A Decade of Progress in Cyclotrons -- Frequency-Modulated and Isochronous

The advent of the isochronous cyclotron, capable of accelerating a wide selection of particles with energies variable up to limits previously inaccessible, has spurred the development of techniques leading to increased knowledge of orbit behavior and hence to external beams of greatly bettered quality. Among these activities are improved methods of magnet design, of field control and of beam diagnostics, novel means of launching the projectiles and more effective extraction schemes. Increased versatility has engendered new obstacles; e.g., space charge and charge exchange problems in the use of heavy ions. Advances in synchrocyclotrons, though still largely in the planning stage, reflect the present state of the art of spiral orbit machines. Increased current is the major goal. A variety of schemes for better axial focusing and higher repetition rate are under consideration. Beam stretching and improved focusing by grids or by einzel-type lenses have already been achieved.