Deep dielectric charging characteristics of ring structure irradiated by energetic electrons

Abstract

Deep dielectric charging in ring structure irradiated by energetic electrons is one of the major factors causing spacecraft anomalies. In this paper, based on the physical processes of charge deposition, transport and accumulation, we establish a 2-D deep dielectric charging physical model of a ring structure consisting of insulating materials, electrodes and aluminum shield. Deep dielectric charging properties of insulating materials irradiated by electron energy spectra are simulated and analyzed under typical space environment and extreme space environment. Furthermore, the influences of aluminum shield, insulating material properties and thickness on deep dielectric charging are investigated. When the thickness of aluminum shield is larger than 3 mm, the maximum electron-beam density reduces to 10-10 A/m2, which is so low that it can not induce high electric field within materials. Selected polyimide (PI), polytetrafluoroethylene (PTFE) and composite epoxy resin (FR4) as electrical insulating materials, space charge transport, accumulation and electric field in insulating material of the ring structure are analyzed. It is indicated that the maximum electric field obeys the sequence as follows: PTFE> FR4> PI. Finally, it is found that the electric field is obviously enhanced with the increasing thickness of insulating material. This work paves the way towards the mitigation of deep dielectric charging.