Measurements of Electronic Properties of Conducting Spacecraft Materials with Application to the Modeling of Spacecraft Charging

摘要

Many spacecraft system anomalies and component failures are known to result from spacecraft charging which is due to the bombardments of spacecraft by energetic electrons, ions, and photons in natural space surrounding [Hastings and Garrett, 1996; Bedingfield et al., 1996; Leach et al., 1995]. To assist spacecraft designers in accommodating and mitigating the harmful charging effects on spacecraft, NASA has developed an extensive set of engineering tools to predict the extent of charging in various spacecraft environments (for example, NASCAP/LEO, NASCAP/GEO, and POLAR) [Mandell et al., 1993]. However, current NASCAP databases lack electronic properties of most spacecraft materials in use (only nine basic materials are presently incorporated) and many new spacecraft bulk materials and coatings need to be characterized. In an effort to improve the reliability and versatility of these models, the NASA Space Environments and Effects (NASA/SEE) Program has funded a study to measure the electronic properties of spacecraft materials related to NASCAP parameters [Dennison, 1998]. The objectives of the study are (i) to provide more accurate measurements together with sufficient materials characterization and (ii) to significantly extend the database to include a wider range of materials that are more representative of the myriad materials used in spacecraft design and incorporates newly developed materials.This paper describes the results of the first stage of this project, measurements of the electronic properties of conducting spacecraft materials. We begin with a description of the required measurements and specifics of the experimental methods used. Representative measurements for gold are described in detail. This is followed by a complete list of the conducting materials studied, justification of their selection for study, and a summary of the important results of the measurements. We end with a description of incorporation of these measurements into the NASCAP database.