Study On The Oscillation Characteristics Of The Lunar Sheath And Charged Lunar Dust Motion

As the nearest celestial body to the Earth,the moon plays an important role in the human exploration of space.The human spacecraft will explore the further space by using the moon as a springboard.However,the complex environment of the lunar surface has posed a huge challenge to the lunar exploration activities of mankind.In particular,the impact of the special electric field environment on the lunar surface is obvious.The electric field will not only affect the lunar device directly,but also lead to lunar dust levitations,and cause difficulties for the human activities.At present,the study of the electric field environment on the lunar surface and the research on the charge and discharge of the lunar dust and the movement are based on the assumption that the sheath structure of the lunar surface is a steady-state structure,without considering the influence of the time.However,the structure is not stable,which maybe influence the movement of the charged lunar dust.The research about stability of the sheath structure and its influence on the charged dust movement helps to understand the rules of the lunar surface electric field and the charged dust motion more deeply.Provide a reference to reduce the influence caused by the moon surface electric field environment and the suspended moon dust on the lunar exploration activities.According to the needs of plasma numerical simulation,a numerical simulation program based on IFE-PIC theory was programmed.The PIC part is used to simulate the single particle dynamics,and the IFE theory is used to solve the electric field distribution under complex interface conditions.Validate the key parts of the program,confirm the correctness of the numerical simulation program.Under the influence of time,the sheath was numerically simulated and the oscillation of the sheath was observed.Controlled numerical simulation was conducted to study the effect of numerical models such as time step,simulated area size,mesh size and boundary conditions.The results show that the change of parameters will not influence the correctness of the conclusion,and excludes the possibility of observed phenomenon is numerical oscillations caused by the numerical model itself.Through analysis,we found the sheath potential oscillation frequency coincides with the plasma frequency,it is considered that the sheath oscillation is caused by the plasma oscillation.The statistical analysis of charge density,electron density,ion density,deposited charge density,number of incident particles further confirms the correctness of the conclusion.At the same time,the influence of photoelectrons on the sheath structure was studied.It was found that the larger the photoelectron density,the larger the amplitude of the sheath oscillation,but the same frequency.Simulated the charged lunar dust motion under the oscillating sheath,study the charge and discharge of the dust on the oscillating sheath and the law of motion,the results show that the lunar dust motion in the oscillating sheath will be influenced by the radius,initial potential and sheath structure.