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Measurements of momentum transfer coefficients for H2, N2, CO and CO2 incident upon spacecraft surfacesMeasurements of momentum transfer coefficients were made for gas-surface interactions between the Space Shuttle reaction control jet plume gases and the solar panel array materials to be used on the International Space Station. Actual conditions were simulated using a supersonic nozzle source to produce beams of the gases with approximately the same average velocities as the gases have in the Shuttle plumes. Samples of the actual solar panel materials were mounted on a torsion balance that was used to measure the force exerted on the surfaces by the molecular beams. Measurements were made with H2, N2, CO, and CO2 incident upon the solar array material, Kapton, SiO2-coated Kapton, and Z93-coated Al. The measurements showed that molecules scatter from the surfaces more specularly as the angle of incidence increases and that scattering behavior has a strong dependence upon both the incident gas and velocity. These results show that for some technical surfaces the simple assumption of diffuse scattering with complete thermal accommodation is entirely inadequate. It is clear that additional measurements are required to produce models that more accurately describe the gas-surface interactions encountered in rarefied flow regimes.
Document ID
19980209858
Acquisition Source
Headquarters
Document Type
Other
Authors
Cook, S. R.
(Los Alamos National Lab. NM United States)
Hoffbauer, M. A.
(Los Alamos National Lab. NM United States)
Date Acquired
August 18, 2013
Publication Date
July 16, 1997
Subject Category
Spacecraft Design, Testing And Performance
Report/Patent Number
DE98-000885
LA-UR-97-2898
Funding Number(s)
CONTRACT_GRANT: W-7405-ENG-36
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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