Investigations of surface charging effects due to interacting plasma plumes

Spacecraft accumulate surface charge due to incident plasma environments, both naturally-occurring and artificially-induced. Some common plasma sources that can induce surface charge include plumes of electric propulsion (EP) devices, the solar wind, or ionospheric plasmas. Resultant charging along exposed surface elements of a spacecraft can lead to electrical damage, such as electrostatic discharge. One relatively unexplored aspect of spacecraft charging concerns investigating the interaction between multiple plasma sources and their effect on spacecraft surface charging. Instabilities arising from these coupled plasma interactions may introduce anomalous charging phenomena that are not currently well defined.

We present a preliminary analysis of the effect that interactions between space plasmas of similar density profiles have on surface charging. In this work, we focus on the hypothetical scenario of two plasma plumes of comparable temperature and density of an ion thruster plume ejecting normal to the same surface. This is an investigative example that may be generalized towards plumes from multiple electric propulsion thrusters, or plumes due to plasmas created from micrometeoroid impacts. Utilizing particle-in-cell (PIC) simulations, each plasma phenomenon is simulated on a dielectric surface. First, we analyze the effect of a single plume on surface charging, then compare behavior to two interacting plasma plumes. We discuss the effect that this has on surface charging and their implications for spacecraft safety.