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Giaretta, et al. Hsiao, et al. Du kanske gillar. Permanent Record Edward Snowden Inbunden. Hooked Nir Eyal Inbunden. Spara som favorit. Skickas inom vardagar. Specifically, visible, UV and FUV mirrors coated with bare aluminum to achieve unparalleled reflectivity in space. Lee Show Abstract. The next generations of Cosmic Microwave Background CMB polarimetry experiments will attempt to detect the faint primordial B-mode signal from gravitational waves.
The increasing scale of photon-noise limited detector arrays of millimeter-wave astrophysics has led to the need for cryogenic refractive optics with large aperture, high dielectric constant, and low loss. Additionally, multiple frequency band observations for galactic foreground removal from CMB signal require broad bandwidth optics.
The Space Review: Building a bridge to space solar power for terrestrial use
Modern CMB polarimetry experiments use several cryogenically cooled refractive elements made of alumina or silicon. Their high dielectric constants require multiple layers of anti-reflection AR coating with different dielectric constants to minimize reflection at the dielectric boundaries. We have developed an AR coating technology for millimeter-wave optics which achieves minimal dissipative loss and broad bandwidth with a simple and accurate fabrication process. Ceramic coatings are applied using a standard plasma spray system.
We tune the dielectric constant of the coating by mixing hollow ceramic microspheres with alumina powder as the base material or varying the parameters of the plasma system. By spraying low loss ceramic materials with a tunable dielectric constant, we can apply multiple layers of AR coating for broadband millimeter-wave detection.
The ceramic coating also has matching coefficient of thermal contraction with alumina and silicon for robustness to cryogenic delamination. We report on the design, fabrication methodology, and measurement of coating uniformity, repeatability, and transmission at room and cryogenic temperatures.
This technology is applicable from submillimeter to millimeter wavelengths for coatings with greater than octave bandwidth. Characterization techniques and qualification tests of glass and optical coatings for space applications Author s : Maria G.
Pelizzo ; Alain J. Optical coatings and materials need to be qualified against space environmental agents, such as protons, helium ions and electrons. The induced damage effects are studied in dependence on ion species, energy, flux and fluence. Results show that damages can be dramatically dependent not only by fluence, but also by ions energy, so that qualification should take this factor into account.
The significance of results obtained by using gamma-rays in place of ions irradiation to qualify components is briefly discussed. A systematic experimental plan for an extensively study of the irradiation effects induced in a large number of different sample coatings and materials is presented. Using ellipsometry and x-ray photoelectron spectroscopy for real-time monitoring of the oxidation of aluminum mirrors protected by ultrathin MgF2 layers Author s : Brian I.
Johnson; Tahereh G. Avval ; Grant T. Allred ; Matthew R. Linford Show Abstract. To maintain high, broad-band reflectance, thin transparent fluoride layers, such as MgF 2 , are used to protect the of aluminum mirrors against oxidation since aluminum oxide absorbs short wavelength light.
In this study, we present, for the first time, combined X-ray photoelectron spectroscopy XPS and ellipsometric SE studies of aluminum oxidation as a function of MgF 2 over a range of layer thickness nm. For each SE data set, because the optical constants of ultrathin metals films depend strongly on deposition conditions and their thickness, the optical constants for Al, as well as the Al and Al 2 O 3 thicknesses, were fit.
SE trends were confirmed by X-ray photoelectron spectroscopy.
SPACE TECHNOLOGY PROCEEDINGS
The extent of oxide growth can be modeled from the relative area of each peak once they are corrected for the attenuation through MgF 2 layer. Here, k is a factor which depends only on MgF 2 thickness, and decreases with increasing MgF 2 thickness. The techniques developed can illuminate other protected mirror systems. A review of extreme ultraviolet EUV multilayers for solar physics applications is presented. Several promising material couples, as well as different optimization strategies, have been explored to optimize the peak reflectance at different wavelengths.
For example, ad-hoc capping layers can be employed both to protect the structure underneath and to enhance the reflectance performance at a specific wavelength or to achieve other features such as spectral width and purity. Wide-band and multiband EUV coatings can be achieved by using a-periodic designs, which are still largely unexplored. Aperiodic structures provide novel solutions to be considered in view of future space missions.
All the proposed designs are discussed considering their stability in time and along space missions. Mathematical analysis of hexagonal source arrangement for making uniform reflective aluminum coatings Author s : D. Sheikh ; Manuel A. Richardson Show Abstract. This paper presents modeling results for coating thickness as a function of position, for aluminum films made with a hexagonal array of evaporation sources.
The computer simulation is based on measured plume data from a single evaporation source. The model is used to determine optimum source spacing for a given plume shape. The analysis revealed that arrangement of multiple sources in a hexagonal array can produce uniform coatings while utilizing a reasonable number of evaporation sources per square meter of coating area. Monte Carlo simulations followed by gradient descent optimization methods were used to determine optimal flatness solutions for groups of deposition sources with varied deposition times.
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