Ion source and the internal beam currents of the CS-15 compact cyclotron

The Sloan-Kettering Institute CS-15 compact cyclotron was the first prototype built by the Cyclotron Corporation in 1967. The ion source is a cold cathode PIG type radially fitted into the 4-inch magnet gap. The ion source is simple, small, and capable of delivering large currents, but causes certain problems. For example, the beam current showed large fluctuations from time to time, resulting in unpredictable cyclotron performance. The ion source was operated with limited configurations, and beam current could only be adjusted by changing rf dee voltage. It was discovered that the power density of the arc column plays an extremely important role in determining ion source performance. (auth)