In-Orbit Demonstration of Newly Developed Passive Electron-Emitting Film for Spacecraft-Charging Mitigation

Recently, a passive electron-emitting film has been developed for the purpose of neutralization of all types of spacecraft charging. Applications are inclusive of satellites with high bus voltage in geostationary Earth orbit. This passive-type component emits electrons continuously from its triple junction under an inverted potential gradient condition after being exposed to a geostationary Earth orbit substorm. In this paper, the verification test has been conducted after designing circuitry that measures the surface potential as well as the emission of the film. In the ground test, the emitter was biased to a high negative potential with respect to the vacuum chamber to simulate the spacecraft potential achieved while floating in space plasma. The substorm condition and the satellite charging are simulated by irradiating the emitter with an electron beam. Under these conditions, the performance of the emitter has been confirmed via the developed circuitry. These results allow the flight demonstration of the electron emitter and circuitry as a mission payload on Horyu-2, the first satellite developed and deployed by the Kyushu Institute of Technology.