Statistical properties of the surface‐charging environment at geosynchronous orbit

Thomsen, M. F.; Henderson, M. G.; Jordanova, V. K.

doi:10.1002/swe.20049

Cited by 73 publications

(98 citation statements)

References 26 publications

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“…It has been established that the high flux of electrons with energies E ≥ 10 keV is the main factor leading to the hazardous level of surface charging (e.g Thomsen et al, 2013;Ferguson et al, 2015;Matéo-Vélez et al, 2018). It has been established that the high flux of electrons with energies E ≥ 10 keV is the main factor leading to the hazardous level of surface charging (e.g Thomsen et al, 2013;Ferguson et al, 2015;Matéo-Vélez et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

On the Accuracy of Reconstructing Plasma Sheet Electron Fluxes From Temperature and Density Models

2019

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The particle simulations of the inner magnetosphere require time-dependent boundary conditions for the particle flux set in the transition region between dipolar and tail-like configurations. Usually, the flux is reconstructed from particle density and temperature predicted by empirical models or magnetohydrodynamic simulations. However, this method requires assumptions about the energy spectra to be made. This uncertainty adds to the inaccuracy of the empirical models or magnetohydrodynamic predictions. We use electron flux measurements in the nightside at r = 6-11R E in the 1-300 keV energy range to estimate the potential accuracy of the electron flux reconstruction from the macroscopic plasma parameter models. We use kappa and Maxwellian distribution functions as well as two population approximations to describe the electron spectra. It is found that this method works reasonably well in the thermal energy range (1-10 keV). However, the average difference between measured and predicted fluxes becomes as large as 1 order of magnitude at energies ≥40 keV. The optimal value of the kappa parameter is found to be between 3 and 4, but it depends strongly on magnetic local time and radial distance. We conclude that the development of the flux-based models (model of differential flux at several reference energies) instead of density and temperature models can be considered as a promising direction.

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Section: Discussionmentioning

confidence: 99%

On the Accuracy of Reconstructing Plasma Sheet Electron Fluxes From Temperature and Density Models

2019

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“…Along with the electron and ion fluxes, the MPA instruments also measure the electrostatic surface potential on the LANL spacecraft, relative to the ambient plasma [ Thomsen et al ., ]. Depending on their individual design and construction details, spacecraft can charge positive or negative [ DeForest , ; Garrett , ; Farthing et al ., ; Lanzerotti et al ., ; Thomsen et al ., ]. In the case of the LANL satellites, the greatest level of charging occurs during hours of eclipse when the surface potential can reach thousands of volts (negative) with respect to the ambient plasma.…”

Section: Comparison Of Model Predictions With Observationsmentioning

confidence: 99%

An improved empirical model of electron and ion fluxes at geosynchronous orbit based on upstream solar wind conditions

et al. 2016

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A new empirical model of the electron fluxes and ion fluxes at geosynchronous orbit (GEO) is introduced, based on observations by Los Alamos National Laboratory (LANL) satellites. The model provides flux predictions in the energy range ~1 eV to ~40 keV, as a function of local time, energy, and the strength of the solar wind electric field (the negative product of the solar wind speed and the z component of the magnetic field). Given appropriate upstream solar wind measurements, the model provides a forecast of the fluxes at GEO with a ~1 h lead time. Model predictions are tested against in‐sample observations from LANL satellites and also against out‐of‐sample observations from the Compact Environmental Anomaly Sensor II detector on the AMC‐12 satellite. The model does not reproduce all structure seen in the observations. However, for the intervals studied here (quiet and storm times) the normalized root‐mean‐square deviation < ~0.3. It is intended that the model will improve forecasting of the spacecraft environment at GEO and also provide improved boundary/input conditions for physical models of the magnetosphere.

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“…This is suggestive that 9 keV might be close to the best E min for LANL satellites. Thomsen et al [21] have analyzed many years of LANL data, and Fig. 26 here is their Fig.…”

Section: Lanl Geo Satellites (Spinners)mentioning

confidence: 99%

Best Geosynchronous Earth Orbit Daytime Spacecraft Charging Index

Ferguson

Hilmer

Davis

2015

Journal of Spacecraft and Rockets

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Recently, the debate on what is the best daytime Geosynchronous Earth Orbit spacecraft charging index has been reopened. In this paper, the conclusions of one of the recent papers on the subject are verified by comparing Nascap-2k results with charging and fluxes measured on the Spacecraft Charging at the High Altitudes, Intelsat, Defense Satellite Communications System, and Los Alamos National Laboratory Geosynchronous Earth Orbit satellites. In addition, a refined measure of charging is presented as the total thermal electron flux above a certain minimum energy that is well above the second crossover point in secondary electron emission. The use of this type of index is justified by correlations between Nascap-2k simulation results and total fluxes above a range of energies. The best minimum energy to use is determined for spacecraft of different design and surface materials. Finally, the optimum Geosynchronous Earth Orbit daytime spacecraft charging index is obtained, and its use for predicting and resolving spacecraft anomalies in real time is justified.

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Statistical properties of the surface‐charging environment at geosynchronous orbit

Cited by 73 publications

References 26 publications

On the Accuracy of Reconstructing Plasma Sheet Electron Fluxes From Temperature and Density Models

On the Accuracy of Reconstructing Plasma Sheet Electron Fluxes From Temperature and Density Models

An improved empirical model of electron and ion fluxes at geosynchronous orbit based on upstream solar wind conditions

Best Geosynchronous Earth Orbit Daytime Spacecraft Charging Index

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