I put a bar over the top of the VdGG with spikes at each end pointing in opposite directions. It span very quickly. The spikes have such a strong electric field that they are able to ionise the air molecules and then repel them, creating a flow of ions or "electric wind" that you can feel with your hand. By Newton's Third Law, if the air is pushed one way then the spike must be pushed the other way. The two spikes produce a couple that is able to get the bar moving.
