Long-Term Survival of Grazing-Incidence Metal Mirrors for Laser Fusion

The grazing incidence metal mirror is a promising option for the final optic in a laser-driven inertial fusion energy power plant. It has been pursued as an alternative to multi-layer dielectric mirrors based on expectations of higher radiation damage resistance. Aluminum offers high reflectivity over a broad range of wavelengths extending deep into the ultraviolet part of the spectrum, and thus offers special advantages for an excimer laser driver. In this article, we describe the fundamental phenomena of laser-induced metal mirror damage and lifetime, strategies for mirror fabrication, our experimental facility and techniques, and the results of fabrication and test campaigns over the past several years.