Wanted to add this to the "Idea Bin".
I am working a little on this, but I will remain with AC to achieve resonance at the primary.
This circuit allows the secondary to charge the capacitor via pulse train, while the chokes provide equal voltage potential to prevent discharge through the water fuel cell.
So the choke winding should match the secondary winding to provide equal potential.
A large capacitor will take more Pulses to charge - IE pulse train.
Perhaps this will produce enough for a plasma discharge.
On the rest time of the pulse train the energy stored in the cap is discharged through the fuel cell.
As the chokes collapse - overshooting the potential and brings this energy back into the secondary, along with the pulse train again.
With my setup the capacitor needs to remain small to allow sufficient voltage to build up to penetrate the water.