Van de Graaff generator is used for

A Van de Graaff generator is an electrostatic device designed to produce very high voltages, often reaching millions of volts [1]. This high-voltage potential creates a strong static electric field that is primarily used to accelerate charged particles, such as protons, ions, or electrons, to high speeds and energies [1]. Because only charged particles are influenced by electric fields (F=qE), they can be propelled toward a target for applications in nuclear physics research, material science, and medical sterilization [1]. While it generates a high voltage, it is characterized as a constant-current source with very low current output, making it unsuitable for generating large currents. It was one of the first types of particle accelerators, providing the stable and controllable beams necessary for early artificial nuclear disintegration experiments.

Sources

1. [1] https://en.wikipedia.org/wiki/Electrostatic_particle_accelerator