The objective of this paper is to conduct a systematic examination of the potential cause for spacecraft (S/C) contamination from arcjet thrusters. The problem is scoped to encompass on-orbit activities, and only those effects peculiar to the activation of the arc are considered; other problems common to chemical propulsion are not discussed. Contamination from arcjet thrusters is evaluated following a methodology that has been proven successful in chemical propulsion: contaminant sources are first identified by reviewing and analyzing in depth the thruster design and operation. Once the contaminant species have been identified, their transport paths are examined to derive the incident molecular and particle fluxes arriving to the surfaces of concern, as well as their interaction with said surfaces. The Avco 30-Kw class ammonia arcjet is selected as a working example, given that this thruster has been extensively tested. It was found that thorium may be a source of contamination as it vaporizes from the thoriated tungsten electrodes. Thorium deposition on sensitive surfaces causes blackening and may eventually degrade sensor performance. Other less important sources are tungsten carbide and metallic particles that melting from the electrodes are expelled into the plume. S/C charging and electromagnetic interference (EMI) of spacecraft communications by the arcjet plume are other indirect effects that will require special evaluation studies.
Spacecraft contamination potentials from arcjet thrusters
Moegliche Kontamination von Raumfahrzeugen durch elektrothermischen Antrieb
AIAA-Papers ; May ; 1-10
1987
10 Seiten, 11 Bilder, 4 Tabellen, 9 Quellen
Conference paper
English
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