利用啁啾脉冲频谱干涉技术研究高应变率载荷下铜膜的动态响应特性  

Experiment research on dynamic response of copper film at high strain rate by chirped pulse spectral interferometry

作　　者：范伟[1] 朱斌[1] 席涛[1] 李纲[1] 卢峰[1] 吴玉迟[1] 韩丹[1] 谷渝秋[1] 

机构地区：[1]中国工程物理研究院激光聚变研究中心,等离子体物理重点实验室,绵阳621900

出　　处：《物理学报》2016年第15期33-38,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11405159);中物院科学技术发展基金(批准号:2014A0102003)资助的课题~~

摘　　要：啁啾脉冲频谱干涉测量技术具有高时间分辨的连续测量能力,属于一种单发超快诊断技术.本文利用25 fs的激光脉冲对厚度为502 nm的金属铜膜进行冲击加载,同时利用啁啾脉冲频谱干涉仪开展超快诊断,在单发次实验内测量获得了皮秒时间分辨的铜膜自由面启动过程,并由此得到自由面的启动时刻和速度剖面上升前沿宽度6.9 ps.根据冲击波关系式,冲击波在材料中引起的冲击压强和应变率分别为(57.1±8.8)GPa,8×109 s^(-1).That the femtosecond laser pulses irradiate metallic materials thereby inducing ultrahigh strain rates,is an important experimental approach to studying the material behavior under extreme conditions.Femtosecond laser-generated shock waves in metal films have rise times of several picoseconds,the corresponding diagnostic technique is required to work with a higher time resolution,which makes the experimental measurements difficult.Chirped pulse spectral interferometry（CPSI） possesses capabilities of ultrafast time resolution and continuous measurement,thus it provides a diagnostic technique for studying the ultrashort shock wave.In this article,we carry out an experiment on femtosecond laser driven shock wave in copper film and the measurement by CPSI.Laser pulse of 25 fs duration at the central wavelength800 nm is used,the tested samples are copper films of（502 ± 5） nm in thickness fabricated by electron beam sputtering deposition onto cover slip substrate of 180 μm in thickness,pump beam focuses onto front surface of the copper film through the transparent substrate and this laser intensity is 2.3 x 10^13 W/cm^2.Chirped pulse spectral interferometry is used to detect the movements of the free rear surfaces of the copper films with temporal and spatial resolution.In the spectral interferometry,linearly chirped pulse is required and obtained by stretching the femtosecond laser pulse with a pair of gratings.The relation between frequency and time of the chirped pulse is accurately measured using asymmetric spectral interference method,which is required for explaining the experimental data.Since CPSI is a single shot diagnostic technique,we obtain the displacement and velocity history of the free rear surface with picosecond time resolution in a single measurement.From the results,the average shock velocity is calculated to be（5.6 ± 0.2） km/s and the shock wave rise time is determined to be 6.9 ps.According to the shock wave relations,impact pressure and strain rate in the copper film are（57.1 ± 8

关 键 词：啁啾脉冲 频谱干涉 时间分辨 冲击波 

分 类 号：O436.1[机械工程—光学工程]