The driver is based on an UC3844 current-mode controller. It runs the transformer in flyback mode. The driver output feeds into a beefy IGBT, an IXGN200N60. The IGBT has a snubber network and a bunch of shunt resistors measure the emitter current. 

There's also a big decoupling cap to smooth things out.

The driver was tuned to about 25kHz (ideally it would be a tad lower, around 21kHz) and the gate drive looks quite decent. 

The nice thing about the driver is that the power output can be set with a simple trimpot.