Characteristics of Laser Produced Plasmas Obtained by Fast ICCD Photography, Schlieren Photography and Optical Emission Spectroscopy  

作　　者：WEI Wenfu WU Jian LI Xingwen JIA Shenli QIU Aici 

机构地区：[1]State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi'an 710049, China

出　　处：《高电压技术》2013年第9期2173-2179,共7页High Voltage Engineering

基　　金：Project supported by National Natural Science Foundation of China（51237006）.

摘　　要：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.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 pho- tography, 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 ~ 10-3 Pa） and air（at the pressure of 20 Pa） using fast photography, respec- tively. 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 esti- mated 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 tem- perature is about 7 800 K and the electron number density is approximately 0.64×10^16 cm^-3.

关 键 词：等离子体密度 发射光谱仪 纹影摄影 激光产生 ICCD 生产 特性 等离子体参数 

分 类 号：TL631.24[核科学技术—核技术及应用] TH744.11[机械工程—光学工程]