TDPerk wrote:Plasma has much lower mass, but can have much higher frequency, correct?
I dunno. I think you want a plasma physicist to know. Plasma confinement would seem to me to be limited by coulomb forces, and I would suppose the density can approach that of other states of matter, but you'd need to look at the densities different folks have generated. The crazy UFO story on the web about the TR-3B Alien Replication Vehicle is that the Mercury is pressurized to 250,000 atmospheres. I have no idea if that is possible, nor what density it would give, but certainly if you were going to toy with an Hg plasma design, you'd want to ask these questions. Let me note again,
I am not endorsing these kinds of stories as I find it very long odds there is any truth to them.
I don't see why you pass anything through the slip rings but DC.
The device needs to be driven by a 1w+2w AC signal, and perhaps pulsed AC as with Woodward's most recent patent app. The higher the frequency the better. One advantage to using plasma is you are no longer limited by the acoustic velocity of a solid, to work with whatever frequency for whatever thickness. So you want to use the highest frequency you can--millimeter wave would be a nice choice if you have those resources. If not you can put up with the crappy waveforms from a standing wave magnetron for a couple hundred bucks, and by using two of them, you can hope to get your 1w+2w and be able to control the phase between the components. Certainly though, you don't want to put all this power gear on the thrust measurement arm without a reason so you're likely better off passing AC than DC, Depends how much you can shrink the power system though. I can tell you even miniaturized, it appears the power system for a UHF MET will greatly outmass the thruster it powers (2-3 orders magnitude), so the power system mass is very important to consider. You would not put it on a balance arm unless forced by other concerns (like impedance matching requirements) to do so.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis