太阳风电子在月表电磁场中的运动

月表磁异常区的分布是月球探测工程的重要内容. 但是由于月表电磁环境错综复 杂, 通常认为月球表面在特殊的空间天气条件下会带有数千伏电压. 以往的空间研究已经证实, 表面的带电与放电容易造成卫星仪器的异常或失联. 月表电场对电子 反射法有重要影响, 研究分析不同电磁条件下太阳风电子的运动轨迹,对月表环境 (电磁环境, 太阳风条件, 等离子体参数等)的研究可以更加深入细致. 通过模拟向月表运动的太阳风电子的运动轨迹, 分析了月表电磁环境的改变对太阳风电子反射 的影响, 并着重研究了月表电场对电子反射法遥感探测月表磁异常的影响, 为探测 月表电磁环境提供了重要的信息. 

Simulation of Electrons' Trajectories in the Lunar Electric and Magnetic Field

The increasing interest in lunar exploration requires a better understanding of environment at the lunar surface. Like any object in plasma, the surface of the Moon charges to an electric potential that minimizes the total incident current. Surface charging is an universal process affecting all airless regolith-covered bodies. However, there are still many details that remain unclear and need to be discussed to understand those possible processes such as ion sputtering and electrically-driven dust transport. There are also many subjects that require further study, such as the temporal and spatial variation of lunar surface charging. Simulation and analysis of trajectories of the electrons under different conditions would help to predict surface potential, which in turn would benefit the understanding of the lunar environment. In this paper, the solar wind electrons which are moving toward the moon surface are traced to study the effect of surface potential on solar wind electrons reflected by the lunar crustal magnetic field. Statistic of number of electrons that reflected under different conditions is also analyzed. The calculations and simulations show that the variation of either magnetic field or potential difference does play an important role in the changing traces of electrons. Furthermore, the changes by the variations could be told from analysis of the results. Thus, the magnitude of crustal field and potential could be inferred from the data of instrument of LP (Lunar Prospector satellite). New devices could also be designed or developed in the coming lunar projects. Surface potentials are not always present on the Moon, so we could collect and analyze data under different conditions and thus obtain more precise results. However, there is one more important circumstance needed to be considered that the craft would be charged in the lunar environment. How to eliminate the influence of charged craft and get a more precise result are important problems for us to explore in the future.