Pelletron

Pelletron is a family of electrostatic particle accelerators that use a chain of metal pellets to carry electric charge from a high-voltage terminal to the accelerating structure inside a vacuum chamber. The Pelletron design, marketed by the National Electrostatics Corporation, is a variant of the Van de Graaff generator and is widely used for research in nuclear physics, materials science, and related fields. In a typical machine, a motor drives a continuous loop of small pellets that travel inside a vacuum tube between rollers. As the pellets pass the charging region near the high-voltage terminal, they gain charge from a charging system such as a corona electrode and then transport that charge along the loop to the rest of the accelerator.

Pelletrons are commonly configured as tandem accelerators, where ions are produced at ground potential, accelerated toward the high-voltage terminal, and then, after passing through a stripper stage near the terminal, experience additional acceleration as they move away from the terminal. This arrangement can yield ion energies in the multi-megaelectronvolt range, depending on terminal voltage and configuration. The pellet chain approach reduces mechanical wear and arcing compared with belt-driven systems and is well suited to achieving high terminal voltages in a compact form.

Applications of Pelletrons include ion beam analysis, materials modification, and fundamental nuclear physics experiments. They are used in university laboratories and national facilities, and are available in several sizes and configurations, including single-ended and tandem arrangements.