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

Sarno-Smith LK, Larsen BA, Skoug RM, Liemohn MW, Breneman A, Wygant JR, Thomsen MF - Space Weather (2016)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Climate and Space Engineering University of Michigan Ann Arbor Michigan USA.

ABSTRACT

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.

No MeSH data available.


Related in: MedlinePlus

The negative spacecraft potential measured by EFW and extracted from the HOPE H+ line at the same times from February 2013 to April 2015. The diameter of each point is the width of the HOPE energy channel bin (15% of the measured energy) corresponding to that measurement. The purple line is the exponential fit for scatter points within one standard deviation of where EFW ϕ = HOPE ϕ.
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swe20312-fig-0006: The negative spacecraft potential measured by EFW and extracted from the HOPE H+ line at the same times from February 2013 to April 2015. The diameter of each point is the width of the HOPE energy channel bin (15% of the measured energy) corresponding to that measurement. The purple line is the exponential fit for scatter points within one standard deviation of where EFW ϕ = HOPE ϕ.

Mentions: Figure 6 compares the magnitude of charging measured by EFW and determined by the HOPE extraction method at times when both had measurements. The diameter of each point gives the width of the HOPE ion line energy channel. The blue dotted line shows the exponential fit of scatter points within one standard deviation of where EFW = HOPE data. For an exponential fit y = AeB, where A was 1.14 and B was 0 .94, confirming that HOPE measures higher potentials. In Figure 6, we can observe that the HOPE extracted ion line measures a higher negative spacecraft potential than EFW particularly during intense charging events, even with error bars taken into account. This is supported by the exponential fit having a slope > 1.


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

Sarno-Smith LK, Larsen BA, Skoug RM, Liemohn MW, Breneman A, Wygant JR, Thomsen MF - Space Weather (2016)

The negative spacecraft potential measured by EFW and extracted from the HOPE H+ line at the same times from February 2013 to April 2015. The diameter of each point is the width of the HOPE energy channel bin (15% of the measured energy) corresponding to that measurement. The purple line is the exponential fit for scatter points within one standard deviation of where EFW ϕ = HOPE ϕ.
© Copyright Policy - creativeCommonsBy-nc-nd
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4933096&req=5

swe20312-fig-0006: The negative spacecraft potential measured by EFW and extracted from the HOPE H+ line at the same times from February 2013 to April 2015. The diameter of each point is the width of the HOPE energy channel bin (15% of the measured energy) corresponding to that measurement. The purple line is the exponential fit for scatter points within one standard deviation of where EFW ϕ = HOPE ϕ.
Mentions: Figure 6 compares the magnitude of charging measured by EFW and determined by the HOPE extraction method at times when both had measurements. The diameter of each point gives the width of the HOPE ion line energy channel. The blue dotted line shows the exponential fit of scatter points within one standard deviation of where EFW = HOPE data. For an exponential fit y = AeB, where A was 1.14 and B was 0 .94, confirming that HOPE measures higher potentials. In Figure 6, we can observe that the HOPE extracted ion line measures a higher negative spacecraft potential than EFW particularly during intense charging events, even with error bars taken into account. This is supported by the exponential fit having a slope > 1.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Climate and Space Engineering University of Michigan Ann Arbor Michigan USA.

ABSTRACT

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.

No MeSH data available.


Related in: MedlinePlus