Are you serious about this? So, since the OP did not answer a single one of my questions, I'll ask you.Pulsing DC appears to be a possible route to increased electrolytic efficiency. If the OP wants to experiment in that murky area, let's help as we can.
Where do you see compelling evidence of this? The only solidly written paper out of the 4 you linked to drew the opposite conclusion.
How do we help him? Can you even push 250W into water using 12VDC pulses @ 50mHz? What would you need to do that? Pure water? use of a catalyst? Use of an electrolyte? Is the geometry, design or material of the electrodes significant? Is the pulse width/shape significant?
Even if we were all as convinced as you seem to be yourself, and wanted to help with this, how can we begin if we do not know even the tiniest bit of information about how to design this thing or what the working theory tells us about how it needs to operate?
This request is fundamentally different than the other requests we get on this board. We get... 1) questions from people about how to do things based on solid and well understood principles and we apply our knowledge of those principles to help ...and 2) questions regarding things we may not familiar with, but the poster has enough knowledge of the theory behind what they are doing to know where they need help and can give us a fairly precise idea of what they need, so that we can use our knowledge of scientific or technological practices to help them take the next step.
In this case, however, the poster has no working theory. They have asked us the help them design an illegal instrument and is either unwilling to explain why, or has absolutely no idea why this instrument needs these specifications.
The radio emissions for this thing, if it uses square waves, will be all the way from the fundamental (42mHz) all they way up to god knows what. If we wants true rectangular pulses, the harmonics will extend into the gHz. The fundamental is squarely in a range that is held by private and amateur mobile radio. The harmonics effect TV, FM, VHF, UHF.... Is he going to properly shield this thing? How? Or is he planning to get FCC permission to run it?
I could help with this. It actually covers a lot of ground I have considerable experience with, but unless my basic questions get answered, I couldn't, even if I wanted to. Instead I'm accused of 'jumping his ****' for asking them. What does that tell you?
BTW, I am closer to 60 than 50, so not entirely pink.