Can you replace the dome with a capacitor? VdGG.

[nsled]

Just looking at all the homemade Van de Graaf generators, is there a reason you cannot just replace the big dome with a suitable capacitor? Sure seems a lot easier, is there examples of it?

[MRMILSTAR]

I've never built a VDG but I've built Tesla coils. I can think of several problems. The top load serves two purposes. First, it acts as a capacitor. Second, it acts as a discharge terminal. Since VDGs can generate several hundred thousand volts and more, the capacitor must be able to accommodate this voltage. A commercial capacitor with this voltage rating would be very expensive and large. The discharge terminal must be smooth with the largest practical radius to prevent the charge from leaking into the air as corona. This is why a sphere is ideal.

[nsled]

The "purpose" of a VGG aside, and knowing there are much better ways of charging a capacitor. What would happen? Let's say you put a 10kV capacitor wired directly to the outputs I'm guessing it'd charge up to reach an equilibrium between voltage and coronal losses well before it fails.

I just feel like this would be something well tried, yet I cannot find examples of it.

[haversin]

Having a top dome that surrounds the upper pully and collector is the key to a VDG achieving very high voltages because of the Friday Ice Pail effect. Once charge is placed inside the dome it can  transfer completely to the dome no matter what voltage the dome is. Without the dome, if one lead of a capacitor is connected to the upper collector and the other lead is connected to ground. The capacitor would only charge up to the voltage of the charge to ground.