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Dependence of Lunar Surface Charging on Solar Wind Plasma Conditions and Solar IrradiationThe surface of the Moon is electrically charged by exposure to solar radiation on its dayside, as well as by the continuous flux of charged particles from the various plasma environments that surround it. An electric potential develops between the lunar surface and ambient plasma, which manifests itself in a near-surface plasma sheath with a scale height of order the Debye length. This study investigates surface charging on the lunar dayside and near-terminator regions in the solar wind, for which the dominant current sources are usually from the pohotoemission of electrons, J(sub p), and the collection of plasma electrons J(sub e) and ions J(sub i). These currents are dependent on the following six parameters: plasma concentration n(sub 0), electron temperature T(sub e), ion temperature T(sub i), bulk flow velocity V, photoemission current at normal incidence J(sub P0), and photo electron temperature T(sub p). Using a numerical model, derived from a set of eleven basic assumptions, the influence of these six parameters on surface charging - characterized by the equilibrium surface potential, Debye length, and surface electric field - is investigated as a function of solar zenith angle. Overall, T(sub e) is the most important parameter, especially near the terminator, while J(sub P0) and T(sub p) dominate over most of the dayside.
Document ID
20160005752
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Stubbs, T. J.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Farrell, W. M.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Halekas, J. S.
(California Univ. Berkeley, CA, United States)
Burchill, J. K.
(Calgary Univ. Alberta, Canada)
Collier, M. R.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Zimmerman, M. I.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Vondrak, R. R.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Delory, G. T.
(California Univ. Berkeley, CA, United States)
Pfaff, R. F.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
May 3, 2016
Publication Date
January 1, 2014
Publication Information
Publication: Planetary and Space Science
Publisher: Elsevier
Volume: 90
ISSN: 0032-0633
Subject Category
Plasma Physics
Report/Patent Number
GSFC-E-DAA-TN31412
Funding Number(s)
CONTRACT_GRANT: NNG07EK31C
Distribution Limits
Public
Copyright
Other
Keywords
Photoemission
Plasma
Moon

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