基于快速ICCD照相、纹影照相及发射光谱法的激光诱导等离子体特性(英文)

Pulsed laser produced plasmas(LPP)are important for industrial applications and fundamental researches,and their complex,multi-physical and cross-chemical processes need to be investigated more comprehensively.In this work,images of the luminous plasma,the spatial density distribution,and the plasma parameters are experimentally investigated by using fast ICCD photography,schlieren photography,and optical emission spectroscopy.Plasmas are produced by a 1 064 nm,15 ns Nd:YAG laser.Free expanding and splitting phenomena are observed in vacuum(at the pressure of about 1×10 3Pa)and air(at the pressure of 20 Pa)using fast photography,respectively.Meanwhile,shock waves formed in the atmospheric laser produced plasma are visualized by schlieren photography.The formation of shock waves is interpreted with the Sedov-Taylor theory,and an averaged expansion velocity about 375 m/s of the shock waves is estimated during 200～1 000 ns.Atmospheric air is found to have significant confinement effects on the plasma expansions compared to that in vacuum or low pressure ambient.Based on the optical emission spectroscopy,after 1 000 ns,at 0.6 mm above the target,the plasma temperature is about 7 800 K and the electron number density is approximately 0.64×1016cm-3.