It seems to be implying that they ran a very high current through a small object for a very brief period of time as part of work to simulate nuclear weapon testing.
Completely uneducated guess here but wouldn’t this just be done with REALLY big capacitors.
So they’re charging up a gazillion capactors, then shorting them out, all at the same time, across a tuna-fish can. This produces tremendous currents, in the can, stresses it, and causes it to implode at huge velocities.
The device sucks up large amounts of energy. It’ll never be a power source unless they hit pressures high enough to cause a fusion reaction; and that’s not going to happen.
IIRC, there was a thread on this device a few months ago after AP? described it as high velocity rifle, capable of shooting “slugs” at 20 kilometers per second. The Atlas machine does reach very high current densities, and it does make things move very fast, but it is neither a source of power, nor a gun.