SBIR-STTR Award

Single crystal silicon carbide has properties useful to a wide variety of NASA applications, such as X-ray and EUV filters, charge particle filtering, transducers, and ion propulsion. Compared with other commonly used materials, SiC has higher strength, lower weight, higher X-ray transparency, higher stiffness, higher thermal conductivity, lower ion erosion, and higher temperature capability. PhotonFoils will produce prototype single crystal silicon carbide grids of a size and geometry suitable for planned X-ray microcalorimeters, namely X-IFU and LXM. Smaller grids will also be prepared for statistical pressure strength characterization, and for vibration testing to the NASA GEVS acceptance and qualification levels. Phase I will prepare an 88mm grid per the X-IFU TF4 88mm design rules, while Phase II will prepare 100mm and 126mm grids suitable for the X-IFU TF5 filter and the LXM DMS filter, respectively. Phase II will prepare 2-Level LXM grids analogous to the 2-Level silicon grids used for SXS. Phase II will perform GEVS vibration testing on large filters in vacuum, with geometries and sizes relevant to X-IFU and LXM launch requirements. The proposed grids improve the durability, transmittance, and thermal uniformity of microcalorimeter filters and cooled detector blocking filters. They address identified technical deficiencies and risk items for X-IFU and LXM, namely excess power consumption and fragility. The process used to make the grids can also be tailored to creating large area single crystal SiC membranes, with terrestrial applications such as low-scatter X-ray windows, instrumented X-ray windows, high temperature transducers, and high beam power components. Potential NASA Applications (Limit 1500 characters, approximately 150 words): X-ray microcalorimeter filters, cooled detector blocking filters, grids for EUV telescopes, small telescope entrance filters, charged particle mass/energy filters, neutral atom detectors, ion propulsion, X-ray filter wheel components, stronger substrates for coded apertures, transducers Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): Safe laboratory X-ray source windows, support grids for X-ray filters, energy dissipation grids for e-beam characterization tools, X-ray transparent substrates for high power optical elements (e.g. Fresnel and Laue lenses), thermal dissipation supports for EUV lasers, low-scatter X-ray windows, instrumented diode X-ray windows, high-power x-ray beam splitters Duration: 6

SiC grids address identified risks for the Lynx X-ray Microcalorimeter (LXM) and the Athena X-IFU, such as fragility and excessive power usage. Single crystal SiC grids are a natural extension of single crystal Si for integration into NASA filter grids. SiC has the highest thermal conductivity of all materials besides diamond. Phase I measurements showed SiC grids to be 5X stronger than commercial Si grids. We will fabricate prototype SiC X-IFU and LXM microcalorimeter grids with improved temperature uniformity and strength, addressing identified risks for these instruments. We will also improve EMI shielding and develop a method to create custom outer diameters. Each grid will be strength-proofed to ensure design conformance. Full-sized filters incorporating these grids will be durability tested to advance the TRL of SiC grids for NASA missions. All the Phase I objectives were met, with the following results: -An 88mm X-IFU TF4 grid fabricated from a 150mm SiC wafer -Measurements showing high SiC grid strength -Vibration of two 35mm grids to NASA GEVS, one with an attached 80nm membrane -Demonstration of 3:1 grid bar aspect ratio in small grids -A breakout tab method for producing custom outer frame diameters -A test of grid metallization for improved EMI shielding Phase II objectives are to: -Deliver X-IFU TF5 100mm SiC grids with improved temperature uniformity -Deliver 2-Level LXM DMS 128mm SiC grids with improved durability -Vibration test X-IFU 100mm and LXM 2-Level 128mm grids with attached membranes - Develop a durable aluminum coating to increase EMI shielding -Increasing grid bar aspect ratio and reducing minimum grid bar width for 128mm apertures Achieving these objectives will yield a functional spacecraft grid technology providing unparalleled transmittance, strength and temperature uniformity, while meeting EMI requirements. The objectives advance grid TRL to a level sufficient for consideration by many NASA missions. Potential NASA Applications (Limit 1500 characters, approximately 150 words): X-ray Microcalorimeter Filters, Optical Blocking Filters, Contamination Blocking Filters, EUV Foil Supports, Solar Telescope Entrance Shields, Charged Particle Detector Grids, Ion Drive Grids, High Temperature Transducers, Far Infrared Bandpass Filters, Long-wave Blocking Filters, Quantum Efficiency Enhancement Grids, X-ray Filter Wheel Components, Neutral Atom Detector Grids Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): Gridded X-ray pressure windows, charged particle beam grids, EMI shielding grids, high bandwidth instrumented X-ray windows, X-ray and EUV foil supports, infrared shielding grids for semiconductor EUV equipment, beryllium-alternative X-ray windows, MEMS components, high strength ceramic components, X-ray laser and synchrotron optical components, high energy plasma containment, ion gun grids Duration: 24