Editing Van de Graaff generator (section)

== Use as a particle accelerator ==
[[File:Tandem Accelerator Diagram.jpg|thumb|500px|A simplified diagram of a Tandem Accelerator]]
The initial motivation for the development of the Van de Graaff generator was as a source of high voltage to accelerate particles for nuclear physics experiments.<ref name="Van de Graaff" /> The high potential difference between the surface of the terminal and ground results in a corresponding [[electric field]].  When an [[ion source]] is placed near the surface of the sphere (typically within the sphere itself) the field will accelerate charged particles of the appropriate sign away from the sphere.  By insulating the generator with pressurized gas, the breakdown voltage can be raised, increasing the maximum energy of accelerated particles.{{r|hinterberger}}

=== Tandem accelerators ===
[[File:Nuclear accelerator in NCSR Demokritos.jpg|thumb|Van de Graaff Tandem accelerator at [[National Centre of Scientific Research "Demokritos"|NCSRD]] in Greece]]
Particle-beam Van de Graaff accelerators are often used in a "[[tandem accelerator|tandem]]" configuration with the high potential terminal located at the center of the machine. Negatively charged ions are injected at one end, where they are accelerated by attractive force toward the terminal. When the particles reach the terminal, they are stripped of some electrons to make them positively charged, and are subsequently accelerated by repulsive forces away from the terminal. This configuration results in two accelerations for the cost of one Van de Graaff generator and has the added advantage of leaving the ion source instrumentation accessible near ground potential.{{r|hinterberger}}

=== Pelletron ===
{{main|Pelletron}}
The pelletron is a style of tandem accelerator designed to overcome some of the disadvantages of using a belt to transfer charge to the high voltage terminal.  In the pelletron, the belt is replaced with "pellets", metal spheres joined by insulating links into a chain.  This chain of spheres serves the same function as the belt in a traditional Van de Graff accelerator – to convey charge to the high voltage terminal.  The separate charged spheres and higher durability of the chain mean that higher voltages can be achieved at the high voltage terminal, and charge can be conveyed to the terminal more quickly.{{r|hinterberger}}