A particle accelerator is a device used to accelerate particles to high speeds. The two crossword solutions for the term particle accelerator are ION (3 letters) and BETATRON (8 letters). An ION is an atom or molecule that has gained or lost one or more electrons, giving it a net electric charge. A betatron is an electromechanical device used to accelerate electrons to high energies. It works by using an alternating electric field to accelerate electrons in a vacuum tube.