Modulating Potential Energy

sanman

Electric charge is an example of a form of energy whose energy potential we can readily and conveniently manipulate, to modulate its state, to make it go up and down cyclically.

What is the most dense form of energy whose energy potential we can quickly manipulate or modulate?

I'm talking about being able to create wide swings in the state of potential energy of a system, to make it go up and down cyclically, with the widest possible amplitude.

Antiphon

Charge is not a form of energy.

The densest is nuclear energy which can be manipulated and modulated quite well in a nuclear reactor.

sanman

Okay, charge potential is a form of energy then.

How can the energy state within the nucleus be manipulated and modulated? I've heard of Nuclear Magnetic Resonance doing this, but how would a nuclear reactor do this?