Van de Graaff Generator Simulation

A Van de Graaff generator builds up millions of volts with a rubber belt. A comb at the bottom sprays charge onto the moving belt, the belt carries it up into a hollow metal dome, and a comb inside hands it over. Because charge on a conductor always moves to its outer surface, the inside of the dome stays field-free and can always accept more charge.

This Van de Graaff simulation shows the belt, the combs and the charge spreading over the dome, and plots the voltage as it climbs. The voltage stops rising when leakage through humid air balances the belt, when a spark jumps to a nearby earthed sphere, or when the surface field reaches the breakdown strength of air.