木星磁场对航天器表面充电的影响分析
Effect of Jovian Magnetic Field on Charging of Solar-Array-Panel for Spacecraft: A Simulation Study
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摘要: 木星具有太阳系行星中最强的磁场, 而磁场会通过磁限制作用以及叠加动生电场对航天器表面充电情况造成影响。本文以木星高充电区域之极轨为研究对象, 采用SPIS软件模拟研究了木星磁场对航天器表面充电危险性的影响。研究结果表明:低轨区域由于二次电子在磁场中的回旋半径很小, 二次电子发射会受到抑制作用, 造成充电更加恶劣, 但是差分电势变化并不显著, 而高轨道区域则由于回旋半径很大, 未对充电情况造成明显影响, 此时由于势垒的存在造成了太阳电池帆板充电的缓和;动生电场的存在, 则会造成导体材料充电更加恶劣, 其充电电位的变化除导体自由电荷移动所产生的动生电势外, 还包括材料收集电荷移动所产生的额外电势, 因此模拟仿真结果与理论计算值差别较大, 此外动生电场还造成了太阳电池帆板上电势梯度的增加, 增加了相邻电池贴片缝隙的放电风险。Abstract: The interaction of Jovian planetary magnetic field, the strongest in the Solar System, and charging of solar-panels on spacecraft round Jupiter was mathematically modeled and numerically simulated with SPIS software.The influence of Jovian polar orbit on the charging behavior, including the secondary electron emission, charging potential and motional electromotive force, was investigated.The simulated results show that the negative impact of magnetic field in low orbits far outweighs that in high orbits.For example, in low orbits, the stronger magnetic field significantly worsens the charging properties because of the decreases of electron gyro-radius and secondary electron emission; in high orbits, the less strong magnetic field mildly affects the charging characteristics because electron gyro-radius is bigger and because the potential barrier enhances secondary electron emission.Moreover, the motional electromotive force (stronger than the calculated one) hurts the charging behavior and increases discharge-damage risk.