脉冲CO2激光诱导空气等离子体的光谱诊断

为了了解激光诱导等离子体的演化过程,得到等离子体的相关参量,采用横向激励大气压CO2激光器在抛物反射面中聚焦击穿空气形成等离子体,利用成像光谱仪和增强型CCD探测器对激光诱导等离子体进行了时间和空间分辨的实验分析,取得了激光诱导空气等离子体的时间演化和空间分辨光谱。分别利用氧原子的线状谱和连续谱的比值及谱线半峰全宽计算得到电子温度达到了4104K,电子密度在1018cm-3量级。结果表明,相比于低能量的激光诱导等离子体的辐射光谱,高能量激光诱导的等离子体则向外辐射出很强的连续光谱,同时,等离子体以激光支持爆轰波的形式快速向外膨胀,由于外围等离子体对激光能量的屏蔽作用,等离子体出现了空间分离的现象。该研究结果对理解等离子体和高能量脉冲激光的相互作用过程是有帮助的。

Spectroscopic diagnosis of air plasma induced by pulsed CO2 laser

In order to study the evolution of laser-induced plasma and obtain the properties of plasma, transversely excited atmospheric CO2 laser was focused by a parabolic reflector to generate air breakdown plasma. Based on the imaging spectrometer system and intensified CCD detector, time-space resolution of laser-induced air plasma were investigated and the time evolution spectra and the space resolution spectra of plasma were obtained. Electron temperature of about 4104K and electron density of 1018cm-3 were calculated respectively by using the ratio of oxygen line spectrum and continuous spectrum and full width at half maximum of spectral line. The results show high-energy laser-induced plasma spectra radiate the intense continuous spectra outward, comparing with low-energy laser-induced plasma spectra. At the same time, laser-induced air plasma expands outward rapidly with the way of the laser-supported detonation wave. Due to the shielding effect of laser power, laser-induced air plasma shows the behavior of spatial separation. The results are useful for understanding the interaction between plasma and high-energy laser.