Shadowgraph investigation of plasma shock wave evolution from Al target under 355-nm laser ablation  

作　　者：刘天航 郝作强 高勋 刘泽昊 林景全 

机构地区：[1]Changchun University of Science and Technology

出　　处：《Chinese Physics B》2014年第8期408-414,共7页中国物理B（英文版）

基　　金：Project supported by the National Key Basic Research Program,China(Grant No.2013CB922404);the National Natural Science Foundation of China(Grant Nos.61178022,11074027,11274053,and 11211120156);the Funds from Science and Technology Department of Jilin Province,China(Grant Nos.20111812 and 20130522149JH);the Research Fund for the Doctoral Program of Higher Education of China(Grant Nos.20122216120009,20122216110007,and 20112216120006)

摘　　要：The propagation of a plasma shock wave generated from an Al target surface ablated by a nanosecond Nd：YAG laser operating at 355 nm in air is investigated at the different focusing positions of the laser beam by using a time-resolved shadowgraph imaging technique. The results show that in the case of a target surface set at the off-focus position, the condition of the focal point behind or in front of the target surface greatly influences the evolution of an Al plasma shock wave, and an ionization channel forms in the case of the focal point set in front of the target surface. Moreover, it is found that the shadowgraph with the evolution time around 100 ns shows that a protrusion appears at the front tip of the shock wave if the focal point is at the target surface. In addition, the calculated results of the expanding velocity of the shock wave front, the mass density, and pressure just behind the shock wave front are presented based on the shadowgraphs.The propagation of a plasma shock wave generated from an Al target surface ablated by a nanosecond Nd：YAG laser operating at 355 nm in air is investigated at the different focusing positions of the laser beam by using a time-resolved shadowgraph imaging technique. The results show that in the case of a target surface set at the off-focus position, the condition of the focal point behind or in front of the target surface greatly influences the evolution of an Al plasma shock wave, and an ionization channel forms in the case of the focal point set in front of the target surface. Moreover, it is found that the shadowgraph with the evolution time around 100 ns shows that a protrusion appears at the front tip of the shock wave if the focal point is at the target surface. In addition, the calculated results of the expanding velocity of the shock wave front, the mass density, and pressure just behind the shock wave front are presented based on the shadowgraphs.

关 键 词：laser-induced plasma shock wave air ionization off-focus 

分 类 号：O53[理学—等离子体物理]