There are much more high-voltage high-current mosfet's available
I guess it's a question whether the body diode is fabricated in all mosfets (rated for high or low voltage), and whether it allows current to flow backward up into the positive power supply (the 'rogue' current).
In addition I often see unexpected behavior in the mosfet model in Falstad's simulator.
you say that in order for a Nakagome charge pump to charge it has to be connected to the load
Just in the sense that a current path has to be available to include the capacitor in a loop in order to observe discharging as well as charging. I suppose you referred to a previous thread:
www.edaboard.com/showthread.php?267438-nakagome-charge-pump-doubt
The concept does work to accumulate charges on multiple capacitors.
Falstad's contains a spark gap element. This simulation demonstrates 4 capacitors, analog switches and 200V supply. The spark gap is set (perhaps unrealistically) to break down at 980V.
After a discharge the capacitors may take an extra cycle or two to charge, until voltage is high enough to span the spark gap.
The screenshot was taken as a discharge was occurring across the spark gap.
The diodes make life easier. They prevent current backflow.
The 50 ohm resistors are unnecessary. Without them each transition results in severe current spikes.
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Here is the link which contains the above simulation.
tinyurl.com/y32lfkry
By a click it:
1) Opens the website:
falstad.com/circuit
2) Loads my schematic in the simulator.
3) Runs it on your computer.
Your computer needs to have Java installed.