In answer to your question #2. Yes a DPF can produce a high energy/temperature ions, but it does so by fusing them. At least some or most of them, that’s where a substantial fraction of their velocity comes from. I’m not certain why fusing them is undesirable?
Question #3 on scaling: Can’t scale the machine. Can’t make it bigger or smaller. At least not from what we know NOW. No reason you couldn’t operate several of them together though. There is a little bit of tweeking you can do to mess with the ion beam vs X ray emissions. All the energy the DPF releases is released in the form of either x-rays or ion beam. Higher voltage increases the fraction emitted as x-rays, which for an ion propulsion system (which I assume you’re aiming at) is undesirable.
