Positive-ion accelerator is a term used to describe a device that accelerates positively charged particles. Also known as ion accelerators, these devices function through various processes such as electrostatic acceleration, magnetic acceleration and resonant acceleration. Ion accelerators have numerous applications, including materials science, nuclear physics, and medical applications such as cancer therapy. Synonyms for positive-ion accelerators include ion guns, particle beam accelerators, charged particle accelerators, electrostatic accelerators, cyclotrons, and synchrotrons. These devices have contributed significantly to the advancement of modern technology and will continue to be essential in various scientific disciplines.