LAUSR

A photoelectron sheath couples with positively charged floating fine dust to constitute a two-component dusty plasma over the sunlit locations on the Moon—the possibility of small amplitude nonlinear dust acoustic (DA) excitations in this plasma environment is investigated. The standard reductive perturbation approach has been adopted to analyze the nonlinear evolution of photoelectron-dust plasma dynamics, including the equations for dust fluid continuity and momentum, plasma potential (Poisson equation), and nonadiabatic dust charge variation. The photoemission from and photoelectron accretion on dust particles are considered dominant charging mechanisms where Fowler's formulation for the photoemission from the positively charged spherical dust and non-Maxwellian nature of the sheath photoelectrons are consistently accounted for. The dust charge variation induces collisionless dissipation, which damps amplitude and reduces the velocity of propagating DA waves. Under typical solar irradiation conditions, the nonlinear analysis of the sunlit lunar dusty plasma is supposed to support DA solitary and DA shock wave structures of both rarefied and compressive nature; the dominance of dispersion and dissipation effects in the fluid dynamics is shown to exhibit oscillatory and monotonic shock waves, respectively. The passage of such nonlinear DA structures might energize the ambient charged dust and photoelectrons locally and could be an important mechanism for energy/particle transport in the vicinity of the sunlit locations over the Moon.