It is a nuclear device or equipment.. it is a huge apparatus in nuclear reactors. In this particles like alpha, beta, neutron, proton are accelerated to very high speeds and then used to bombard atoms (nucleus) of heavy elements.
The cyclotron accelerates a charged particle in a magnetic field perpendicular to its speed. There are two chambers with a short distance between them. They have magnetic field in parallel directions. Particle enters with a speed in to one chamber. It moves in a semicircular path and then leaves the first chamber and enters the second chamber. Then here the particle is accelerated again in a semicircular path.
An alternating current is used to provide the magnetic field. Each semicircle the particle completes, the direction of magnetic field changes. So the particle goes in circular path to reach the speed required. it could be in kilometers/sec. or more.