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Optical Property Enhancement and Durability Evaluation of Heat Receiver Aperture Shield MaterialsUnder the Solar Dynamic Flight Demonstration (SDFD) program, NASA Lewis Research Center worked with AlliedSignal Aerospace, the heat receiver contractor, on the development, characterization and durability testing of refractory metals to obtain appropriate optical and thermal properties for the SDFD heat receiver aperture shield. Molybdenum and tungsten foils were grit-blasted using silicon carbide or alumina grit under various grit-blasting conditions for optical property enhancement. Black rhenium coated tungsten foil was also evaluated. Tungsten, black rhenium-coated tungsten, and grit-blasted tungsten screens of various mesh sizes were placed over the pristine and grit-blasted foils for optical property characterization. Grit-blasting was found to be effective in decreasing the specular reflectance and the absorptance/emittance ratio of the refractory foils. The placement of a screen further enhanced these optical properties, with a grit-blasted screen over a grit-blasted foil producing the best results. Based on the optical property enhancement results, samples were tested for atomic oxygen and vacuum heat treatment durability. Grit-blasted (Al2O3 grit) 2 mil tungsten foil was chosen for the exterior layer of the SDFD heat receiver aperture shield. A 0.007 in. wire diameter, 20 x 20 mesh tungsten screen was chosen to cover the tungsten foil. Based on these test results, a heat receiver aperture shield test unit has been built with the screen covered grit-blast tungsten foil exterior layers. The aperture shield was tested and verified the thermal and structural durability of the outer foil layers during an off-pointing period.
Document ID
19980013902
Document Type
Reprint (Version printed in journal)
Authors
deGroh, Kim K. (NASA Lewis Research Center Cleveland, OH United States)
Jaworske, Donald A. (NASA Lewis Research Center Cleveland, OH United States)
Smith, Daniela C. (Cleveland State Univ. Cleveland, OH United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1998
Subject Category
Spacecraft Propulsion and Power
Report/Patent Number
NASA/TM-1998-206623
NAS 1.15:206623
AIAA Paper-98-0270
E-11061
Meeting Information
Aerospace Sciences Meeting and Exhibit(Reno, NV)
Funding Number(s)
PROJECT: RTOP 632-1A-1E
Distribution Limits
Public
Copyright
Public Use Permitted.

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NameType 19980013902.pdf STI