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The Plasma Wake Downstream of Lunar Topographic Obstacles: Preliminary Results from 2D Particle SimulationsAnticipating the plasma and electrical environments in permanently shadowed regions (PSRs) of the moon is critical in understanding local processes of space weathering, surface charging, surface chemistry, volatile production and trapping, exo-ion sputtering, and charged dust transport. In the present study, we have employed the open-source XOOPIC code [I] to investigate the effects of solar wind conditions and plasma-surface interactions on the electrical environment in PSRs through fully two-dimensional pattic1e-in-cell simulations. By direct analogy with current understanding of the global lunar wake (e.g., references) deep, near-terminator, shadowed craters are expected to produce plasma "mini-wakes" just leeward of the crater wall. The present results (e.g., Figure I) are in agreement with previous claims that hot electrons rush into the crater void ahead of the heavier ions, fanning a negative cloud of charge. Charge separation along the initial plasma-vacuum interface gives rise to an ambipolar electric field that subsequently accelerates ions into the void. However, the situation is complicated by the presence of the dynamic lunar surface, which develops an electric potential in response to local plasma currents (e.g., Figure Ia). In some regimes, wake structure is clearly affected by the presence of the charged crater floor as it seeks to achieve current balance (i.e. zero net current to the surface).
Document ID
20110007999
Acquisition Source
Goddard Space Flight Center
Document Type
Other
Authors
Zimmerman, Michael I.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Farrell, W. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Snubbs, T. J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Halekas, J. S.
(NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 25, 2013
Publication Date
January 1, 2011
Subject Category
Geophysics
Distribution Limits
Public
Copyright
Public Use Permitted.
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