Graphene foils improve angular and energy resolution in neutral atom detectors while also improving mass discrimination and usable energy ranges. We developed improved grid supports and achieved areas >10 cm2 with good foil coverage and significant improvements in secondary electron yield from ~1 nm metal oxide overcoats. We present Luxel’s characterization of large-area graphene foils for applications as transmission filters and detector components.
The Lynx x-ray mission will push thin film filters to larger apertures and thinner profiles than those of any preceding mission. We present a study of the uniformity of deposition with existing technology and the consequences of oxidation on 10-15 nm thick Al films on LUXFilm® polyimide. From visible and infrared transmission measurements of thin aluminum filters and the results of a photon-driven oxidation study at the Beamline 1 of the Synchrotron Ultraviolet Radiation Facility at the National Institute of Standards and Technology, we conclude that, from a deposition and oxidation standpoint, Al optical blocking layers at this thickness are viable.
The calorimeter array of the JAXA Astro-H (renamed Hitomi) soft x-ray spectrometer (SXS) was designed to provide unprecedented spectral resolution of spatially extended cosmic x-ray sources and of all cosmic x-ray sources in the Fe-K band around 6 keV. The properties that made the SXS array a powerful x-ray spectrometer also made it sensitive to photons from the entire electromagnetic band as well as particles. If characterized as a bolometer, it would have had a noise equivalent power of <4 × 10 ? 18 W / (Hz)0.5. Thus, it was imperative to shield the detector from thermal radiation from the instrument and optical and UV photons from the sky. In addition, it was necessary to shield the coldest stages of the instrument from the thermal radiation emanating from the warmer stages. These needs were addressed by a series of five thin-film radiation-blocking filters, anchored to the nested temperature stages, that blocked long-wavelength radiation while minimizing x-ray attenuation. The aperture assembly was a system of barriers, baffles, filter carriers, and filter mounts that supported the filters and inhibited their potential contamination. The three outer filters also had been equipped with thermometers and heaters for decontamination. We present the requirements, design, implementation, and performance of the SXS aperture assembly and blocking filters.
The calorimeter array of the JAXA Astro-H (renamed Hitomi) Soft X-ray Spectrometer (SXS) was designed to provide unprecedented spectral resolution of spatially extended cosmic x-ray sources and of all cosmic x-ray sources in the Fe-K band around 6 keV, enabling essential plasma diagnostics. The properties that make the SXS array a powerful x-ray spectrometer also make it sensitive to photons from the entire electromagnetic band, and particles as well. If characterized as a bolometer, it would have a noise equivalent power (NEP) of < 4x10-18 W/(Hz)0.5. Thus it was imperative to shield the detector from thermal radiation from the instrument and optical and UV photons from the sky. Additionally, it was necessary to shield the coldest stages of the instrument from the thermal radiation emanating from the warmer stages. Both of these needs are addressed by a series of five thin-film radiation-blocking filters, anchored to the nested temperature stages, that block long-wavelength radiation while minimizing x-ray attenuation. The aperture assembly is a system of barriers, baffles, filter carriers, and filter mounts that supports the filters and inhibits their potential contamination. The three outer filters also have been equipped with thermometers and heaters for decontamination. We present the requirements, design, implementation, and performance of the SXS aperture assembly and blocking filters.
As-fabricated free-standing indium foils were found to have transmission in the 90nm to 120nm
band ranging from 10% to 70% of modeled values based on pure indium. Auger depth profiling of
the as-deposited indium showed little surface contamination and high purity. However, final freestanding
filters were found to have heavy contamination, particularly on the surface. An
argon/hydrogen plasma bombardment was developed which improved EUV transmission by 50% to
500% in the finished filters without causing significant pinholes to develop in the foils or
appreciably affecting blocking characteristics.
NASA will fly x-ray microcalorimeters on several mission payloads scheduled within the next 5 years. New and
improved blocking filters are urgently needed to realize the full potential and throughput of these missions. High
transmission polyimide support mesh is being developed as an alternative to the nickel mesh currently used in blocking
filter designs. Polyimide's composition affords high transparency to x-rays, especially above 3 keV. A new filter
fabrication technique that simplifies assembly, eliminates adhesives from the filter field, and creates a stronger foil/mesh
bond than epoxy, has also been demonstrated. In addition to support mesh, embedded resistive traces are being
developed to provide deicing capability to actively restore filter performance in orbit. This report details the progress of
this research to date.
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