SiC-Based Laser Fusion Optics

65542 Silicon-carbide-based mirrors are essential if inertial fusion energy is to become practical. Current SiC mirror technologies suffer from several shortcomings including high areal density, impurities, low stiffness, and core/base print-through which has precluded producing acceptable SiC mirrors. This project will develop a hybrid SiC-SiC composite/SiC foam approach to address these limitations. The use of the composite core will provide high thermal conductivity, very high modulus/stiffness, high fracture toughness, and a pure ¿-SiC structure. The SiC foam will eliminate the print-through problem. During Phase I, a 4-inch diameter SiC mirror was fabricated that exhibited less than 10 kg/m2 areal density. The core print-through was eliminated, and a very good microroughness of 4 nm was achieved. Phase II will scale-up processing to 18-inch diameter SiC optics suitable for Inertial Fusion Energy optics. Final polishing techniques will be developed to achieve a flatness under 150 nm combined with 2 nm microroughness. An improved aluminum coating method will be developed to achieve an adherent coating layer that will survive pulse laser testing. Commercial Applications and Other Benefits as described by the awardee: Commercial applications should include space optics, such as lidars and cross-link communication, and ground based applications including high energy lasers