Performance of multilayers in intense synchrotron x‐ray beams

The use of multilayer reflectors under intense synchroton x‐ray beams requires to develop a new generation of multilayered materials that can withstand a high‐power load in excess of 100 W/mm2. Multilayers with the high‐Z layer consisting either of a pure element or of compounds such as carbides, nitrides, or silicides have been produced. Because the fabrication conditions are not yet optimized, thin films with satisfactory layer were not obtained leading to poor reflectivities. Such multilayers have been both thermally annealed in a furnace and exposed to a synchrotron beam with a power density of about 1 W/mm2. The resulting damage ranges from the total destruction of the layering to a reduction of the reflectivity by typically 40%–60%. In some cases an only 1%–15% loss in reflectivity has been observed.