Development of Electron-emitting Film for Spacecraft Charging Mitigation: Observation, Endurance and Simulations

Abstract

Prevention of spacecraft charging and discharge has become increasingly important as GEO satellites employ higher bus voltage. There are numerous mitigation techniques against spacecraft charging including electron emission from the spacecraft chassis. A new electron emission device operating in completely passive manner has been developed, which utilizes the field enhancement at the triple junction formed by metal and insulator exposed to space. It is named as Electron Emitting Film for Spacecraft Charging Mitigation (ELF's CHARM). Micro-etching was applied to polyimide-copper laminate film to manufacture a laboratory prototype. ELF utilizes prebreakdown electron emission current leading to arcing at the triple junction but maintains the current at the steady state. The electric field at the triple junction is macroscopically enhanced by charging of the polyimide film and microscopically by dielectric impurity on the copper surface. Theoretical rough estimate gives a current of 100 to 1,000� A. The laboratory experiment confirmed stable current emission from 10 to 100 � A from a sample of several cm 2 for 4 hours. Its robustness against ground handling and in-orbit contamination has been also demonstrated.