Simulation Experiment Of Plasma Mixed With Photoelectron

Spacecraft and lunar exploration equipment always exposure to lunar environment. The electric field will become very complex by the influence of the solar wind and ultraviolet light. The charged dust suspended in the lunar environment, it is very easy to cause a series of problems, such as the contamination of aerospace equipment, communication failures. So, the electric field is essential for modern aerospace technology. There are different ways to study the lunar sheath, such as theoretical modeling, numerical analysis, the satellite observations. But the modeling and the numerical analysis can’t consider all the factors, the satellite observations spend too much and the observation area is also restricted. So we simulate the experiment to study the photoelectric sheath.There is a certain limit for experiment on the ground. It can’t reflect the real structure of the lunar sheath. We can only simulate the sheath approximately to make the plasma environment as thin as possible. The integrity of the structure can’t be affected during the simulation. We can obtain the parameters from the experimental diagnosis. According to the result of matlab calculation and the PIC simulation program, We can camplete the analysis of the experimental data.In order to research the features of the photoelectron sheath, this paper set up the experiment based on the requirements of the plasma environment, namely the plasma environment should be as thin as possible and can’t affect the integirty of the sheath. We simulate the plasma environment and use the Langmuir single probe diagnostic the parameters of the plasma. Then we simulate the sheath structure in the vacuum chamber and measure the electric potential distribution in the sheath. According to the result of matlab calculation and the PIC simulation program, we analyze the the classical sheath. We bring in the photoelectric material and UV light source base on the classic sheath experiment. We simulate the photoelectron sheath and use the Langmuir emitting probe diagnostic the parameters of the sheath.The experimental results show that the classic sheath, namely no photoelectron cases, the result of simulation can coincide with the experimental very well. But in the photoelectron sheath, we find that they have a large deviation. We analyze the reason based on matlab calculation and the PIC simulation program, and point out that the different density of plasma between the lunar and the experiment environment makes such deviation. The collision effect of different particle in experimental sheath causes the differences.