There were two large generators in the lower basement of ENS that powered the tokamak fusion research center. I say that they were there because last year, they were removed. I don't think anything was put in their place.

Each one was roughly the size of a suburban. They were half embedded in the concrete floor, which was on some sort of special shock mount. They had all sorts of crazy air conditioning hooked up to them to cool them. They were originally the types of generators that electric utilities use. In fact, one of them powered Tyler, Texas in the 1930's. However, they had been extensively modified.

In normal generators some large power source turns the rotor, which generates electrical power (usually in the form of three phase alternating current). These worked on a different system. The rotors were slowly spun up to a very large rotational speed over the course of a few days. They accumulated not only the momentum from their mass, but also from a "magnetic mass." When they were set to discharge, they would go from a few thousand RPM to zero in a few degrees of rotation (almost instantly). The resulting amount of energy was not only enough to fuse atoms, but also enough to shake the entire building.

for the curious, they are said to behave like an ideal current source of very large magnitude when discharged. The buss bars leaving these things were superconducting.