Study On Time-Resolved Test Technology Of Damage Dynamics Based On The Hundered-Joule Laser Platform

Fused silica optics is widely used in the terminal optical path of Inertial Confinement Fusion(ICF)laser driver,with high flux ultraviolet laser irradiating on optics,it is easily to format laser-induced damage.Therefore,fused silica optics decides if the ICF system could operate stably and it is the key to improve the load capacity of the ICF laser driver.It is significant to study the mechanism of fused silica's laser-induced damage to instruct an appropriate optical material and components production method,and improve the breakdown threshold.This thesis designs and constructs a time-resolved imaging system with nanosecond time resolution that enables to probe the kinetics of laser-induced damage on fused silica.Firstly,the Pump-Probe experiment system bases on the spatial optical path delay,enables to study the kinetics of laser-induced damage on the inner and exit surface of fused silica by 1064 nm pulsed laser respectively,We obtained the time-resolved images of damage development;On this basis,Complete sync with the lighting of large laser platform with a small laser,t he UV damage detection system was built with a hundred-joule laser platform for damaged light sources;Finally,the interference measurement and the time resolution technique are combined to measure the transient refractive index and free electron density of the plasma during UV damage.The results of this study show that: the 1064 nm pulsed laser focused into the sample resulted in linear damage to the sample in the direction of laser transmission,resulting in a uniform stress wave inside the material;In addition,by increasing the laser pulse at the same position in the body,the growth law of the multiple laser damage morphology is obtained;When the laser is focused on the rear surface of the fused silica,resulting a rapid decline in the shock wave With a large spot,quasi-parallel 351 nm laser pulse target,while observing multiple damage sources,and the shock wave velocity is small.The results of the interference measurement show that the plasma electron density is 1018/ cm3,which decreases from the center to the edge.This paper verifies the feasibility of the nanosecond time-resolved damage testing technique based on the hundred-joule laser platform and the ability of the coherent detection method to detect the physical information of the plasma.