Optimization of cleaning technique for mitigating particulate contamination upon final optics assemblies

Abstract

The cleanliness of the final optics assemblies (FOAs) has become the lynchpin of Inertial Confinement Fusion (ICF). The two-phase flow method is applied to study the motion trajectory of moving aerosol particles in the FOAs. One of efficient clean technology, named purging system with the coupling of low-speed laminar wind and high-speed gas knife to remove particulate pollutants and achieve cleanness of atmospheric environment are designed and analyzed by means of experiments and simulations. Our studies demonstrate that when the exit wind speed of gas knife is more than 40 m/s, the surface temperature unevenness of optical components will certainly exceed 0.2 °C badly reducing the conversion efficiency of FOAs. Investigation of the distance between the outlet of gas knife and the edge of optical lens indicates that the obvious deformation will almost disappear in the region near the outlet of the gas knife when the longitudinal distance is not less than 18 mm. The relationship between the attenuation distance of aerosol particles and the efficiency of purging system is studied in detail. The minimum distance between optical components is elaborately determined to be 170 mm, which realizes the full protection and thorough removal of particulate pollutants on the surface of optical components. Besides, it is thoughtfully settled that backflow at the outlet can be effectively restrained when the height of the backflow chamber is more than 100 mm.