A friction generator is the glass drum Nairne type, invented yonks before the Van de graaff. [thats the correct spelling Al] The other type of friction generator is the single plate Cuthbertson type. Both a darned sight more reliable than a Van de graaff! seen pictured here.
Sorry going off topic here.
Van de Graaff, bit gready on the A' there, generator is friction from the belt, if memory serves. As a device the VdG is quite spectacular, if it is a big one, as its dome can support great discharges. Ours was ex Bristol University and came with Prof Davy - yes that family of Davy. Sadly, a brilliant mind, but a poor teacher, unless you were interested. I have no doubt the same effect would be had using the others with that dome, though. So is the Wimshurst friction also? - double back to read previous info. What in effect is going on is depletion of electrons from one area to another. Mount a variated plate without the friction and you get some induction, towards a dynamo ultimately, but fundamentally a different process.
The arcing produces X rays amongst other emissions and in early experiments scientist overdosed themselves on X ray to the extent that there were more incidence of radiation related health issues with this technology than with the early nuclear industry. Or put another way, the nuclear industry learned from the errors made with experimenting with high voltage discharges. There is a picture of a guy sat inside a Faraday cage in a industrial unit sized VdG with discharges going all ways.
What I do not know is how useful this all is. For instance I know that electricity travels more efficiently at high voltage, see the National Grid. However for use and safety we knock 20,000 volts back to 240 volts, here - other countries different, but in the same area. The currant is better and it does not arc. But is a Wimshurst attached to a windmill in clear air stepped down to 240 volts at the house going to be better than a 24 volt truck alternator stepped up to 240 volts to run you private green world? I ask this with the advice that 240 volt generators to go on a stick cost a lot of money.
