Invited Paper-Ion Injection from External Sources

Discussion is restricted to low and medium energy cyclotrons. Some reasons for using external injection are given. At the present time injection is either in the median plane or axial. Among the possibilities for injection in the median plane are cycloidal motion along a sector edge, linear motion by electrostatic compensation, and high energy injection with trapping into cyclotron orbits by change of charge. In the axial direction all methods have much in common--focussing down a hole in the magnet pole and inflection into a cyclotron orbit. As an example of the problems and possibilities with external injection the axial method is discussed in more detail. Topics include basic principles, beam quality, variable energy arrangements, bunching and the choice of injection energy.