A Monte carlo study on internal charging of onboard subsystem during the July 2004 energetic electron event
用蒙特卡罗方法计算2004年7月电子暴事件对星上分系统的内部充电效应

Internal dielectric charging (IDC) is a significant hazard to satellites which are exposed to the space radiation environment,especially to those passing through the Earth's radiation belts. As known,solar events,such as flares,CMEs,SPEs and electron storms,are the primary causes of satellite anomalies. In ground simulations of IDC effect,the Monte Carlo method is more sophisticated to deal with dielectrics of complicated geometry and the complexity of interactions between particles and materials. It should work better than some empirical equations which are usually involved. In this paper,we present a case study to evaluate IDC effect,utilizing GEANT toolkit which is based on the Monte Carlo method. The space event of July 2004 is taken as an example,and the energetic electron flux measured by GOES SEM is used as the particles environment data. To examine the impact of IDC on some structure rather than simplified planar dielectric,a generalized cubic onboard subsystem is constructed,with shields on each side and 10 Printed Circuit Boards (PCB) inside. The GEANT toolkit is utilized to simulate the interaction of injecting elections with the shields and PCBs' dielectric and the electron deposition. The maximum electron field strength inside these PCBs is calculated,which helps evaluate quantitatively the effect of IDC and its relation to energetic particles environment. In this case,a strong field in the dielectric is derived,which is enough to cause a 'potential hazard' of breakdown. This may be related to some intense anomalies of satellite in orbit during this storm event. Accordingly,the method introduced here can facilitate the vulnerability assessment in the shield design,and reduce the risk of operational satellite systems from IDC damage.