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Found 3 entries in the Bibliography.

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Determining plasmaspheric density from the upper hybrid resonance and from the spacecraft potential: How do they compare?

The plasmasphere is a critical region of the magnetosphere. It is important for the evolution of Earth\textquoterights radiation belts. Waves in the plasmasphere interior (hiss) and vicinity (EMIC, chorus) help control the acceleration and loss of radiation belt particles. Thus, understanding the extent, structure, content, and dynamics of the plasmasphere is crucial to understanding radiation belt losses. The Van Allen Probes mission uses two methods to determine the total plasma density. First, the upper hybrid resonance (UHR) frequency can provide electron density; this determination is the most accurate and robust. However, it requires significant analysis and is challenging during geomagnetically active times: it becomes difficult to interpret the wave spectrum, and the amount of available data is severely limited. Second, the spacecraft potential is a proxy for the plasma density. These high resolution measurements are available with high duty cycle. However, environmental effects can limit the accuracy of this method. The relation between spacecraft potential and density is empirical, requiring an independent density measurement and repeated checks. We perform a quantitative comparison of these two in situ techniques during the first 3.5 years of the Van Allen Probes mission. We show how to calibrate potential-based density measurements using only publicly available wave-derived densities to provide high fidelity results even if upper hybrid measurements are sparse or unavailable. We quantify the level of uncertainty to expect from potential-derived density data. Our approach can be applied to any in situ spacecraft mission where reliable absolute density and spacecraft potential data are available.

Jahn, J.-M.; Goldstein, J.; Kurth, W.S.; Thaller, S.; De Pascuale, S.; Wygant, J.; Reeves, G.D.; Spence, H.E.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 01/2020

YEAR: 2020     DOI: 10.1029/2019JA026860

cold plasma density; plasmasphere; spacecraft charging; Van Allen Probes; wave resonances

Space weather effects and prediction

Adverse conditions in the space environment, that is, space weather, can affect the performance and reliability of space-borne and ground-based technological systems. The dynamic near-Earth space environment, driven by solar activity, exhibits large variations of energetic particles, plasma, and electromagnetic fields. Abrupt changes or enhancements in these may cause disruption of satellite operations, communications, and electric power grids, leading to a variety of economic losses and impacts on our security. This chapter describes various space weather effects related to energetic particle populations in the inner magnetosphere during geomagnetic storms. Among the most important of these effects are geomagnetically induced currents (GICs) and spacecraft charging. GICs are due to time varying magnetic fields at the Earth’s surface produced by the spatial and time variable electric currents flowing in the ionosphere and magnetosphere during geomagnetic disturbances. Spacecraft surface charging is due to moderate-energy electrons depositing their charge on spacecraft surfaces and driving potential differences, which can lead to discharges that can damage material and electronics. Spacecraft internal (or “deep dielectric”) charging is due to highly energetic electrons that can penetrate through spacecraft shielding and can damage sensitive subsystems or even cause failure of the entire space system. Recent advances in our understanding of these space weather effects and capabilities for their nowcast and forecast are presented.

Roeder, James; Jordanova, Vania;

Published by: Ring Current Investigations The Quest for Space Weather Prediction      Published on:

YEAR: 2020     DOI: 10.1016/B978-0-12-815571-4.00008-1

spacecraft charging; electrostatic discharges; geomagnetically induced currents; electrical power systems; Van Allen Probes


Spacecraft surface charging within geosynchronous orbit observed by the Van Allen Probes

Using the Helium Oxygen Proton Electron (HOPE) and Electric Field and Waves (EFW) instruments from the Van Allen Probes, we explored the relationship between electron energy fluxes in the eV and keV ranges and spacecraft surface charging. We present statistical results on spacecraft charging within geosynchronous orbit by L and MLT. An algorithm to extract the H+ charging line in the HOPE instrument data was developed to better explore intense charging events. Also, this study explored how spacecraft potential relates to electron number density, electron pressure, electron temperature, thermal electron current, and low-energy ion density between 1 and 210 eV. It is demonstrated that it is imperative to use both EFW potential measurements and the HOPE instrument ion charging line for examining times of extreme spacecraft charging of the Van Allen Probes. The results of this study show that elevated electron energy fluxes and high-electron pressures are present during times of spacecraft charging but these same conditions may also occur during noncharging times. We also show noneclipse significant negative charging events on the Van Allen Probes.

Sarno-Smith, Lois; Larsen, Brian; Skoug, Ruth; Liemohn, Michael; Breneman, Aaron; Wygant, John; Thomsen, Michelle;

Published by: Space Weather      Published on: 02/2016

YEAR: 2016     DOI: 10.1002/2015SW001345

EFW; HOPE; spacecraft charging; surface charging; Van Allen Probes