I am looking to make my own flyback transformer that can put out a DC voltage from 0 to -40 kV DC and a power of 400 watts, as most commercial flybacks do not go up to the specified power and typically do not provide a negative voltage. Thus, I was curious how I could build such a device and the what the required specifications for the components used in the transformer (i.e. the size of Litz wire and the amount of wraps on either side) would be to build a proper transformer.
Preferably, the voltage input for such a design should be 0-24 V DC with a transformer output that correlates with the input (basically resulting in an adjustable output based on an adjusted input if possible). The ripple of the -40 kV DC output should not exceed 350 V.
If the use of a single flyback transformer would be impractical for such power, how could I create an assembly of transformers that would collectively provide the needed power and voltage? Thank you.