Schematic of the Van de Graaff accelerator

Secondary windings connected in series feed the high-voltage terminal. The system provides a beam only during the negative half cycle, with a voltage variation between zero and the peak value the machine was designed to deliver. Sulfur hexafluoride gas is used for electrical insulation.  

Low-frequency transformers with iron cores connected to rectifier circuits can generate potentials up to approximately 1 MV. Traditionally, iron core transformers are insulated by oil, but the recent models use sulfur hexafluoride. The energy rating of these generators is in the range from 0.3 and 1 MeV with beam powers up to 100 

ICT machines produced recently have energy ratings from 0.3 to 3.0 MeV and beam power capabilities up to 100 kW. Nearly 180 of these machines, the majority of them rated for less than 1 MeV, have been installed as of the early 1990s. They are used mainly for cross-linking of heat-shrinkable film, plastic tubing, and electric wire.  

---