[PDF] High Level Spacecraft Charging Environments Near Geosynchronous Orbit eBook

Author : E. G. Mullen
Publisher :
Page : 52 pages
File Size : 42,2 MB
Release : 1982
Category : Electrons
ISBN :

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High-level spacecraft charging events in sunlight are discussed and statistically analyzed to determine environmental parameters critical to charging and the region of space near geosynchronous altitude where charging occurs. Significant levels of spacecraft charging are shown to occur only between 1900 LT and 0900 LT at any altitude or latitude of the SCATHA satellite orbit. High-level charging is shown to occur only during periods when the magnetic activity index is 2+ or greater. Distribution functions of energetic electrons and ions are presented for 3 high-level charging periods on days 114, 241 and 363, 1979. Moments of the distribution functions are determined, and fitting techniques used to derive two-Maxwellian densities and temperatures are discussed. Results are provided in a format usable in satellite design specifications.

Author : E. G. Mullen
Publisher :
Page : 0 pages
File Size : 31,95 MB
Release : 1982
Category : Electrons
ISBN :

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High-level spacecraft charging events in sunlight are discussed and statistically analyzed to determine environmental parameters critical to charging and the region of space near geosynchronous altitude where charging occurs. Significant levels of spacecraft charging are shown to occur only between 1900 LT and 0900 LT at any altitude or latitude of the SCATHA satellite orbit. High-level charging is shown to occur only during periods when the magnetic activity index is 2+ or greater. Distribution functions of energetic electrons and ions are presented for 3 high-level charging periods on days 114, 241 and 363, 1979. Moments of the distribution functions are determined, and fitting techniques used to derive two-Maxwellian densities and temperatures are discussed. Results are provided in a format usable in satellite design specifications.

Author :
Publisher :
Page : 13 pages
File Size : 28,61 MB
Release : 2004
Category :
ISBN :

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We present the results of a statistical study on high-level spacecraft charging at geosynchronous altitudes. Below the critical temperature T* for a surface material, no spacecraft charging occurs. The spacecraft charging potential data are obtained from the ion line of the ion energy spectrum. If the ion line can not be clearly identified, the data point is flagged and not used in our analysis. Since T* depends on the surface material and since each satellite has its own surface material or materials, each satellite is expected to have its own critical temperature. The coordinated space environmental parameter data of the Los Alamos National Laboratory (LANL) include spacecraft charging data measured on several geosynchronous satellites in eclipses and in sunlight over years. We have obtained statistical results of T* for each satellite studied and found that, beyond T*, the high-level spacecraft potential increases almost linearly with the ambient electron temperature. Amazingly, the critical temperature in sunlight remains the same as in eclipse, agreeing with the monopole-dipole differential charging model. This work offers a useful method not only for predicting the onset of spacecraft charging in eclipse and in sunlight but also for predicting high-level spacecraft charging potential with reasonable accuracy at any given ambient electron temperature in the geosynchronous environment.

Author : Henry B. Garrett
Publisher : John Wiley & Sons
Page : 202 pages
File Size : 31,42 MB
Release : 2012-05-22
Category : Science
ISBN : 1118186451

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The definitive guide to the modern body of spacecraft charging knowledge—from first principles for the beginner to intermediate and advanced concepts The only book to blend the theoretical and practical aspects of spacecraft charging, Guide to Mitigating Spacecraft Charging Effects defines the environment that not only creates the aurora, but which also can have significant effects on spacecraft, such as disruption of science measurements and solar arrays from electrostatic discharge (ESD). It describes in detail the physics of the interaction phenomenon as well as how to construct spacecraft to enhance their survivability in the harsh environment of space. Combining the authors' extensive experience in spacecraft charging—and in their provision of design support to NASA, JPL, the commercial satellite market, and numerous other projects—this incredible book offers both a robust physics background and practical advice for neophytes in the field and experienced plasma physicists and spacecraft engineers. In addition to containing numerous equations, graphs, tables, references, and illustrations, Guide to Mitigating Spacecraft Charging Effects covers: Solar cell technology, especially higher voltage arrays, and the new design approaches that are appropriate for them Information about the space plasma environment New analytic computer codes to analyze spacecraft charging Spacecraft anomalies and failures which emphasized designs that are of greater importance than others

