| Lunar exploration is one of the hot spot in deep space exploration, while measurement of lunar magnetic field is basic and key mission of it.In this paper, I present lunar crustal field and surface potential on the Moon in detail first, then describe the status and importance of measurement on crustal magnetism. I also introduce the electron reflectometry technique which is a method makes use of the fact that electrons behave adiabatically in the lunar environment and reflect from regions of increased magnetic field, the so-called magnetic mirror effect.I studied the effect of surface potential on solar wind electrons reflected by the lunar crustal magnetic field through analyzing the reflectivity and distributions under different conditions. My calculations and simulations showed that the variations of magnetic field and surface potentials play important roles in changing trajectories of electrons. Furthermore, the changes caused by these two variations can be distinguished from each other through further analysis of the results.1) Effect due to change of dipole moment is overall and energy independent;2) Effect due to electric field covers the whole area and is energy dependent and weakens with the magnitude.Thus, we could infer the existence and magnitude of surface potentials from the comparison distributions of up-going with that of down-going. Both the magnitude of crustal field and potential can be acquired from the data of successful launched satellites such as Lunar Prospector.There are not always surface potentials on the Moon, so we could analyse data under different conditions and get the more precise results. But we also need consider an important circumstance that the craft would be charged in the lunar environment. How to eliminate the impress and get a more precise result are important for us in the future work. This finding could also help to design and to develop new devices in the coming lunar programs.
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