Study for dual-function EUV multilayer mirror

Studying the distribution of He+ in Earth's plasmasphere by detecting its resonantly scattered emission at 304 Å will record the structure and dynamics of the cold plasma in Earth's plasmasphere on a global scale. EUV imaging systems usually utilizes near-normal incidence optics including multilayer mirror and filter. In this paper, the space condition of the Earth's plasmasphere to confirm the expected performance of mirror were analyzed. In order to achieve higher response at 304 Å and reduce 584 Å radiation for the optical system, a new multilayer coating of Mo/Si with UO2 was developed. Based on optical constants of Mo, Si and UO2, we used a simplest method to compute the reflectance of this new multilayer mirror range from 100 to 584 Å. The results show the desirable thickness of UO2 is 17 Å, and the multilayer mirror has a high reflectance of 26.10% at 304 Å and a low reflectance of 0.52% at 584 Å.