高能电子辐照绝缘厚样品的表面电位动态特性∗

摘要

The surface potential and electron yield dynamic characteristics of an insulating thick sample under high-energy electron beam irradiation are obtained by combining the numerical simulation and experimental measurement. The numerical model takes into account the electron scattering, charge trapping, and charge transport. The results show that due to the electron scattering and transport, the space charge is weakly positive in the near surface and strongly negative inside sample; along the depth direction, the space potential decreases to a minimum value slowly, and then increases gradually and finally tends to zero; with the electron beam irradiation, the surface potential decreases to the negative kV magnitude gradually, and the total electron yield gradually increases to a stable value that is slightly less than unity. After stopping irradiation, the surface potential increases gradually, but charges are not eliminated completely. The surface potential decreases linearly with the increase of the beam energy, and increases with the increase of the incident angle, however it decreases slightly with the increase of the sample thickness.%采用数值计算和实验测量相结合的方法，阐明了高能电子束照射下绝缘厚样品的表面电位和电子产额动态特性。结果表明：由于电子在样品内部的散射和输运，沿着深度方向，空间电位先缓慢下降到最小值，然后逐渐升高并趋近于零；随着电子束照射，样品的表面电位逐渐下降，可至负千伏量级，电子总产额逐渐增大至一个接近于1的稳定值；电子束停止照射后，长时间放置下，表面电位将逐渐升高，但带电并不会消除；表面电位随电子束能量的升高近似线性下降，随入射角的增大而升高，而随样品厚度的增大仅略有下降。