木星环绕探测任务中的内带电风险评估

Internal Charging Evaluation in Jupiter Exploration Mission

木星拥有类似地球辐射带的辐射带结构,其辐射带质子通量是地球的10倍,高能电子通量比地球高2~3个数量级,且最高能量可达1 Ge V。因此木星探测任务的抗辐射设计是任务成功的关键。选择3种不同倾角大椭圆探测轨道,仿真分析了2种介质在变化能谱下的内带电过程。仿真结果表明,对于环氧树脂(Fr4),由于电阻相对较小,电子通量较大的近木点的充电电荷,会在远离辐射带时泄放,其最大充电电场取决于近木点的电子通量;对于聚酰亚胺(Kapton),由于电阻相对较大,充电电荷不能及时泄放,不同轨道间电荷逐渐累计,最大电场不断增加。另外,环木轨道倾角越大,越有利于降低充电电场。和地球GEO轨道相比,不同电阻介质在环木轨道的充电差异相对地球GEO轨道较小。

Jupiter has a simi lar radiat ion belt structure as Ear th. The proton flux in Jupiter＊s magnetosphere is about 10 times of that in the Earth. The electron flux in Jupiter＊s magnetosphere is about 2~3 magnitude order higher than that of the Earth, and the maximum energy of electron is about 1 GeV. So, the anti-radiation design is one of the key technologies in Jupiter mission. Three elliptical orbits with different inclinations and two kinds of dielectric are selected, and the internal charging processes in time- varying electron environment axe simulated. For Fr4 material, the conductivity is relatively small and the deposited charge will leak off when the spacecraft is far away from the center of radiation belt. The maximum charging field is determined by the maximum electron flux. For Kapton material, the conductivity is relatively large and the deposited charge will be accumulated between different orbits, so the charging field will grow gradually. Large inclinations of orbit will benefit in decreasing charging field. Comparing the internal charging behavior of Jupiter elliptical orbit with that of GEO orbit, it is found that the difference of charging field between Fr4 and Kapton in Jupiter orbits is smaller than that in GEO orbit.