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实验中,长脉冲激光作用下的薄膜破坏常伴随着等离子体闪光,该闪光是等离子体在向外空间膨胀消耗能量时所发出的弧光。从高密度等离子体液滴膨胀过程的运动学、动力学、热力学过程出发,分析了等离子体液滴膨胀过程中的液滴半径、电子加热速率、电子密度、电子温度、离子温度等随时间演化的情况。分析认为等离子体膨胀引起的电子密度变化会影响其对激光能量的吸收速率,从而影响电子、离子温度,进而影响等离子体膨胀速度。这些影响也必将延伸到等离子体对薄膜表面的冲击压力中去,对薄膜激光损伤过程的后期分析具有重要的意义。
In the experiment, the destruction of the thin film under the action of the long-pulse laser is often accompanied by the plasma flash, which is the arc emitted by the plasma when it is dissipated in the outward space. Based on the kinematics, dynamics and thermodynamics of the high-density plasma droplet expansion, the evolution of the droplet diameter, the electron heating rate, the electron density, the electron temperature and the ion temperature during plasma droplet evolution were analyzed . The analysis shows that the change of electron density caused by the plasma expansion will affect the rate of laser energy absorption, which will affect the electron and ion temperature, and then affect the plasma expansion rate. These influences will also extend to the impact pressure of the plasma on the film surface, which is of great significance to the post-analysis of the thin-film laser damage process.