Author : E. G. Mullen
Publisher :
Page : 42 pages
File Size : 44,24 MB
Release : 1981
Category : Astronautics
ISBN :

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A survey of data from the first year of the P78-2 SCATHA satellite operations showed that a highest level spacecraft frame charging (phi sub f) both in sunlight ( -340 V) and in eclipse (> -8 kV) occurred on 24 April 1979. Analysis of the data indicates that if the sunlight charging environment had been present during eclipse, the vehicle would have charged in excess of 15 kV which is above any known charging level observed to date for the SCATHA satellite. Therefore, the environment at the peak of the sunlight charging at approx. 0650 UT 24 April 1979 was chosen for this worst case study. The environment at this time is characterized by an injection of high energy (30-335 keV) electron fluxes whose combined current correlates with phi sub f with a correlation coefficient of 0.95. The fluxes were highly anisotropic, maximizing perpendicular to the magnetic field. The low energy (

Author : Joan Feynman
Publisher :
Page : 213 pages
File Size : 28,82 MB
Release : 1981
Category :
ISBN :

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Problems pertaining to spacecraft charging at near-geosynchronous orbit were investigated using data from P78-2 SCATHA collected in 1979-80. These studies included specification of significant aspects of the near-geosynchronous environment, effectiveness of active control systems and verification of computer modeling of satellite potentials. Environmental specification studies were made of major plasma sheet boundaries, near-geosynchronous particle fluxes and long term prediction of hazardous geomagnetic conditions. Work was begun on magnetospheric modeling. Unfortunately, the particle beam active control system caused the failure of two instruments. These events were thoroughtly studied but some uncertainty remains concerning the causes of the problems. Comparisons of spacecraft discharge techniques indicated the x sub e (+) plasma source was the preferred operational mode. Satisfactory agreement with observed charging levels was obtained when the NASCAP/AFGL computer model was used with environmental input derived from observed particle fluxes. A secondary research effort focused on studies of ionosphere-magnetosphere interactions in the polar cap and auroral zone. Air Force measurements of S3-2 electric and magnetic fields and electron and thermal plasma fluxes were used as well as DMSP auroral imagery.

Author : C. P. Pike
Publisher :
Page : 918 pages
File Size : 13,61 MB
Release : 1977
Category : Plasma (Ionized gases)
ISBN :

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A Spacecraft Charging Technology Conference, sponsored by the USAF and NASA, was held in October 1976. The Proceedings contain over 50 papers dealing with subjects including: (1) the geosynchronous plasma environment, (2) spacecraft modeling, (3) spacecraft materials characterization, (4) spacecraft materials development, (5) satellite design and test. In addition, an executive summary and the transcript of a panel discussion are included. (Author).

Author :
Publisher :
Page : 9 pages
File Size : 38,40 MB
Release : 2006
Category :
ISBN :

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We present the results of a statistical study on high-level (above -200V in magnitude) negative-voltage spacecraft charging in eclipse at geosynchronous altitudes. Theoretically, there exists a critical temperature T* for a surface material. Below T*, no spacecraft charging occurs. Since T* depends on the surface material, which differs from satellite to satellite, each is expected to have its own critical temperature. The theoretical results are compared with the coordinated space-environmental parameter data obtained by the Los Alamos National Laboratory (LANL) geosynchronous satellites. The LANL data include spacecraft charging events measured on several geosynchronous satellites, in eclipse and in sunlight, over several years. We have found a nearly linear trend, or better described by a quadratic one, between the spacecraft potential and the ambient electron temperature for potentials below in magnitude of about -5kV. Extrapolation of the linear trend to zero volts shows an intercept at a finite temperature which agrees reasonably well with the critical temperature predicted by theory. The existence of a critical electron temperature is useful for informing decision and operational support of geosynchronous spacecraft with enhanced knowledge.