notice the quotes around "trigatron"- meaning it probably is just a made up word. Anyway basically I think he means your utilizing the Xenon flash as sort of a trigger, when you start dealing with high voltages-things tend do get a little unstable, and in this case spark. If you used a normal switch, every time you flipped it, it would make a spark just before the connection closes. This little spark would cause great wear and tare on the switch. Using the flash- its the gas Xenon that completes the gap and the spark wont hurt anything.
However seeing as how the tutorial is not very good anyway- this is just my guess as to what "trigatron" means. Hope that helped.
