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针对空间微放电效应中介质材料的带电状态对二次电子发射的复杂影响,文章采用数值模拟的方法,首次从带电平衡模式的角度研究了介质材料受电子照射后的二次电子动态发射特性。数值模拟模型结合了蒙特卡罗方法和时域有限差分方法,考虑了弹性和非弹性碰撞的电子散射过程,以及迁移、扩散和捕获等作用的电荷输运过程。通过对带电状态平衡模式的划分,研究了介质二次电子发射及带电状态的暂态变化、微观分布、稳态特性。研究结果表明:介质表面的带电过程可以根据介质表面电流的变化程度分为二次电子平衡模式、泄漏电流平衡模式及共同模式;二次电子平衡模式下样品呈现表面带电状态,而泄漏电流模式下呈现深层带电状态。泄漏电流平衡模式转向二次电子平衡模式过程中,稳态二次电子产额增加,表面负电位增强;总电荷量和平衡时间常数由于平衡模式的改变呈现相反的变化趋势。研究方法和结果有助于介质二次电子的机理研究和微放电效应的工程抑制技术。
In view of the complex influence of charged state of dielectric material on the secondary electron emission in the micro-discharge effect of space, the dynamic characteristics of the secondary electron of the dielectric material after electron irradiation are investigated for the first time from the perspective of the charge balance model by numerical simulation. The numerical simulation model combines the Monte Carlo method and the finite-difference time-domain method, taking into account the electron scattering process of elastic and inelastic collisions, and the charge transport processes such as migration, diffusion and capture. Through the division of the balanced mode of charged states, the transient changes, the microscopic distribution and the steady state properties of the secondary electron emission and charged state of the medium were studied. The results show that the charging process of the medium surface can be divided into the secondary electron balance mode, the leakage current balance mode and the common mode according to the change of the surface current of the medium. In the secondary electron balance mode, the sample presents the surface charged state, while in the leakage current mode Show deep charged state. Leakage current balance mode Steady secondary electron balance mode, the steady-state secondary electron yield increases, the surface negative potential increases; the total charge amount and equilibrium time constant due to the balance mode changes showed the opposite trend. The research methods and results are helpful to the mechanism research of medium secondary electrons and engineering inhibition technology of micro-discharge effect.