NASA Scientific and Technical Aerospace Reports

pump. Recall that the prior reported results obtained for the Vertical chamber were nominal at best, showing only a slight
reduction in the arc rate after five heating cycles at the lower bias potentials and virtually no changes at high potential biases.
It was concluded that the vertical chamber was unable to remove enough water vapor from the chamber to adequately test the
arcing criterion. Because the cryo-pumped Teney chamber has a ten times better pumping speed, (40,000 liters per sec
compared to 4,000 liters per sec for the diffusion pumped vertical chamber), a decision was made to retest that experiment
in both the Teney and Vertical vacuum chambers. A comparison of the various data is presented with encouraging results.
Author
Solar Heating; Spacecraft Components; Ground Tests; Vacuum Chambers; Solar Cells
20040111104 Swedish Inst. of Space Physics, Uppsala, Sweden
Wake Effects on Positively Charged Spacecraft in Flowing Tenuous Plasmas: Cluster Observations and Modeling
Engwall, Erik; Eriksson, Anders; Pedersen, Arne; Forest, Julien; Paschmann, Goetz; Quinn, Jack; Torbert, Roy; Torkar, Klaus;
8th Spacecraft Charging Technology Conference; March 2004; 17 pp.; In English; See also 20040111031; No Copyright;
Avail: CASI; A03, Hardcopy
Comparison between electric field measurements made by the double-probe and electron drift instruments on the Cluster
satellites have revealed significant perturbations in the signals from the electrostatic probes when Cluster is on magnetic field
lines above the Earth’s polar cap. In this region, there is a tenuous upflowing plasma known as the polar wind. The polar wind
flow is supersonic, so a wake may form behind spacecraft structures. Usually, one expects wakes to be a problem mostly in
denser plasmas. However, in this very tenuous environment, the spacecraft potential exceeds the kinetic energy of the ions
(flow and thermal), so that the effective size of the wake is determined not by the spacecraft structures themselves, but by the
potential distribution around them. As the plasma is tenuous, this is essentially the vacuum potential, which can extend very
far from spacecraft structures. In particular, wire booms increase their effective size from the order of millimetres to the order
of meters when the electrostatic effect is taken into account. We show the data to be qualitatively consistent with this
interpretation. In particular, an observed alleviation of the effect when artificial potential control is applied lends strong
support. Preliminary results of quantitative modeling and simulations provide additional insight.
Author
Electrical Measurement; Plasmas (Physics); Wakes; Spacecraft Charging
20040111111 Kyushu Inst. of Tech., Kitakyushu, Japan
Issues Concerning the International Standard of ESD Ground Test for GEO Satellite Solar Array
Cho, Mengu; Shikata, Yoshio; Hosoda, Satoshi; Toyoda, Kazuhiro; Amorim, Emanuel; Goka, Tateo; Levy, Leon; Reulet,
Rene; Payan, Denis; 8th Spacecraft Charging Technology Conference; March 2004; 19 pp.; In English; See also
20040111031; No Copyright; Avail: CASI; A03, Hardcopy
As the power level of Geostationary satellites increases, there is more demand of careful ground test on solar array
insulation strength. International atmosphere surrounding commercial telecommunication satellites calls for common
international standard on test conditions. The issues regarding test environment, test circuit, test duration and external
capacitance are reviewed. Results of experiment on the influence of external capacitance on secondary arc formation are
presented.
Author
Geosynchronous Orbits; Electrostatic Charge; Ground Tests; Solar Arrays; Arc Discharges
20040111112 Moscow State Univ., Russia
Features of Charging of Composite Configuration Spacecraft Charging in High Orbits
Mileev, Valery; Makletsov, A. A.; Novikov, L. S.; 8th Spacecraft Charging Technology Conference; March 2004; 12 pp.; In
English; See also 20040111031; No Copyright; Avail: CASI; A03, Hardcopy
Typical feature of spacecraft charging in geosynchronous and high-elliptical orbits in hot magnetosphere plasma is
formation of electrostatic potential distribution on the spacecraft surface (differential charging) and complexity of the charging
dynamics. For mathematical simulation of spacecraft charging in high orbits, the modified version of the COULOMB program
tool was developed in D.V.Skobeltsyn Institute of Nuclear Physics of Moscow State University. The program tool enables to
study dynamics of the spacecraft charging processes in high orbits in various conditions of the spacecraft environment for the
spacecraft models with large number of discretization elements. In the report, the results of modeling of the composite
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