Nuclear Assessment of Final Optics of a KrF Laser Driven Fusion Power Plant

In the HAPL program,power plant designs are assessed with targets driven by 40 KrF laser beams. The final optics system that focuses the laser onto the target may include a grazing incidence metallic mirror (GIMM) located at 24 m from the target with 85 ° angle of incidence. The GIMM is in direct line of sight of the target and has a 50 micron thick aluminum coating. Two options were considered for the substrate material; SiC and AlBeMet. The impact of the GIMM design options on the nuclear environment at the dielectric focusing and turning mirrors was assessed. Using AlBeMet results in about a factor of two higher neutron flux. We considered beam duct configuration modifications such as utilizing neutron traps to reduce radiation streaming. In addition, we investigated the impact of lining the beam ducts and neutron traps with different materials that help slowing down and absorbing neutrons.