method,and the electron density of the plasma can be obtained by the Stark broadening method.Analysis results show that both the electron temperature and density of the air plasma decrease with the increase of the delay time.This results have a certain scientific significance for aerodynamic theory of air breakdown under high power laser.