NASA Scientific and Technical Aerospace Reports

27
NONMETALLIC MATERIALS
Includes physical, chemical, and mechanical properties of plastics, elastomers, lubricants, polymers, textiles, adhesives, and ceramic
materials. For composite materials see 24 Composite Materials.
20040111036 Musashi Inst. of Tech., Tokyo, Japan
Measurement of Bulk Charge in Dielectric Materials Irradiated by Electron Beam in Vacuum Environment
Osawa, N.; Takahashi, S.; Tanaka, Y.; Takada, T.; Watanabe, R.; Tomita, N.; Griseri, V.; Levy, L.; Laurent, C.; 8th Spacecraft
Charging Technology Conference; March 2004; 7 pp.; In English; See also 20040111031; No Copyright; Avail: CASI; A02,
Hardcopy
Bulk charge accumulation in thin dielectric materials under electron beam irradiation in vacuum environment was
observed using newly developed measurement system. Recently, some accidents in spacecraft due to the charging up of
electric potential have been reported. Some of them are caused by surface discharge normally happens in plasma environment.
Some others seem to be caused by discharge due to and an accumulation of charge in bulk of materials at relatively higher
altitude environment. Surface charge is usually measured using surface potential meter. However, there had been no useful
method to measure the bulk charge in the materials. Therefore, we have been developing the bulk charge measurement system.
We have already succeeded in measuring the bulk charge distribution in thick sample under electron beam irradiation in air
atmosphere. However, to simulate the actual spacecraft in condition of high altitude space environment, it is necessary to carry
out the measurement for thin materials in vacuum environment. Therefore, we have developed an improved measurement
system applicable to a thin sample in vacuum environment. Using the improved system, we carried out the measurement of
bulk charge distributions in 180 and 50 m thick Kapton and PET film under electron beam irradiation in vacuum of ca 10-6
Pa. In this report, some typical measurement results are introduced following the explanation of brief measurement principle.
Author
Charge Distribution; Dielectrics; Irradiation; Electron Beams; Vacuum
20040111053 Musashi Univ., Tokyo, Japan
Characteristic of Charge Accumulation in Glass Materials Under Electron Beam Irradiation
Miyake, H.; Tanaka, Y.; Takada, T.; 8th Spacecraft Charging Technology Conference; March 2004; 9 pp.; In English; See also
20040111031; No Copyright; Avail: CASI; A02, Hardcopy
We observed space charge formation in various glass materials under electron beam irradiation. Spacecraft charging
occurs in plasma and radiation environment. Especially we have focused on an accident caused by internal charging in glass
material used cover of solar array panel. Therefore we have tried to measure the charge distribution in glass materials
irradiated e-beam. The measurement is carried out using PEA (Pulsed Electro-Acoustic method) system. Two types of glass
materials are used for samples. One is a quartz glass (pure SiO2), and another are glasses including impurities of oxide metal.
In the case of quartz glass, charge accumulation was not observed neither during nor after electron beam irradiation. On the
other hand, charge accumulation was observed in glass sample including metal-oxide impurities. We found the polarity of the
observed charges in bulk depends on the content of impurities. To confirm the existence of which impurity dominates the
polarity of the accumulated charge, we measured charge distribution in several glass materials including various metal-oxide
impurities.
Author
Charge Distribution; Accumulations; Glass; Electron Beams; Irradiation; Silicon Dioxide
20040111065 Applied Sciences, Inc., Cedarville, OH, USA
Carbon Nanofiber-Filled Materials for Charge Dissipation
Jacobsen, Ronald L.; Walters, Kent R.; Glasgow, D. Gerald; Wang, Chyi-Shan; 8th Spacecraft Charging Technology
Conference; March 2004; 6 pp.; In English; See also 20040111031; No Copyright; Avail: CASI; A02, Hardcopy
This work explores the possibility of using carbon nanofibers to create improved versions of antistatic and conductive
polyimide (e.g. Kapton.) for use in satellite charge control and dissipation. Carbon nanofibers have superior properties making
them a candidate for this application, including very small diameter (to fit within a thin film), high aspect ratio (to form a
network), moderate electrical conductivity, and excellent dimensional stability. Nanofibers in the diameter range from 60 - 200
nm (as distinct from smaller nanotubes) are now available relatively cheaply and in quantity. The primary challenge in making
polyimide films is achieving adequate dispersion of nanofibers. This is complicated both by the fact that the nanofibers are
entangled as produced, and that they are not naturally well wet by the polymer, causing them to agglomerate during processing
prior to polyimide film casting. This paper describes methods for surface modification of nanofibers, as well as size separation
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