Large Silicon Carbide Grids for X-Ray Microcalorimeter Blocking Filters

X-ray Microcalorimeter Blocking Filters are a NASA Tier 1 technology gap. Existing soft X-ray filters are fragile and suffer transmittance decay and loss of calibration due to contaminant gettering. We propose to increase the strength of SiC grids to a level suitable for the large apertures of LEM and newAthena. The grids increase the filter temperature to preclude gettering. The grids will also increase the filter acoustic strength for newAthena air launch. The proposed strength increases will reduce the mass density and increase the strength of smaller grids for HEX-P, AXIS, and ARCUS, while reducing artifacts compared with other grid materials. The funding will be used to execute a design-of-experiments testing 9 different strength factors, increasing small grid strength by 2-3X. We will also fabricate a prototype 120mm LEM Main Shell Filter grid, test GEVS Qualification Level vibration performance, and measure vibration stress and damping in vacuum. These will establish a relationship between grid proofing and launch requirements, such that proofing ensures both flight durability and conformance to process capability. The target markets are X-ray telescopes, charged particle detectors, terrestrial X-ray and EUV equipment, UV detectors, and silicon carbide MEMS. The proposed strength increases will reduce the mass density of SiC grids to an even lower level than now possible, increasing their performance advantage relative to copper, nickel, silicon and steel X-ray grids. We expect that at the end of Phase II our fabrication costs will be reduced by 40%, allowing profitable manufacture of grids for terrestrial applications. Some experiments, such as the etching of a newly available silicon carbide 3C-SiC polyphase, may result in even more dramatic cost reduction or strength increases.