Several alternatives are available to make a HV DC supply.
It is certainly possible to series a pair and get 40 kV (AC) from a 200V supply.
Another approach would be to make a half wave voltage doubler with a pair of capacitors and diodes, using a single transformer.
If the low voltage side was designed to work at 100V, you'll need an appropriate transformer to turn the 220V mains to 110V. Or, you can run a bunch of lightbulbs in series to drop the voltage.
Created on Friday, May 25, 2001 12:35 PM EDT by James Lux