脉冲激光-铜靶等离子体产生及其演化过程的瞬态光谱研究

应用时间分辨光谱技术, 研究了高能量纳秒脉冲激光作用下铜靶表面等离子体产生及演化的物理过程. 实验中相互作用区固-气-液三相对激光能量的吸收明显地反映于激光反射强度随时间的演化中, 使得靶表面物质形态的改变导致激光反射强度随时间呈双峰分布.同时, 随着激光峰值功率密度的增加, 靶面等离子体(气)-固-液相变发生的时间相应提前.因此, 这些瞬态性质是诊断激光-固体靶相互作用中靶面物质相变时间的有效方法.

Time-resolved spectrum characteristics of instantaneous plasma generation and evolution processes in nanosecond laser-Cu-target

The physical processes in the generation and the evolution of copper plasma induced by a high power nanosecond laser pulse are investigated with time-resolved spectrum. In the solid-gas-liquid phase transition, the intensity of reflected beam evolving with time markedly reveals the absorption of laser energy in the laser-copper interacting zone. So the phase transitions on the surface of copper target result in the fact that intensity of reflected beam evolving with time obviously presents a double-peak structure. Meanwhile, the appearance times of the plasma-gas-liquid phase transition on the target surface is advanced with the increase of peak-power of laser pulse. Therefore, these transient properties can be an efficient approach to diagnosing the phase transitions of copper target when the laser irradiates the target surface.