I've just been talking to someone who designs switching supplies for HV. The standard technique is to use a whole bunch of secondary windings, each at a 500V to 1kV. These feed a bunch of rectifiers (usually full wave doublers), the outputs of which are then hooked in series.
This is different than using one giant winding for the secondary. The number of diodes, etc. will be the same either way, but you get better regulation and performance.
Created on Saturday, March 17, 2001 1:58 PM EDT by James Lux