title: Advanced materials for multilayer mirrors for extreme ultraviolet solar astronomy.
abstract: We provide an analysis of contemporary multilayer optics for extreme ultraviolet (EUV) solar astronomy in the wavelength ranges: λ=12.9-13.3  nm, λ=17-21  nm, λ=28-33  nm, and λ=58.4  nm. We found new material pairs, which will make new spaceborne experiments possible due to the high reflection efficiencies, spectral resolution, and long-term stabilities of the proposed multilayer coatings. In the spectral range λ=13  nm, Mo/Be multilayer mirrors were shown to demonstrate a better ratio of reflection efficiency and spectral resolution compared with the commonly used Mo/Si. In the spectral range λ=17-21  nm, a new multilayer structure Al/Si was proposed, which had higher spectral resolution along with comparable reflection efficiency compared with the commonly used Al/Zr multilayer structures. In the spectral range λ=30  nm, the Si/B4C/Mg/Cr multilayer structure turned out to best obey reflection efficiency and long-term stability. The B4C and Cr layers prevented mutual diffusion of the Si and Mg layers. For the spectral range λ=58  nm, a new multilayer Mo/Mg-based structure was developed; its reflection efficiency and long-term stability have been analyzed. We also investigated intrinsic stresses inherent for most of the multilayer structures and proposed possibilities for stress elimination.
authors.forename: S A
authors.initials: SA
authors.lastname: Bogachev
authors.forename: N I
authors.initials: NI
authors.lastname: Chkhalo
authors.forename: S V
authors.initials: SV
authors.lastname: Kuzin
authors.forename: D E
authors.initials: DE
authors.lastname: Pariev
authors.forename: V N
authors.initials: VN
authors.lastname: Polkovnikov
authors.forename: N N
authors.initials: NN
authors.lastname: Salashchenko
authors.forename: S V
authors.initials: SV
authors.lastname: Shestov
authors.forename: S Y
authors.initials: SY
authors.lastname: Zuev