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介质深层充放电现象是诱发航天器异常故障的重要因素之一.分析了高能电子辐射下介质内部电荷沉积、能量沉积特性和电导特性,考虑了真空与介质界面电荷对电场分布的影响,建立了介质二维深层充电的物理模型,并基于有限元方法实现了数值计算.计算了高能电子辐射下聚四氟乙烯的深层充电特性.结果表明:真空环境下,介质的表面存在较弱的反向电场,随着介质深度增大,电场减小至零,随后逐渐增大,最大值出现在靠近接地附近,但在接地点,电场存在小幅降低.分析了不同辐射时间下(1 h,1 d,10 d和30 d),介质内部最大电位和最大电场的时空演变特性.随着辐射时间的增加,最大电位由-128V增加至-7.9×104V,最大电场由2.83×105V·m-1增加至1.76×108V·m-1.讨论了入射电子束流密度对最大电场的影响,典型空间电子环境(1×10-10A·m-2)下,电子辐照10 d时,介质内部最大电场为2.95×106V·m-1.而恶劣空间电子环境(2×10-8A·m-2)下,电子辐射42 h,介质内部最大电场即达到108V·m-1,超过材料击穿阈值(约为108V·m-1),极易发生放电现象.该物理模型和数值方法可以作为航天器复杂部件多维电场仿真的研究基础.
The deep charge and discharge phenomenon of the medium is one of the important factors that induce the abnormal failure of the spacecraft.The charge deposition, energy deposition and conductivity characteristics of the medium under high-energy electron radiation are analyzed, the influence of the interface charge of the vacuum and the medium on the electric field distribution is considered, The physical model of two-dimensional deep charging of the medium is established and the numerical calculation is carried out based on the finite element method. The deep charging characteristics of polytetrafluoroethylene under high-energy electron radiation are calculated. The results show that under the vacuum environment, the surface of the medium has weak reversal In the electric field, the electric field decreases to zero as the depth of the medium increases, and then increases gradually, and the maximum value appears near the ground, but the electric field decreases slightly at the grounding point.The electric field is analyzed under different irradiation time (1 h, 1 d , 10 d and 30 d), the maximum electric potential and the maximum electric field in the medium were observed.With the increase of irradiation time, the maximum potential increased from -128V to -7.9 × 104V and the maximum electric field increased from 2.83 × 105V · m-1 To 1.76 × 108V · m-1. The influence of incident electron beam current density on the maximum electric field was discussed. Under the typical space electron environment (1 × 10-10A · m-2), the maximum electric field Is 2.95 × 106 V · m-1. In harsh space electron environment (2 × 10-8A · m-2), the maximum electric field inside the medium reached 108V · m-1 after 42 h of electron irradiation and exceeded the material breakdown threshold · M-1), which is prone to discharge.The physics model and numerical method can be used as the basis for multi-dimensional electric field simulation of complex parts of spacecraft.