The voltage intensifier circuit works as follows..
the primary step up a pulse to the secondary coil... the pulse passes thru the diode and goes thru the two chokes to the water charging it. When the pulse terminates, the chokes reverse its voltage so across the diode and secondary (input) another positive pulse will come out, however there is a time with no voltage potential present to little negative . If the inductors are allowed to collapse to a higher voltage than the secondary the diode will conduct during pulse off too.. doubling the frequency
the frequency doubling can be seeing from the capacitor perspective too...
the higher the voltage the secondary collapse the higher the inductors will be allowed to collapse..and so on...so During the collapse the capacitor and inductor voltage initially subtracts from each other although not changing the polarity of the cell or current flow since a coil resist the change in current with a voltage... thereto the pulse doubling... the choke acts as a modulator...
Since there is moment where the cell plus coil become zero volts my impression is that we can keep adding charges to the water during this time... here is what meyer talks restricted current allow voltage to take over and do the work...