| Importance of Surface Conditions for Spacecraft Charging |
Aug 2010 |
6 pages |
| Authors:
Shu T Lai; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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 | This paper studies the importance of secondary and backscattered electrons in spacecraft charging. The secondary and backscattered electron yields from surface materials are affected not only by the energies of the incoming electrons but also by the surface condition. Some typical parameters characterizing the surface condition are the surface smoothness, thickness, surface composition, and surface contamination. By using the published formulae of secondary and backscattered electron yields, the critical temperature ... |
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| The Importance of Surface Conditions for Spacecraft Charging |
08 Jan 2009 |
13 pages |
| Authors:
Shu T Lai; AIR FORCE RESEARCH LAB HANSCOM AFB MA
|
| Spacecraft charging is determined by the ambient plasma environment and the surface properties. Whereas the ambient plasma environment is measured in-situ and in real time, the surface property data rely on measurements conducted previously in the laboratory and empirical formulae derived from the laboratory measurements. This note addresses the importance of surface conditions in determining the spacecraft surface potentials. For example, the surface smoothness, thickness, surface composition, and surface contamination ... |
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| Dependence of Electron Flux on Electron Temperature in Spacecraft Charging |
Jan 2009 |
6 pages |
| Authors:
Shu T Lai; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
|
| Two important observations when the onset of spacecraft surface charging occurs are (1) the electron flux measured in the high-energy (above several keV) channels onboard rises and (2) the ambient electron temperature rises above a critical value. We show by means of an analytical model that the two behaviors are consistent with each other. |
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| On the Anticritical Temperature for Spacecraft Charging |
15 Nov 2008 |
16 pages |
| Authors:
Shu T Lai; Maurice Tautz; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| In recent years, evidence has been found for the existence of a critical temperature for the onset of spacecraft charging to high voltages. High-voltage charging affects scientific instruments on board and is related to spacecraft anomalies. However, less attention has been given to low-voltage charging which can also affect scientific experiments on board and is relevant to surface chemistry. There also can exist an anticritical temperature for low-voltage spacecraft surface ... |
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| Critical Temperature for the Onset of Spacecraft Charging -- The Full Story |
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11 pages |
| Authors:
Shu T Lai; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| The onset of spacecraft charging at geosynchronous altitudes occurs at a critical value of the space plasma electron temperature for a given spacecraft surface. Observations on LANL satellites show that the onset of charging occurs at a critical temperature in almost every charging event, no matter which satellite, which year and which month. The critical temperature values remain the same no matter in eclipse or sunlight. The satellite observations have ... |
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