Steady‐State Solution of a Solar Wind‐Generated Electron Cloud in a Lunar Crater. Issue 7 (22nd July 2019)

• Record Type: Journal Article
• Authors: Rhodes, Dov J.; Farrell, W. M.
• Is Part Of: Journal of geophysical research. Volume 124:Issue 7(2019)
• Page Start: 4983
• Page End: 4993
• Publication Date: 2019-07-22
• Subjects: plasma wake -- electron cloud -- lunar surface -- nonneutral plasma -- plasma surface interaction -- plasma expansion; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2019JA026625
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: We formulate an analytic description of a steady‐state electron cloud and affiliated surface charge, formed in the plasma wake generated as the solar wind flows horizontally over a lunar crater. The solution is complementary to the well‐known self‐similar plasma expansion formulation, which breaks down at the plasma wake front and thus fails to capture a substantial region of the crater interior. The present model establishes a theoretical basis for existing simulation results, which suggest that the cavity formed below the wake front is populated mainly by electrons, resulting in a substantial negative surface charge. The electrostatic potential throughout this subwake region is determined by solving Poisson's equation for a Maxwellian electron cloud, bounded above by the self‐similar plasma expansion front and below by the electrostatically charged surface. Key Points: We derive an analytic formulation of the electron cloud surface charge associated with the solar wind plasma wake at a lunar crater New boundary conditions for plasma expansion provide physical insight into the steady‐state condition near the lunar surface The solution describes a unique nonneutral electrical environment in shadowed regions of the Moon