The Dynamics Analysis Of Chargedparticles In The Electric Field Of Lunar Surface

Lunar surface environment is very complex, which proposes a challenge to the working reliabilit y of lunar spacecraft and instruments on the moon. Under the effect of the electric field, lunar dust is charged and suspended, then lead to surface wear, mechanical obstruction, reading errors and other mistakes o f spacecraft and lunar exploration instrument. Thus in order to find a favorable place for landing and to ensure the lunar spacecraft work well, it’s important to master the surface electric field of the moon, and how it effect the lunar dust.Lunar dust is widely present on the lunar surface. In this paper, we analyze the nature of lunar dust and obtain its charging mechanism, and establish the mathemat ical model of charging Orbital Motion Limited Theory(OML). The function of charging and the boundary conditions are obtained. By numerical simulation we obtain the main parameters which affect charging, as the mass of the electron is smaller than the ions, besides the thermal velocity is very larger, the electron reach the surface of dust sooner, so the potential of dust usually is negative.For the influence of the wake in the shadow of the moon, the electron distribution function is no longer meet s the Maxwell distribution, so the charging model on the dayside is no longer applicable. In this paper, we establish a new potential model of the lunar surface, and take the wake into consideration to expand the model to the nightside of the moon. The results show that with the solar zenith angle increase, the transition from the photon-driven posit ively charged surface to the electron-driven negatively charged surface occurs upstream of the terminator, and there exist a "dead zone" in the dayside of the moon, where no lofted dust.In order to study the electrostatic levitation phenomenon of lunar dust, in this paper, we establish a mathematical model of the plasma sheath and obtain 3 different structure of the plasma sheath. The movement of dust in different sheath is simulated with numerical simulation program based on PIC. The results show the major parameters which influence lofting: the solar zenith angle, size of dust, charge of dust and the sheath that dust belong to. Simulation results show that lunar dust are more likely to occur in the sunrise and sunset hours, in addition, the smaller of lunar dust is, the easier to be floated, and the height of dust floating in the classic sheath is bigger than those in saturation sheath.