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Abstract:
Cloud White Tedlar with a multi-layer, thin-film coating on the surface applied by Optical Coatings Laboratory, Inc. (OCLI) is being investigated for potential spacecraft applications. Space environment exposure tests have been performed on a variety of samples exposed to simulated Low Earth Orbit (LEO) and Geosynchronous Orbit (GEO) conditions. The Space Environmental Effects Chamber used to provide the simulation of the LEO and GEO space environment contains a 2500-W xenon arc lamp for long-wavelength ultraviolet (UV) and a 150-W deuterium arc lamp for vacuum UV radiation. Beam sizes are a nominal 10 in. x 12 in. for long-wavelength UV and 7 in. x 7 in. for vacuum UV. The electron beam is about 14 in. x 14 in. with a beam energy variable from 5 keV to 120 keV. All beams are confocal. The large beam area allows multiple samples to be exposed and compared during a test. Several tests have been performed for at least 2500 equivalent sun-hours. The initial value for solar absorptance of the 0.002-in. Cloud White Tedlar film was 0.12, while the multi- layer-coated Cloud White Tedlar was 0.09. After a five-year solar UV exposure, the solar absorptance values were 0.32 and 0.10, respectively. The presence of the coating provides excellent stability to the solar UV compared to uncoated Tedlar. Electron depth dose curves have been calculated for a LEO orbital environment of 410 nmi and for a GEO orbit. These curves are presented along with the selected simulation electron energies and fluences to replicate the expected on-orbit exposure in the coated Tedlar material. Electron irradiations corresponding to LEO and GEO orbits were then performed. All samples were removed for solar absorptance end-of-life measurements. Data are presented for the coated Tedlar material for both LEO and GEO orbital exposures.
| Limitations: |
 APPROVED FOR PUBLIC RELEASE |
| Pages: |
27 |
| Report Date: |
20 AUG 2000 |
| Contract Number: |
F04701-93-C-0094 |
| Report Number: |
A931783 |
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