Electrostatic charging of the sunlit hemisphere of the Moon under different plasma conditions

Accounting for the continuous interaction of the solar radiation, the development of electrostatic charge on the sunlit lunar regolith under extreme plasma conditions has been investigated-the ambient plasma around Moon corresponds to the plasma parameters associated with the solar wind, wake region, SEP events, and terrestrial magnetosphere. The photoemission of electrons from the lunar surface corresponding to the solar radiation spectrum, electron energy-dependent secondary electron emission and simultaneous collection of the ambient non-Maxwellian plasma electrons/ions have been considered the dominant charging mechanisms. The lunar surface potential has been derived using the dynamical balance of the photoemission and plasma accretion currents over its surface-the potential dependence of the charging currents has consistently been accounted for. In results, the lunar surface potential dependence on the plasma, surface, and radiation parameters have been parametrically derived. For the high temperature plasma composition, the sunlit locations over the lunar surface are predicted to acquire a negative potential. The outcome infers that depending on topography and location along with realistic plasma/surface parameters, the lunar surface may hold significant contrast in charging, and it may differ by the orders of magnitude. Such disparity in the surface charging may act as a source of the transport of charged dust and local atmospheric charge (ions/electrons) over the lunar regolith.