Dust dynamics in the lunar dusty plasmas: Effects of magnetic fields and dust charge variations

Abstract

The influence of the magnetic field of the Earth's magnetotail on dusty plasmas above the sunlit surface of the Moon is studied. For this purpose, a physical-mathematical model for a self-consistent description of dust grains and photoelectrons in the presence of the magnetic field is developed. Trajectories of motion of dust grains above the lunar surface are considered. It is shown that a distinguishing feature of the trajectory of a dust grain motion is the presence of oscillations. The process of damping of these oscillations is demonstrated to be related to variations of dust grain charges that is consistent with the concept of anomalous dissipation in dusty plasmas. We clarify whether dust grains in dusty plasmas above the sunlit lunar surface are “levitated” or “lofted.” The processes of dust grain charge variations are too fast in comparison with the day duration of the Moon. In this connection, for the majority of dust grains above the sunlit lunar surface, the oscillations are damped, and these grains can be considered as levitated. Only very fine grains do not go into “levitating” grain mode during the entire day on the Moon and can be treated as lofted those. A theory of dusty plasmas above the sunlit surface of the Moon, which takes into account the lunar gravity and the electrostatic processes but does not take into account the magnetic fields, explains the existence of dusty plasmas only for rather high lunar latitudes. The magnetic fields of the Earth's magnetotail are shown to provide a possibility of dust transport above the lunar surface, which can result in the existence of positively charged dust and correspondingly dusty plasmas at the sunlit side of the Moon for the whole range of the lunar latitudes.

Plasma Sheath around Chandrayaan-3 Landing Site: A Case Study

“…It ignores the effect of the magnetic field considering its nominal magnitude and marginal effects on the charging currents. For instance, note that the Ch3 LS is not near the magnetic anomaly region, but the Moon encounters the Earth's magnetic field of the order of 10 −9 -10 −8 T as it passes through the magnetotail (Hones 1985;Harada 2015;Popel et al 2022). However, due to the large gyroradius around 1.5 and hundreds of kilometers of plasma electrons and ions, respectively, and the significantly smaller region of our interest, the effect of the magnetic field on the charging currents and hence the surface charge may be safely ignored (Mishra & Bhardwaj 2020).…”

Ion flow and dust charging at the sheath boundary in dusty plasma with an electron-emitting surface: applications to laboratory and lunar dusty plasmas

“…In recent years, lunar surface explorations, plasma-surface interactions, dust dynamics, and dust levitation have been keen interests of researchers for lunar research activities [34,[53][54][55]. However, the effect of the cut-off half-Maxwellian distribution of photoelectrons due to the negative surface potential on the Bohm sheath criterion and sheath characteristics is still lacking [56][57][58][59][60][61]. Poppe and Horányi performed a one-dimensional particle-in-cell simulation method to study the characteristics of photoelectron sheath and dust particle levitation.…”

Space plasma physics science opportunities for the lunar orbital platform - Gateway

“…Dust is another component of the lunar plasma environment (Stubbs et al, 2007;Grün et al, 2011;Horányi et al, 2015;Popel et al, 2018;Popel et al, 2022). Dust grains on (or near) the lunar surface can either be ejected from the regolith, due to the impact of interplanetary micrometeoroids, or be electrostatically levitated due to grain charging, as discussed in the previous paragraph.…”