Solar cycle variations of the Cluster spacecraft potential and its use for electron density estimations

• Published in: Journal of Geophysical Research: Space Physics Vol. 117; no. A1
• Main Authors: Lybekk, B., Pedersen, A., Haaland, S., Svenes, K., Fazakerley, A. N., Masson, A., Taylor, M. G. G. T., Trotignon, J.-G.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01.01.2012; American Geophysical Union; American Geophysical Union/Wiley
• Subjects: Atmospheric sciences; Earth sciences; Earth, ocean, space; electron density; Exact sciences and technology; Irradiation; Magnetism; magnetosphere; Plasma; Satellites; Sciences of the Universe; Scientific apparatus & instruments; Solar cycle; solar EUV radiation; Solar radiation; Spacecraft; spacecraft potential; Ultraviolet radiation; Maximum solar activity; Photoelectron; CLUSTER satellite; Plasma; Minimum solar activity; Eddying current; Space remote sensing; Satellite observation; solar radiation; Plasma density; electrons; irradiation; Polar Cap; instruments; balance; Vacuum ultraviolet radiation; solar cycles; Magnetospheric tail; electron density; calibration
• ISSN: 0148-0227; 2169-9380; 2156-2202; 2169-9402
• DOI: 10.1029/2011JA016969

A sunlit conductive spacecraft, immersed in tenuous plasma, will attain a positive potential relative to the ambient plasma. This potential is primarily governed by solar irradiation, which causes escape of photoelectrons from the surface of the spacecraft, and the electrons in the ambient plasma providing the return current. In this paper we combine potential measurements from the Cluster satellites with measurements of extreme ultraviolet radiation from the TIMED satellite to establish a relation between solar radiation and spacecraft charging from solar maximum to solar minimum. We then use this relation to derive an improved method for determination of the current balance of the spacecraft. By calibration with other instruments we thereafter derive the plasma density. The results show that this method can provide information about plasma densities in the polar cap and magnetotail lobe regions where other measurements have limitations. Key Points Plasma density estimates from SC‐potentials varies with EUV during solar cycle