Study On Adhesion And Experiment Of The Particulate Contamination In The Final Optics Assembly Under The Effect Of Intense Laser

High power laser drive is a powerful tool for inertial confinement fusion(ICF) research, and the final optical assembly(FOA) is one of the core assemblies of optical machines of high power laser drive. FOA consists of several pieces of large aperture optical components and machinery parts which is at the end of the whole laser links. It can achieve laser frequency conversion, precise positioning, laser focus and it offers experimental conditions for a variety of extreme states. Contamination of the optical element surface will cause worse passed light intensity and quality, and even damage to the optical element, therefore, the cleanness of FOA is directly related to the success of the target practice experiment. It was found in actual observation that inside of FOA will produce large amounts of aerosols in a short period of time. Many researches aimed on oil, grease and other liquid pollutants, while, the composition, origin and adsorption mechanism of solid particles remain unclear, and it is difficult to explain them experimentally alone, thus research should be conducted on molecular level. Therefore, this paper uses molecular dynamic simulation to analyze the adsorption mechanism of metal particles and the interaction process of laser and the metal particles, and experiment is carried out to study the influencing factors of particle adsorption. This paper has great significance to further enhance optical element surface cleanness.The paper establishes a fused silica molecular model, simulates the adsorption process of aluminum in fused silica surface and describes it in detail from the instantaneous system conformation, aluminum particles centroid height, adsorption force, the overall potential and other aspects of the entire process. This paper uses the theoretical model of the plane absorbing spherical particles to verify the correctness of the simulation model. On this basis, this paper focuses on the influence of surface roughness on the fused silica surface adsorption properties, three representative absorption model are given and fused silica surface "hydrophobic particles" is proposed.Molecular dynamic(MD) is adopted to simulate the interaction process of aluminum particles and the smooth surface of the fused silica and the absorption process of aluminum particles in a defective fused silica surface. It puts emphasis on the interaction process of laser and fused silica surface, and for different sizes of aluminum particles, different analytical methods are used, in terms of instantaneous system conformation, different system temperature, stress distribution and other aspects. The mechanism of laser and metal particles is determined and the source of solid particles in the aerosol is found.The influencing factors on particle absorption force are studied using AFM in the section of experiment. In the research, AFM ball probe is made according to the fabrication process of the modified probe, by measuring the force curves, the absorption force of particles is obtained. The particle material and surface roughness which affect the adsorption force of particles are analysised.