Audio OT, but it is High Voltage SS

Ok,

I need to create a variable constant power source (V*I). The voltage needs to be about 1000V and the current from 0 to 20mA. My thoughts are a flyback transformer circuit with a PWM that is closed loop on a V*I feedback. Any thoughts on real circuits?

Thanks,

Dale

P.S. This will create a controlled arc between two closely spaced tungsten electrodes (melting fiber)