NASA Scientific and Technical Aerospace Reports
NASA Scientific and Technical Aerospace Reports
NASA Scientific and Technical Aerospace Reports
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20040111087 Science Applications International Corp., San Diego, CA, USA<br />
NASCAP-2K as a PIC Code<br />
M<strong>and</strong>ell, M. J.; Cooke, D. L.; 8th Spacecraft Charging Technology Conference; March 2004; 13 pp.; In English; See also<br />
20040111031; No Copyright; Avail: CASI; A03, Hardcopy<br />
Nascap-2k can be used to calculate plasmadynamic effects as well as steady-state charging <strong>and</strong> current collection. In this<br />
paper we consider electron dynamics in the sheath of a VLF antenna. We estimate the sheath size, <strong>and</strong> show 1-D calculations<br />
for both sine wave <strong>and</strong> square wave excitation. The results show strong electrostatic plasma oscillations at the sheath edge.<br />
Then we use Nascap-2k to duplicate the square wave results through the first maximum in the plasma oscillation, obtaining<br />
excellent agreement with the 1-D results. This opens the door to fully 3-D dynamic VLF antenna calculations.<br />
Author<br />
Spacecraft Charging; Spacecraft Antennas; Very Low Frequencies; Computerized Simulation<br />
20040111088 Kyushu Inst. of Tech., Kitakyushu, Japan<br />
High Voltage Solar Array for 400V Operation in LEO Plasma Environment<br />
Hosoda, Satoshi; Okumura, Teppei; Cho, Mengu; Toyoda, Kazuhiro; 8th Spacecraft Charging Technology Conference; March<br />
2004; 10 pp.; In English; See also 20040111031; No Copyright; Avail: CASI; A02, Hardcopy<br />
To realize a MW-class space platform, the power must be delivered at least 400 volts. In order to realize 400 volts<br />
operation in LEO, arcing caused by interaction between the spacecraft <strong>and</strong> the surrounding LEO plasma must be overcome.<br />
The purpose of the present paper is to report on the results of laboratory experiment carried out to develop solar array capable<br />
of generating electricity at 400V in LEO plasma environment. We tested various types of solar array designs. We biased solar<br />
array coupon panels negatively inside a vacuum chamber <strong>and</strong> measured the arc inception rate for each design. The arc sites<br />
were also located to identify the weakness of each design. These data are compared to the characteristics of conventional solar<br />
array for 100V bus satellite. We confirmed that covering array strings by transparent film <strong>and</strong> by large coverglass is promising.<br />
The advanced coverglass coupon is most realistic design.<br />
Author<br />
High Voltages; Low Earth Orbits; Solar Arrays; Space Platforms; Electricity; Plasmas (Physics)<br />
20040111089 European Space Agency. European Space Research <strong>and</strong> Technology Center, ESTEC, Noordwijk, Netherl<strong>and</strong>s<br />
Secondary Electron Emission Causing Potential Barriers Around Negatively Charged Spacecraft<br />
Samplon, Eloy Sasot; Hilgers, Alain; Thiebault, Benoit; Genot, Vincent; Eriksson, Anders I.; 8th Spacecraft Charging<br />
Technology Conference; March 2004; 8 pp.; In English; See also 20040111031; No Copyright; Avail: CASI; A02, Hardcopy<br />
Low-energy secondary electrons have been observed to be reflected back to the spacecraft during eclipse conditions. It<br />
has been argued that the presence of negative potential barriers can be caused by the secondary electron emission space charge<br />
<strong>and</strong> may play a role in the spacecraft charging process. The barriers turn back the low-energy spacecraft-emitted electrons <strong>and</strong><br />
prevent the low-energy ambient electrons from reaching the detector. Two numerical methods previously presented by<br />
Whipple <strong>and</strong> by Parrot et al. in the literature have been used to study the effect of secondary electrons on potential barriers<br />
negatively charged spacecrafts. The former method provides an upper bound for the potential barriers when the sheath is large<br />
compared to spacecraft dimension. The latter one provides in principle the exact sheath profile subject to accurate integration<br />
of the density distribution over the energy. The application of the methods to data provided by the ATS6 <strong>and</strong> Freja spacecraft<br />
suggests that the high level negative charging is not due to barriers induced by secondary electron emission space charge.<br />
Author<br />
Secondary Emission; Spacecraft Charging; Spacecraft Design; Mathematical Models; <strong>Aerospace</strong> Vehicles<br />
20040111093 Alcatel Space Industries, Cannes la Bocca, France<br />
Modeling of the Plasma Thruster Impact on Spacecraft Charging<br />
Brosse, S.; Clerc, S.; 8th Spacecraft Charging Technology Conference; March 2004; 14 pp.; In English; See also<br />
20040111031; No Copyright; Avail: CASI; A03, Hardcopy<br />
This paper presents the recent investigations done by the Research Department of Alcatel Space in the modelling of the<br />
electrostatic impact of plasma thruster on spacecraft charging. In particular, we will question the validity of the generally<br />
accepted hypothesis of Maxwell-Boltzmann distribution for the electron especially to take account of the plasma contactor<br />
effect. In a first part, we will present the problem of the Maxwell-Boltzmann distribution to correctly model the spacecraft<br />
charging modification due to plasma thruster in the software SPARCS developed by Alcatel Space. We will show that the<br />
plasma contactor effect of a plasma thruster is essential to estimate <strong>and</strong> model the electrostatic impact of the thruster. We will<br />
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