> On the other hand, if you constantly keep pumping charge to maintain the desired potential difference between your original plates/grids, that precisely means

> On the other hand, if you constantly keep pumping charge to maintain the desired potential difference between your original plates/grids, that precisely means that you are not allowing your plates to be fully screened: you get your drive field back in between the plates, but now you're basically back to the unscreened case and it seems that my original objections hold. What happened to your previous realization that > Oh! I hadn't understood that the ion is what's being screened, but of course it would be. ? As I already explained: pumping electrons between the plates will (partially) restore unscreened conditions around them, but as the ion leaves, it goes into the surrounding plasma and gets screened, i.e. decoupled from the device, thus invalidating your original objections. As an aside, I find it odd that you decided to post this comment above the earlier subthread where I explained screening to you. Maybe you just don't know any better, but it creates an impression that you are trying to rewrite the history of this discussion.