Thermomechanical design of the grazing incidence metal mirror of the prometheus-L IFE reactor

In Laser IFE reactors the reflectivity and absorptivity of the grazing metal mirror depend on the neutron dose received by the mirror surface. In addition to these irradiation effects, the surface deformation due to neutron irradiation-induced swelling and due to thermal loads change the focusing quality of the mirror. In the present work, a thorough review of the irradiation effects on the changes in mirror surface quality is presented. A mirror design methodology, which considers the deformation due to the loads associated with laser beam and the deformation due to neutron-irradiation induced swelling is discussed. The basic philosophy considered in the design is to separate the functions and choose the best possible materials to perform these specific functions. An aluminum thin layer, for the purpose of reflection of the laser beam, is deposited on a SiC substrate. The SiC substrate provides a rigid bulk, through which coolant is provided to remove the heat absorbed during laser pulses, and avoids the need for a thicker aluminum layer that undergoes more swelling than SiC. A concrete frame is designed to provide the ultimate resistance against thermally-induced deformation. Other features of the design will also be presented