Dependence of Solar Cell ESD Voltage Threshold on Cover Glass Secondary Emission Properties

Spacecraft interacts with the charged particles of the space environment, leading to their electrostatic charging. This charging depends on the surface materials and their exposure to space. Thus, it is different for different parts of the spacecraft. This differential charging is particularly important on solar panels, which are composed of various polarized elements juxtaposed over small distances. This leads to strong electric fields ultimately leading to electrostatic discharges (ESDs), themselves being the onset of destructive secondary arcs. Hence, controlling the onset of ESDs is a key factor to prevent damages on spacecraft. Two ways are generally envisioned to act on the ESD onset: the geometry of the solar cells and the material electrostatic properties. In this article, the control of the ESD onset is tackled through the study of the effects of the cover glass secondary emission properties on the voltage threshold of solar cell ESDs. This study is conducted numerically with the spacecraft plasma interaction software (SPIS)-ESD software, as the natural variability of physical samples and the impossibility to have materials with controlled characteristics render the experimental study unpractical, if even feasible.