As with all of Tesla's works, the Peace Ray was very simple in plans and very difficult, or impossible in application.
Our current understanding of reality, brought to us by Newton and Michelson-Morley will never produce a working Peace Ray. It would have to be by pure accident. Like accidentally tuning an AM radio to an FM station.
The stories of the Peace Ray that i do not feel are accurate is that they took the ray to an army base, where Tesla disintegrated a car and a mountain top and then all the Generals said this is too powerful, so we won't use it. I haven't seen any war type people ever turn down a more powerful weapon.
As soon as we throw out all our shtupid science and start actually dealing with the real world, it will become very clear and apparent what Tesla saw. Once you know the structure of the universe, it is quite easy to take apart.
And thus, we will not see this kind of knowledge until we no longer have war.