I am trying to figure out how to determine the proper capacitor selection for a voltage multiplier circuit. I want to choose a capacitor which will give me the smallest voltage drop and ripple frequency.

Can anyone tell me what factors are to be taken into account when choosing capacitors for a half wave multiplier circuit?

The AC transformer kicks out 1200V at 35kHz, and 5mA.

Also, if the multiplier circuit is used to charge a capacitor how do you determine the RC time constant of the load capacitor?

 

First a reminder - high voltages at high frequencies are dangerous, even with the limited current. It is very unsafe to be working with high voltages without some experience to help guide you.

It takes time to push charge onto a capacitor. At 35 KHz, that's only 29 usec for the charging time, and only part of that time will the voltage be enough to actually do the charging. Your caps may have to be in the picofarad range, and you are really more likely to have the line of caps and diodes arcing over.