Investigation of radiation stability of UV optical materials for thermonuclear power plant with KrF laser driver at a linear 10-MeV electron accelerator. Part II. Electron-beam induced absorption in samples

Long-lived electron-beam-induced absorption in a number of UV-optical materials for windows and multilayer coatings of inertial fusion energy reactor and promising KrF laser driver was studied using a pulsed linear electron accelerator with electron energy of 10 MeV. In testing high-purity samples of quartz glasses Corning 7980, KU-1, and KS-4V, as well as crystals of calcium fluoride, magnesium fluoride, and leucosapphire the radiation dose of 18.2 MGy, was comparable to the dose absorbed by windows of KrF electron-beam-pumped laser driver operating for 1 year with a pulse repetition rate of 5 Hz. Quartz glass KS-4V with an admixture of OH showed the lowest absorption with a coefficient of 0.4 cm^-1 at a wavelength of 248 nm among all other glasses. Rather high absorption with a coefficient of 4 cm^-1 in calcium fluoride is effectively bleached by the own KrF laser radiation.