A cyclic particle accelerator in which charged particles fed into the centre of the device are accelerated in an outward spiral path inside two hollow D-shaped conductors placed to form a split circle. A magnetic field is applied at right-angles to the plane of the dees and an alternating potential difference is applied between them. The frequency of the alternating p.d. is arranged so that the particles are accelerated each time they reach the evacuated gap between the dees. The magnetic field makes them follow curved paths. After several thousand revolutions inside the dees the particles reach the perimeter of the dees, where a deflecting field directs them onto the target. In this device protons can achieve an energy of 10−12 J (10 MeV). The first working cyclotron was produced in 1931 by the US physicist Ernest Orlando Lawrence (1901–58). See also synchrocyclotron.
https://www.youtube.com/user/nsclmedia The US National Superconducting Cyclotron Society’s YouTube channel