This device was originally described in 1924 by E. Marx and probably it is the easiest way to produce single pulses of very high voltage. This device is currently used to test the dielectrical resistence of industrial machines...or produce very actractive sparks and lightnings.
The Marx generator is composed by capacitors charged in parallel trought high value resistences, and discharged in series by firing spark gaps. When the high voltage is applied to the generator, the capacitors (Cx) charge trought the charging resistors (Rx); when totally charged, the first gap fires for the voltage (or it is triggered by an external system) and so, this put two capacitors in series which overvoltage the nex gap and so forth. When all the capacitors are in series, the output voltage is about the input voltage for the number of capacitors ( Vout » Vin * Ncaps). The first charging resistor is very important because it protects the capacitors from overloads. Like for the rechargable batteries, there are two ways to charge a Marx generator quickly: constant current source or constant voltage source; using constant voltage, the charge is too fast, but the charging resistors dissipate as much energy as stored in the capacitors, while using constant current this loss is considerably reduced.