Research On Cleaning Technology Of Particles And Organic Contaminants On The Surface Of Fused Silica Optical Components

Laser inertial confinement fusion is an important scientific method for mankind to solve the energy crisis and explore the evolution of matter u nder extreme conditions.The cleanliness of each component in the laser inertial confinement fusion device has clear and stringent requirements.How to maintain the surface cleanliness of large-diameter optical components and metal components and the cleanliness of the internal space of the device is an urgent need in high-power laser devices.Precision cleaning of large-diameter optical components and mechanical components is an important way to obtain surfaces with high cleanliness.In-situ and off-situ cleaning methods have been applied and developed in the device.In-situ cleaning methods such as laser cleaning,plasma cleaning,and air knife purging are all used in high-power laser devices.In this paper,the particle splashing process in the process of fused silica laser damage is studied,and the organic pollutants inside the device are sampled and analyzed.The research on laser in-situ cleaning methods is carried out.Finally,the mechanism of off-situ cleaning of organic pollutants for optical components was studied,and the effect of off-situ cleaning methods on the removal of organic pollutants.The following research was carried out:Firstly,the sputtering behavior of particles during nanosecond laser damage was studied,and the relationship between the particle size of sputtered particles and the laser energy density and the number of laser shots was deeply studied.The particles after settling were then characterized,and it was observed that there were a large number of fragments caused by mechanical stress around the damaged pit.The molecular dynamics method was used to simulate and study the mechanism of sputtering produced by fused silica material under the action of the shock wave.Secondly,for the particle pollutants generated in the laser damage process,the laser cleaning research of particle pollutants was carried out.A three-dimensional model of laser cleaning was established,and the influence of laser incident direction,particle size,laser energy density,particle type and laser wavelength was studied by the method of multi-physics coupling.Transparent glass particles focus on the laser beam.The temperature field and thermal expansion of the particles are different under different laser incident directions.When the laser is inci dent on the transparent particles in the forward direction,the temperature at the interface between the particle and the substrate is higher than when the laser is incident in the back direction.The laser cleaning threshold of metal particles is affected by the laser incident direction,while the cleaning efficiency of spherical fused silica particles and soda-lime glass particles is not related to the laser incident direction.In addition,it was found that the degree of particle agglomeration on the fus ed silica surface also affects the laser cleaning efficiency of the particles.Thirdly,the research work on laser cleaning organic pollutant dimethyl silicone oil was carried out.First,the organic pollutants in the atmosphere and on the surface of components were detected,and the adsorption of typical organic molecules on the surface of fused silica was studied from the nanometer scale.Elevated temperature facilitates the desorption of gaseous organic pollutants.The paper establishes a finite element model of laser cleaning oil film,analyzes and compares the temperature field without oil film and with oil film,and determines the appropriate range of laser cleaning process parameters.Finally,the ultrasonic-assisted cleaning and desorption technology of alkane pollutants in surfactant solution was studied.The study found that the length of the hydrophilic end of the surfactant molecule in the surfactant solution is crucial for the desorption of pollutants.The changes in hydrogen bonds and residual time during the desorption of alkane pollutants were revealed.The effect of cleaning temperature on the desorption process of pollutants was discussed.Afterwards,the contaminant residue mechanism in the simulation was indirectly verified by ultrasonic-assisted surfactant cleaning experiments on fused silica.