A 20 kV DC tank supply

```I would like to built a 20 kV DC supply for my big coil. These are the
tentative specs:

- 20 kV DC output
- primary capacitor 0.1 uF, charged at 20kV --> 20 Joules
- maximum DC deviation: 1%
- maximum BPS: 800 Hz

If I use a 3-phase 14 kV pole pig and 6 diodes I get a ripple of 50*6 = 300
Hz. Voltage varies between 14 kV * 1.41 = 19.8 kV and
14 kV * 1.41 * 0.866 = 17.1 kV.

I need a flywheel capacitor to provide, roughly, enough energy for 3
primary capacitor chargings (at BPS = 800 Hz, I get almost 3 bangs between
each ripple top), that is 20 * 3 = 60 Joules allowing the top voltage to
drop down only 1%. That is:

maximum voltage drop = 20kV * 0.01 = 200V

Cflywheel = dQ/dV = 3 * Cprimary * 20kV/200 = 30 uF.

And this without taking care of losses!

I have still to protect the flywheel capacitor from discharging when the
rotary gap conducts: what about using a current limiting inductor for
feeding primarty capacitor and rotary gap?

Has anybody got some good idea or hints how to build such a DC power
supply?

Help!

P.S. Another solution would be to go with a stabilized 17,1 kV, but how to
"cut away" the ripple?

```