Proton source

A proton/neutron source incorporating a cyclotron, in particular a superconducting cyclotron comprising a cylindrical superconducting magnet incorporating superconducting magnetic coils associated with pole pieces (12 to 14). A stream of ionised particles such as H particles, is continuously injected into the centre of the cyclotron beam space and is accelerated outwards in a spiral path under the combined effect of the magnetic field from the superconducting magnet, and RF energisation applied to sector-shaped electrodes (32-34). When the particles reach the required energy, they are removed from the spiral path by septa electrodes (1,2), and are passed across a proton storage ring (3) in a path of rapidly increasing radius under the influence of the falling magnetic field of the superconducting magnets. A certain distance out from the centre of the cyclotron, the magnetic field reverses, and the particles turn anticlockwise and enter a bending magnet (7) in which the route of the particles is bent back towards the cyclotron so that they eventually enter the proton storage ring (3). As they enter the ring, the particles are stripped of their electrons so that they become positively charged protons, which latter will circulate continuously round the storage ring (3) until required. Extraction from the ring may, for example, be by means of septa electrodes (75, 76).