Electron Structures: How Does the ISS Ground Itself?

The International Space Station is floating through space so the thoughtful people in United States of America thought it just had to be up to code. That means that the ISS has to be properly grounded and can't be 'floating' with respect to surrounding plasma.

On Earth the resistivity of soil may be 7662 ohm -cm, in places, according to the United States' Department of Defence MIL-HDBK-419A. In orbit around the Earth the ion -  electron plasma makes the concept of grounding far different. The fine folks at NASA will seek to minimize hazards by making the space station's net charge the same as the surrounding plasma in space. If the space station has too large a potential difference between the chassis of the space station and the surrounding plasma an arc hazard develops. Nobody wants lightning hitting the ISS. Talk about hot carrier injection!

So, it has come to my attention that the USA and perhaps another nation or two has developed two ways of controlling the potential difference between the chassis of the ISS and the surrounding plasma. The first mechanical-electrical structure to control charge is a spike. The other is a noble 'gas' ion gun. I use the word gas carefully because there is nothing about this element that is gaseous as it is used on the ISS after it has been fired.

The spike has been considered since the brushes of the Van der Graaf generator were invented. Photocopiers have bristles on them to control charge. These bristles or spikes sweep or conduct and launch or conduct electrons in a very particular way. I want to focus on the spike on this post rather than the brushes though they have similarities. Mechanically, the spike looks like the beginning of a conductor. It seems to just terminate in space. Electrons surely travel the length of the conductor at a high rate of speed and then just launch themselves off the proverbial plank.They might accelerate into the dielectric after a relatively consistent velocity in the lattice of the conducting spike. Off the electron flies but what is the probability that it will just fly back to the conductor that launched it? The answer is very low. So the spike sheds negative charge making the chassis more positive providing half of the grounding for an orbiting structure.

Now I'm just making educated estimates at how all of this works but we have a century of research and experimentation to draw on postulate.

The ion cannon is fun speculation. When the crew or sensors of our International Space Station feel they are in electron deficit they fire an ion cannon (particle accelerator) of Xe ions into space. The trick is that moments before the Xe+ are accelerated they had a full complement of electrons. The electrons spread through the mechanical structure of the conductive apparatus into the hull of the space station chassis with a net addition of negative charge to the ISS superstructure.

My post today involves much speculation. The speculation into the grounding of such a complicated electrical system helps resolve problems on Earth such as the grounding of a regenerative braking subway train. Of course there are far more people that ride on subways when compared to a space station so far away in orbit.