Characteristics Of Moon Photoelectron Coupled With Secondary Electron Emission

Nowadays,the global environmental problems are serious and energy resources are overused,people are facing serious industrial pollution,lack of resources and other issues.In order to the Earth and Human beings can continue to survive,people will turn to the vast space,especially the Moon because it is the closest to the Earth.Recently people will send spacecraft and other equipment to detect the surface of the Moon,but when Spacecraft and other devices detect the Moon,these devices often occur the local parts failure,thermal control system failure caused by heat,etc.,the main cause of these failures is the Moon surface environment.First,as the Earth,the Moon surface would be affected by the Solar wind and Sunlight from the sun.The Solar wind have light impact on Earth surface,because of the Earth's magnetic field and the Earth's atmosphere,however,the Moon surface have no the atmosphere and the magnetic field is very small,Solar wind would have a significant effect on the Moon surface,especially the Solar wind and Sunlight would have an impact on the Moon surface electric field,so under the combined effect of the Solar wind and Sunlight,the electric field of the Moon surface is relatively complex.The sheath formed on the Moon surface is the main form of the Moon surface electric field.The study of the sheath parameters formed on the Moon surface is the basis for further study of the Moon environment.The Moon soil almost covers the entire Moon surface.The main component of the Moon soil is silicate.The total secondary electron emission coefficient of the silicate is relatively large.Even when the electron temperature is 1eV,the total secondary electron emission coefficient is almost 0.5.The total secondary electrons on the Moon surface cannot be ignored.In this paper,based on the total secondary electron emission coefficient and the total secondary electron emission spectrum distribution from the experimental data,combined with the actual parameters of the Moon surface,the total secondary electron emission model of the Moon soil well be established,combined with the Monte Carlo simulation and we can obtain the total secondary electron distribution on the Moon surface.Then,the one-dimensional steady-state sheath model of the dayside of the Moon and the shadow of the Moon will be established respectively.The expression of the dayside of the Moon and the shadow of the Moon will be obtained.The Matlab program was written and the combined with the illustration method,then we can obtain the sheath parameters under the action of the secondary electron coupled with photoelectrons.The results show that the total secondary electron distribution in the vertical direction of the Moon surface follows the three-temperature Maxwellian distribution.This conclusion solves the problem that the one-dimensional steady-state sheath model of the total secondary electron distribution cannot be determined on the Moon surface.The results show that there is no analytical solution of the sheath potential near the equator,however,with the decrease of the incident angle of the sunlight,the analytical solution of the sheath potential appears near the poles.In this paper,the incident angle of sunlight is further reduced,the photoelectron density decreases,the effect of photoelectrons in the sheath is reduced,and the sheath is near the poles of the Moon,and the analytical solutions of the sheath potential exists.It is found that the analytical solutions of the sheath have more than one solution,but there is only one true solution of the sheath potential.