Design and Numerical Assessment of a Passive Electron Emitter for Spacecraft Charging Alleviation

In this paper, we examine the theoretical basis for using passive unheated electron field emitters to control hazardous levels of spacecraft charging. We present the experimental evidence related to the capabilities of passive and low-power active field emitters. The concept of passive field emitters is detailed looking at their characteristics and location on a model satellite typical of a commercial geostationary satellite. The assessment is performed by means of numerical simulations. The generation and extraction of electrons is simulated at micrometric scale. Their flow is modeled at spacecraft scale to assess spacecraft absolute and differential charging alleviation. The system shows good promise limiting the inverted voltage gradient situations, observed especially on solar panels where cover glasses are more positive than solar cells. This situation is known as very risky in flight, possibly leading to sustained secondary arcing powered by the photovoltaic solar arrays themselves. Finally, we review how existing design practice would be modified by the presence of such passive emitters.