Van de Graaff generator
Other electrostatic machines like the Wimshurst machine or Bonetti machine work similarly to the Van De Graaff; charge is transported by moving plates, disks, or cylinders to a high voltage electrode. For these generators, however, corona discharge from exposed metal parts at high potentials and poorer insulation result in smaller voltages. In an electrostatic generator, the rate of charge transported (current) to the high-voltage electrode is very small. After the machine is started, the voltage on the terminal electrode increases until the leakage current from the electrode equals the rate of charge transport. Therefore, leakage from the terminal determines the maximum voltage attainable. In the Van de Graaff generator, the belt allows the transport of charge into the interior of a large hollow spherical electrode. This is the ideal shape to minimize leakage and corona discharge, so the Van de Graaff generator can produce the greatest voltage. This is why the Van de Graaff design has been used for all electrostatic particle accelerators. In general, the larger the diameter and the smoother the sphere is, the higher the voltage that can be achieved.
Electrostatic generator
In 1878, the British inventor James Wimshurst started his studies about electrostatic generators, improving the Holtz machine, in a powerful version with multiple disks. The classical Wimshurst machine, that became the most popular form of influence machine, was reported to the scientific community by 1883, although previous machines with very similar structures were previously described by Holtz and Musaeus. In 1885, one of the largest-ever Wimshurst machines was built in England (it is now at the Chicago Museum of Science and Industry). The Wimshurst machine is a considerably simple machine; it works, as all influence machines, with electrostatic induction of charges, which means that it uses even the slightest existing charge to create and accumulate more charges, and repeats this process for as long as the machine is in action. Wimshurst machines are composed of: two insulated disks attached to pulleys of opposite rotation, the disks have small conductive (usually metal) plates on their outward-facing sides; two double-ended brushes that serve as charge stabilizers and are also the place where induction happens, creating the new charges to be collected; two pairs of collecting combs, which are, as the name implies, the collectors of electrical charge produced by the machine; two Leyden Jars, the capacitors of the machine; a pair of electrodes, for the transfer of charges once they have been sufficiently accumulated. The simple structure and components of the Wimshurst Machine make it a common choice for a homemade electrostatic experiment or demonstration, these characteristics were factors that contributed to its popularity, as previously mentioned.