Study Of Preparation Technology Of Gradient Mental Coating For ICF

Component density gradient coating is a kind of thin film material formed by the linear change of the content of two elements with large difference in density.In inertial confinement fusion（ICF）physics experiments,composition density gradient coating often used as the inner layer of double shell target to alleviate the hydrodynamic instability perturbation during ignition,Therefore,the preparation of low surface roughness component density gradient coating that meets the requirements of ICF experiment is very important.In this work,we focused on the preparation of component density gradient coating and the evolution of the surface roughness.In this thesis,gradient coatings ware prepared by using super-vacuum dc magnetron sputtering equipment,this paper mainly summarizes the following three aspects,and some outstanding results have been obtained in the research of high Z-low Z（Z is the atomic number）component density gradient coating.The main findings are as follows:（1）The influence of different low Z elements on the surface roughness of plane component density gradient coating.The results showed that the surface roughness of the tungsten/aluminum gradient coating was the smallest among the three high-low Z component density gradient coatings on the plane,and the Rq value was 4.2±0.3 nm.Tungsten/carbon gradient coating was followed by an Rq of 5.2±0.4 nm.The tungsten/aluminum gradient coating had the maxim um surface roughness of 5.3±0.6 nm.The tungsten/carbon gradient coating forms wc_1-x during the sputtering process,while theα-phase tungsten andβ-phase tungsten appear in the tungsten/silicon and tungsten/aluminum gradient coatings,respectively.It is obviously that different low Z elements have a great influence on the surface roughness of the component density gradient coating.（2）Influence of different thickness on the surface roughness of the component density gradient coatings.The results showed that in the tungsten/carbon gradient coating,the surface roughness increased first and then decreased with the increase of thickness,and the minim um surface roughness was 1.36 nm when the film thickness was 2.5 um.With the increase of thickness,the surface roughness of tungsten/silicon gradient coating decreases first,then increase,and finally decrease again.When the film thickness is 1 um,the minimum surface roughness of 1.16 nm is obtained.For tungsten/aluminum gradient coating,the surface roughness increased gradually with the increase of thickness,while the minim um was 6.01nm when the thickness of the film was 0.5 um.For each component density gradient coating,the effect of thickness on its surface roughness is inconsistent.（3）Influence of different low Z elements on the surface gradient coatings of PAMS microspheres.For the three kinds of component density gradient coatings on the surface of PAMS microspheres,the surface roughness of the W/C coating is 55.6±9.0 nm,the surface roughness of the W/Si coating is 62.9±7.5 nm,and the surface roughness of the W/Al coating is 67.9±11.4 nm.The factors influencing the surface roughness of the coating include different low Z elements,the grain size of the coating and the phase composition of the film.The component density gradient coating with small surface roughness is a good candidate for the inner layer materials of double shell target,which will promote the investigation of ICF.