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Induced charging of shuttle orbiter by high electron-beam currentsEmission of high-current electron beams that was proposed for some Spacelab payloads required substantial return currents to the orbiter skin in order to neutralize the beam charge. Since the outer skin of the vehicle was covered with approximately 1200 sq m of thermal insulation which has the dielectric quality of air and an electrical conductivity that was estimated by NASA at 10 to the -9 power to 10 to the -10 power mhos/m, considerable transient charging and local potential differences were anticipated across the insulation. The theory for induced charging of spacecraft due to operation of electron guns was only developed for spherical metal vehicles and constant emission currents, which were not directly applicable to the orbiter situation. Field-aligned collection of electron return current from the ambient ionosphere at orbiter altitudes provides up to approximately 150 mA on the conducting surfaces and approximately 2.4 A on the dielectric thermal insulation. Local ionization of the neutral atmosphere by energetic electron bombardment or electrical breakdown may provide somewhat more return current.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Liemohn, H. B.
(Battelle Pacific Northwest Labs. Richland, WA, United States)
Date Acquired
August 9, 2013
Publication Date
February 24, 1977
Publication Information
Publication: NASA. Lewis Res. Center Proc. of the Spacecraft Charging Technol. Conf.
Subject Category
Space Transportation
Accession Number
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.
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