摘要
嫦娥三号实现'软着陆'中关键技术之一是精确把握关机高度.伽玛关机敏感器采用发射器向月面发射光子,通过接收器记录的光子数判断航天器与月面距离.利用Geant4对简化的发射器-接收器系统进行仿真,论证锥角发射器优势并证实工况非锥角发射器选用的决定性因素.通过发射器锥角微分分析充分说明伽玛关机敏感器选用120°锥角发射器的必要性和合理性,证实伽玛测距中光子散射分布特性与传统激光测距直线传播镜面反射不同,并展示二者显著差异.在仿真结果基础上并保证完成着陆任务前提下,对样机设计提出改善方案以减少放射性对航天器件的辐射损伤.
The key technology in ＂soft landing＂ for Chang＇e 3 is to accurately control the height between shutdown sensor and the lunar surface. gamma shutdown sensor uses a launcher to launch photons to the lunar surface and judges the distance between craft and the moon through the number of received photons. The software of Geant4 is used to simulate the simplified system of the launcher-acceptor. The simulation results show the advantages of the launcher with a certain cone launching angle when the craft is landing to the moon. And we find that the relative position of launcher and acceptor is not decisive factor of selecting the launcher with cone launching angle. By the detailed analysis of the scattering probabilities of the photons from the launcher to the acceptor at different scattering angles, we can get the reason that why we chose the 120° cone launching angle in the mission. The simulation data indicate that the most important scattering areas of the gamma launcher are quite different from the laser method. This work provides a way to optimize the structure of the gamma shutdown sensor to accomplish the mission and reduce the radiation dose.
出处
《中国科学：技术科学》
EI
CSCD
北大核心
2016年第6期643-648,共6页
Scientia Sinica(Technologica)
