Have light gases like hydrogen or helium been explored for ion propulsion? asks what it asks. In the body of the question it's restated as:
Has the "ion sorcery" for light gases like hydrogen and helium been explored experimentally for future ion propulsion technology? What about neon at least?
There was some heavy pushback on the question's premise based on a very narrow view of how electric propulsion is used. The Dawn mission was power-limited rather than mass-limited, so in order to get there quickly they went with a high mass species; xenon. Xenon has an additional advantage that it's easier to ionize so lower mass and lower power consumption components can be used to produce the plasma.
But what I (think that I) see there is a concerted effort to prevent the asking of my question in a way that doesn't presuppose all possible uses of electric propulsion in the future will be Dawn-like in nature.
It takes a while to read through everything there, but of course the answer to my question is "Yes" and since nobody was willing to address the question as asked I've posted a new answer.
Now down voting on that one has begun as well.
Why all the negativity and down voting here? Is someone working on a low-mass species thruster in some startup and doesn't want others to get the idea that there might be some mission-space for a very high Isp thruster or one that could harvest hydrogen/helium and reuse it?
Question: What's going on with all the downvoting on my answers here?