ATHENA optimized coating design

The optimization of coating design for the ATHENA mission si described and the possibility of increasing the telescope effective area in the range between 0.1 and 10 keV is investigated. An independent computation of the on-axis effective area based on the mirror design of ATHENA is performed in order to review the current coating baseline. The performance of several material combinations, considering a simple bi-layer, simple multilayer and linear graded multilayer coatings are tested and simulation of the mirror performance considering both the optimized coating design and the coating baseline including on- and off-axis effective area curves are presented. We find that the use of linear graded multilayers can increas by 37% the integraed effective area of ATHENA in the energy range between 0.1 keV and 15keV.