I suspected that's what the large bandwidth was intended for and why this might be thought of as complicated by a PHD. The impedance will change as you change frequency, and so your amplifier will experience a change in it's loading characteristics as you attempt to find the "Sweet spot."
I still don't see it as a deal killer. Impedance matching is mostly important to insure that power transfers efficiently. You can still transfer power with an impedance mismatch, you will just be dealing with losses. Again, as efficiency ought not to be of primary concern, I am thinking that a big enough heat sink would tolerate any mismatch. Another issue might be eliminating harmonics and parasitics. I'm thinking that if the leads between the drivers and the capacitor are kept short enough, this shouldn't be much of a problem at these low frequencies.
This is an issue all the EE's are not in complete agreement about. Certainly, if you are not continuously matched as you sweep, then you'll have different power into the thruster at different frequencies, and you'll have a very difficult time determining where the natural resonance and maximum thrust is.
I thought of that. It can be manually corrected by creating a look-up table for calibrating the impedance and drive so that it compensates for the changes as you vary the frequency, or someone could write a bit of code to create the compensation as a software component of the driver code.
In other words, modify your driver program to do impedance matching frequency correction on the fly. If the characteristics of the capacitor are predictable, then it should be easy enough to incorporate an equation in the driver software to modify the output waveform amplitude to compensate for the impedance changes.
Might take a bit of trial and error to make sure it's consistent across the entire rage of frequencies, but that's what tinkering is for!
Also, mismatching causes lots of rf flying around which is not good for your instrumentation. Since we planned to use a Mettler H20 and it is entirely mechanical, not so much trouble as could be, but. . .rf is rf. It gets everywhere.
The RF problem could be a SERIOUS problem. When you have 200 amp pulses at 1-2 mhz, you are going to HAVE Radiant RF, pretty much regardless of what you try to do to get rid of it. You can suppress it, but making it play nice with sensitive balances or other instrumentation might be a difficult problem.
I recall reading about the attempt by John Cramer's test of the Mach Principle with his "Mach Guitar
" and thinking to myself, I will be very shocked if that experiment actually works. The Drive levels were so high I thought the system couldn't help but suffer from some sort of feedback problem.
I looked for years for some word of his results, and finally I found where he said the results were inconclusive because the experiment seemed to be plagued with feedback problems.
One more thing, The system needs to be in mechanical but not electrical resonance. If it goes into electrical resonance you will easily exceed the 50 volt dialectric breakdown threshold. I see no reason why the system won't work with just the mechanical aspects of it resonant.
On the other hand, if it becomes mechanically resonant, the varying thickness of the dielectric may also cause the varying voltage on the plates to exceed the 50 volt threshold. This might require that it be driven at a lower amplitude than originally anticipated.