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Evolution Of Secondary Electron Emission Characteristics Of Spacecraft Surfaces: Importance To Spacecraft Charging, Robert Davies, John R. Dennison
Evolution Of Secondary Electron Emission Characteristics Of Spacecraft Surfaces: Importance To Spacecraft Charging, Robert Davies, John R. Dennison
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A sample of oxidized aluminum was placed inside an ultra-high vacuum (UHV) chamber alongside a piece of PTFE (Teflon®) coated wire and continuously bombarded with 1-3 keV electrons for ~30 hours. The SE yield of the surface was monitored as a function of time throughout the electron bombardment. Oxidized aluminum was chosen as a typical material comprising spacecraft surfaces, while outgassing of the Teflon wire contaminated the UHV environment, simulating the microenvironment surrounding an operating spacecraft. Continuous electron bombardment resulted in two effects—( i) the removal of the oxide layer, and (ii) the deposition of a thin (~1 nm-thick) layer …
Applications Of Secondary Electron Energy- And Angular-Distributions To Spacecraft Charging, Neal Nickles, R. E. Davies, John R. Dennison
Applications Of Secondary Electron Energy- And Angular-Distributions To Spacecraft Charging, Neal Nickles, R. E. Davies, John R. Dennison
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Secondary electron (SE) emission from spacecraft surfaces as a result of energetic electron bombardment is a key process in the electrical charging of spacecraft. It has been suggested that incorporating more complete knowledge of the energy- and angular-distributions of secondary electrons is necessary to fully model how SE emission and spacecraft charging are affected by re-adsorption of low energy electrons in the presence of charge-induced electrostatic fields and ambient magnetic fields in the spacecraft environment. We present data for such energy- and angular-distributions from sputtered, polycrystalline gold surfaces. The data are compared to empirical SE emission models and found to …
Measurements Of Electronic Properties Of Conducting Spacecraft Materials With Application To The Modeling Of Spacecraft Charging, W. Y. Chang, John R. Dennison, Parker Judd
Measurements Of Electronic Properties Of Conducting Spacecraft Materials With Application To The Modeling Of Spacecraft Charging, W. Y. Chang, John R. Dennison, Parker Judd
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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. A complete list of the conducting materials studied, justification of their selection for study, and a summary of the important results of the measurements is presented. This is followed by detailed measurements and analysis for one representative conductor, namely polycrystalline Au. We end with a description of incorporation of these measurements into the NASCAP database.