A frind of mine recently had fun testing a custom high energy PSU, too cool not to pass on:
"This photo was taken during routine testing of my 400 joule discharge PSU.
The PSU dumps 4,500V pulses to the load, at a rate of three 400j jolts per second.
The load resistor is a 10-ohm, 450-watt beastie which gets damn hot during testing - more than 200degC, despite the fan.
The load resistor consists of maybe 100 turns of resistance wire. The resistance wire is probably Monel or nichrome. One turn is only insulated from the next by an oxide coating on the wire. At each pulse, there's about 45 volts between adjacent turns. Once the resistor gets hot enough, the insulation starts breaking down. Spectacularly...
I'm glad I had the camera handy!"
Dave.