Study On Key Technologies For Damage Removal Processing Of Fused Silica Surfaces With Atmospheric Pressure Plasma

Fused silica optics have been widely used in high-power laser systems,such as in the Inertial Confinement Fusion system(ICF).It's a problem to process optics of fused silica with less subsurface damage efficiently.Atmospheric Pressure Plasma Processing technology is a new machining method to process optics of silicon-based material.As a chemical processing method,plasma processing will not produce damage.At the same time,plasma processing can also effectively remove surface damage(SD)and subsurface damage(SSD)caused by mechanical processing.Based on these advantages of plasma processing,this paper introduces it into the machining process of large-aperture fused silica optics.Some research is done on plasma processing,the main contents and results are as follows:(1)The principle of Atmospheric Pressure Plasma Processing is studied,including the material removal principle and the producing principle of inductively coupled plasma processing.Besides,as the foundation of experimental study,a new Atmospheric Pressure Plasma Processing system is designed to meet the requirement of the optics to be fabricated.(2)Some research is done on removing damage of fused silica by plasma processing.At first,the ability of plasma processing to remove damage of fused silica is verified.And then,the damage removal course is studied by observing surface micro-scale morphology after different removal depth of plasma processing.Besides,different grinding damage is removed by plasma processing to confirm the position of plasma processing in the machining process of fused silica.Finally,the damage removal model of plasma processing is analyzed according to damage size changing with the removal depth.(3)Some details about the removal function of Atmospheric Pressure Plasma Processing technology is studied in surface shape processing,including the method to get accurate removal function,robustness of the removal function,and the relationship between function and some processing parameter.The results show that the removal function of plasma processing should be gotten through linear sweep method and has a good robustness.Besides,the results also indicate that the removal function have little change with the angle of incidence(within 15o)but obvious change with the sweep speed.This is mainly due to the heating effect.(4)Some research is done on evenly removal in plasma surface shape processing.There are edge effect and heat accumulation effect in plasma surface shape processing.The former can be solved by extending edge and the latter can be solved by optimizing machining path.The evenly removal experiment is taken on large-diameter fused silica optics,including plane mirror and sp herical mirror.Results of the experiment show some problems and the analysis of the problems is done in the article.The research results of this paper show that the processing demand about removing damage with high efficiency is achieved by Atmospheric P ressure Plasma Processing technology and a new machining process of large-diameter fused silica optics should contain plasma processing.So this paper has a high engineering significance on the processing of large-diameter fused silica optics.