激光等离子体温度时间演化特性

用脉冲CO2激光的10.6 μm光束击穿空气产生等离子体，使用光谱仪和ICCD采集等离子体辐射光谱，在局部热力学平衡近似下，利用相对谱线强度法对激光等离子体温度进行了计算。当激光器单脉冲能量为35 J时，选择NⅡ399.5 nm和NⅡ500.5 nm两条线状谱的相对谱线强度计算了不同延迟时间下等离子体温度。实验结果表明:在等离子体的不同位置，等离子体温度均随时间经历了明显的上升到饱和再到下降的过程，等离子体前沿的温度最先达到饱和，距离靶面最近的位置温度达到饱和所需时间最长。

Temporal evolution of laser plasma temperature

Plasma was produced by laser-induced breakdown in air using the 10.6 μm beam from an pulsed CO2 laser. The plasma spectra were collected by the spectrometer and ICCD. The plasma temperasure was calculated by using the model of local thermodynamic equilibrium. When the laser pulse energy was 35 J, according to the relative intensities of two atom spectral lines NⅡ399.5 nm and NⅡ500.5 nm, the temperature of the plasmas at different time delays was evaluated. It is demonatrated that, the temporal evolution of plasma temperature is ascent-saturation-descent by sampling at the different positions of the plasma, and the temperature at the front edge of the plasma is sooner to become saturated than the temperature near the target.