A particle nuclear accelerator that derives its name from the two stages of acceleration that particles undergo.

In one version, heavy negatively charged ions are accelerated through one potential difference before being stripped of more electrons and accelerated again in a system using two or more Van de Graaff generators.

Developed by U.S. physicist Robert J. Van de Graaff, 1901-1967; a Van de Graaff generator is an electrostatic generator in which high voltages are produced by a moving belt of insulating material that collects electric charges by induction and discharges them inside a large spherical electrode; used for accelerating electrons, protons, and other nuclear particles.