Preliminary mechanical design of the optical blocking filters (OBF), set mounted in X-IFU Aperture Cylinder (AC)

Athena is one of L-class missions selected in the ESA Cosmic Vision 2015-2025 program for the science theme of the Hot and Energetic Universe. The Athena model payload includes the X-ray Integral Field Unit (X-IFU), an advanced actively shielded X-ray microcalorimeter spectrometer for high spectral resolution imaging, utilising cooled Transition Edge Sensors. The X-IFU consists of a large array of TES microcalorimeters that will operate at ~ 50 mK inside a sophisticated cryostat. A set of thin filters, highly transparent to X-rays, will be mounted on the cryostat thermal shields to attenuate the IR radiative load, to attenuate RF electromagnetic interferences, and to protect the detector from contamination. The present document shows the preliminary mechanical design of optical blocking filters (OBF). The filters consist of aluminium coated thin polyimide film supported by a gold plated SS mesh. During the launch, filters are subject to many loads, and the most dangerous for their survival are the mechanical accelerations at the interface with the Dewar and Aperture Cylinder (AC) system of X-IFU instrument.