Distribution of charge on floating dust particles over sunlit locations on Moon

Abstract

Abstract The charging of fine particles within the photoelectron cloud is the key in characterizing the dusty plasma environment over sunlit locations. In this work, based on the statistical mechanics and charging kinetics of the floating dust particles within the photoelectron sheath over the sunlit lunar surface, the distribution of charge over floating particles has been investigated. The natural randomization of the dust charging currents, the anisotropy in sheath photoelectron population and electric field/ potential, and half Fermi Dirac velocity distribution of the emitted photoelectrons have been consistently accounted for in the formulation. In this framework, due to natural fluctuation, the charge on the floating dust particles is shown to be distributed over a wide range (∼100 e). This random fluctuation in charge might alter the static equilibrium of the floating dust particles and induce an altitudinal fluctuation (∼10%) about its mean position within the sheath. The concept and results suggest that the natural fluctuation of the dust charge could be a reason that the strict dust levitation under static force equilibrium is less likely to exhibit over the sunlit lunar surfaces. This effect of dust charge and subsequent altitudinal fluctuations have been found pronounced at larger latitudes (near the terminator region) and higher lunar altitudes.