Need 1 amp, 24volt from a 25KVDC supply

[chuckey]

This all sounds very weird. So here is a weird solution. Make yourself a 25KV+ variable capacitor. Make sure that the frame is connected to earth via the winding of a step down transformer. Connect the shaft of the variable capacitor to a motor (don't ask where it gets its supply from). Now as the capacitor changes in value the charge on it plates will vary (Q = 1/2 C * V^2). As the charge changes it will cause a current flow through the primary of the transformer, the step down ratio will change this to a more usable current.
Connect up banks of LEDs in series on modular PCBs, get about 20KVs worth, stick a resistor in series to drop the final 5KV and to limit the current to a suitable value. facing each PCB use a solar cell to generate a voltage. Connect the solar cells in series/parallel to get your 24v @1A.
Frank :-o

 

[Zaphappy]

Well here is a switch that might do the trick (it's a modular switch)

http://hvswitch.com/

And yes I realize the linear approach is unrealistic yet not impossible. The switching regulator is most reasonable method unless I had a nice cool river near by
to dissipate the heat

- - - Updated - - -

Now I like this solution... I'll get right to work on it... I think a corona wind motor to drive the varicap ??? I actually thought about the solar cell method but with a gas/arc type light source... It might actually work but wow what a pain...

 

[dick_freebird]

Even -if- you could make a linear regulator stepping down
1000:1, the current is still limited and I bet you don't have
1A to burn, coming off the 25kV supply.

So you'd need a switching converter with a primary voltage
exceeding the 25kV, which is not too available.

Now this 25kV is coming from somewhere and maybe you
should think about stuff like putting an aux winding on the
flyback transformer that makes the HV, or maybe sharing
the HV line in frequency-domain, putting chokes on it
and inserting a ~ 30VAC HFsignal that you can pull off at
the other end and rectify / regulate. Kinda like power
over ethernet only backwards.