Description: 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.

Benefits: In the near term, the proposed grids can serve as backups for planned missions which have no demonstrated solution for blocking filter contamination, particularly microcalorimeter missions. Four of the 45 NASA technology gaps call for improved X-ray blocking filters, and Microcalorimeter Blocking Filters are a NASA Tier 1 Technology Gap. The proposed grid technology can be implemented into semiconductor focal plane detectors to eliminate the severe soft X-ray signal loss encountered by Chandra ACIS (e.g. ARCUS, AXIS, HEX-P and others). The planned grid improvements support the 2021 Astrophysics Decadal survey for new X-ray technology which could enable a Lynx-type X-ray telescope. SiC grid technology can be extended to much higher levels of performance as process technology is further developed. The development and commercialization of our SiC microfabrication technology will advance the TRL of SiC grids in preparation for such a mission. While our proposal focuses on the most technically challenging microcalorimeter filters, the proposed grids can be employed throughout microcalorimeter stacks with beneficial impact on signal and noise. In addition to soft X-ray telescopes, the technology can provide electrostatic grids with superior durability and flatness, while increasing their open area. This will allow instruments with higher energy resolution and imaging capability for spectrometers and microchannel plates. Superior grids can also improve the performance of neutral atom and plasma detectors.The proposed SiC grids can replace silicon, copper, nickel and stainless steel grids for most X-ray and EUV applications. Advantages include high temperature/power operation, high heat dissipation, excellent dimensional stability, superior strength, high open area fraction, and reduced window mass density. The grids eliminate granular scattering and transition metal fluorescence from transmitted X-ray and electron beams. Membranes produced by selective etching will allow low-distortion X-ray transparent sensor arrays, used for synchrotron beam shaping and steering. Ultraflat single crystal windows will allow phase-dependent X-ray imaging, such as biological ptychography, to occur outside of vacuum systems. 3C-SiC substrates may allow economical production of grid bars as narrow as 10microns, stronger and flatter than grids from other materials. The recent introduction of cubic 3C-SiC semiconductor wafers provides leverage into the MEMS market, via increased etch rate and low damage etch capability. 3C-SiC provides electronic properties superior to silicon, and MEMS can operate without hermetic sealing with increased mechanical bandwidth. Our micromachining technology will be an enabler for fabricating SiC MEMS devices in small foundries, and has advantages for fabricating devices requiring low damage, such as quantum computing memory elements. The electronics market includes instrumented membranes for position monitors and fast UV detectors. Example products include: X-ray sample supports with 3X reduced beam occlusion Large X-ray pressure windows with 6X lower mass density X-ray windows for phase-sensitive biological microscopy High-bandwidth low absorption X-ray beam monitors Fast Uutraviolet membrane imagers MEMS for operation in air and harsh environments Beryllium-replacement X-ray windows