Presentation Information
[2I09]Experimental Evaluation of Radiation Damage to Dielectric Mirrors by Helium ion in Laser Fusion Reactors
*Takumi Sato1, Yasuyuki Ogino2, Diancheng Geng2, Akira Hasegawa2, Ryuta Kasada2, Misako Miwa2, Shigeo Matsuyama2, Keisuke Shigemori1, Kohei Yamanoi1 (1. Osaka Univ., 2. Tohoku Univ.)
Keywords:
Laser fusion,Final optics,Dielectric mirror,Helium
To evaluate the radiation resistance of dielectric mirrors used in laser fusion reactors, an experiment was conducted using the Dynamitron accelerator at Tohoku University’s Fast Neutron Laboratory (FNL). Helium ion beams were irradiated onto HfO2/SiO2 multilayer mirrors, and changes in reflectance and mirror damage were assessed. After irradiation with Helium ions at an energy of 1.5 MeV and a fluence of 2.5×1018/cm2, the mirrors completely failed, exhibiting blistering on the surface, delamination of the multilayers, and void formation within the substrate. These changes were primarily due to damage caused by cracks and blisters resulting from the helium forming and growing bubbles in the material.