Exploring gallium alloys for the development of self-healing final mirrors for laser fusion energy power plants

Future inertial fusion energy plants depend on the successful development of the “final turning mirror” which must exhibit high-performance and survivability under multi-giga shot laser irradiation while being directly exposed to the byproducts of the fusion reaction. Here we investigate the potential of a paradigm shifting approach: the use of gallium alloy liquid metal mirrors. These alloys are liquid near room temperature, exhibit reflectance similar to aluminum, and are able to self-heal. A series of characterization and damage testing experiments were conducted, ultimately indicating favorable performance under exposure to 355 nm, 6 ns laser pulses including testing in a vacuum environment. Laser damage in air is associated with the formation of gallium oxide which is mitigated in a vacuum environment. Our results highlight the potential of liquid metal gallium alloys to serve as robust and long-lasting turning mirrors in future power plants.