A particle accellerator that uses a Van de Graaff generator to produce a high electrical potential, or voltage, at one end of a long cylinder. This very high voltage forms a powerful electric field along the length of the cylinder. Charged particles (electrons or ions) will "fall" or be accelerated from the high voltage end of the cylinder to the low voltage end (or vice versa if their charge is negative). The potential produced by the Van de Graaff generator can reach millions of volts, and the ions can be accelerated to energies of several million electronvolts (MeV).