Thermal Modeling of the ATHENA X-IFU Filters

The X-IFU instrument of the ATHENA mission requires a set of thermal filters to reduce the photon shot noise onto its cryogenic detector and protect it from molecular contamination. The baseline filter consists of a polyimide membrane of 45 nm coated with 30 nm of high pure metallic aluminum mechanically supported by a metallic mesh (stainless steel or niobium) with honeycomb design. Here, we describe the thermal modeling implemented using COMSOL and report the results obtained in different scenarios, namely: the effect of warming up of the outer filter, change of the filter surfaces emissivity, lack of one filter.