709 / 2022-03-31 16:51:57

Surface charging characteristics of polymer medium under electron beam

surface charge accumulation,polymer,electron beam

Purpose/Aim

The operating space environment of spacecraft is complex and changeable. The interaction between space charged particles and spacecraft leads to electrostatic charging and discharging effect, which causes in-orbit fault of spacecraft. Polymer materials are widely used in spacecraft components for their excellent thermal stability and good dielectric properties. In this paper, the surface charging characteristics of polymer medium are investigated to explore the charging effect mechanism and related parameter characteristics of spacecraft in space environment.

Experimental/Modeling methods

For simulation, considering the ballistic transport, drift diffusion of electrons and holes in the medium charging process, as well as the combination and trapping process in the medium, the self-consistent electron transport drift diffusion model of polymer medium charging under the action of electron beam is established. For experiment, based on the electron gun charging platform, the polymer medium charging experiment is carried out. By changing the experimental parameters (electron gun energy, beam current; medium type, thickness, etc.), the variation law of medium surface potential and leakage current is obtained, and the influence of different parameters on polymer medium surface charging effect is explored.

Results/discussion

Under the bombardment of low energy electron beam, the internal charge of dielectric material is mainly distributed on the surface and presents a negative-positive-negative distribution. The amount of positive charge is only slightly higher than that of negative charge, resulting in a relatively small surface potential. Under the bombardment of high-energy electron beam, the current gradually tends to be distributed in the near surface region with the increase of time. The internal charge distribution of the material is basically negative charge, and the surface potential of the medium decreases gradually and finally reaches saturation. The electron gun beam density and dielectric thickness have a certain influence on the charging effect.

Conclusions

To sum up, factors such as types, thickness and surface condition of polymer medium, electron energy, beam density, temperature and so on have certain influence on surface charging phenomenon of polymer medium. The experimental results are basically consistent with the simulation results.