激光蒸汽羽的光楔错位干涉诊断

DIAGNOSIS OF LASER INDUCED VAPOR PLUME WITH A PLANO-PLATE SHEARING INTERFEROMETER

本文介绍了光楔错位干涉与高速摄影相结合诊断1.06μm长脉冲与靶相互作用产生蒸汽羽等离子体的方法。在平面铝靶厚度1mm,激光脉宽约1ms,平均功率密度约1.2×10~7W/cm^2条件下,首次拍摄了激光与靶耦合产生蒸汽羽等离子体的干涉分幅照片。根据干涉分幅照片,在距离凝聚态靶面不同的截面上,给出了蒸汽羽折射率随径向距离的变化曲线,并得到相应的电子密度约为10^(18)cm^(-3),温度约为4500K的结果。它们都随径向、轴向距离的增加而减少。

The vapor plume produced by a focused normal mode pulsed neodymium glass laser beam (1.06μm, 1ms) on an aluminum plate (1mm) in air at average power densities up to 107W/cm2 has been studied by a piano-plate shearing interferometer with a high speed photograph. The frame interference photograph of the vapor plume was obtained. At the different sections, the refractive index curves are derived. Based on the vapor plume refractive index, the electron density is deduced to be about 1018cm-3, and the temperature about 4,500K and both of them decrease radially and axially.