I recently got into eletronics, and there are some concepts I am having a hard time understanding. I was looking around youtube and saw this video of a small EMP generator, I understand the basics of it, the magnetic field inducts a current thus frying electronics, but what I'm interested in is why there is a spark gap in the schematics. What does it do ?
Presumably the high voltage converter is rectified and put through a multiplier, otherwise this circuit wouldn't work. The capacitors in the multiplier are charged up by the DC and when the voltage becomes high enough to jump the spark gap, all of the energy stored in the capacitor(s) is dumped into the coil, thus producing a powerful EMP. You can think of the setup as building up pressure until it reaches a certain point, and suddenly releases all of that pressure all at once. You can see how that would be much more powerful than simply passing the current through the coil.
The spark gap provides abrupt onset of energy movement; depending on how the spark/plasma extinguishes, you may also get abrupt ending of energy movement.
The abrupt changes in energy into the "coil" implement abrupt changes in magnetic fields.
Abrupt changes in magnetic fields are one form of EMP.