High intensity problems in cyclotrons

Cyclotrons have so far produced currents up to the order of 200 micro-amps, this limit mainly be given by extraction losses and the brightness of the ion source. Future cyclotrons will operate with average currents in the milli-ampere region. To achieve these intensities injection from an external ion source into a ring cyclotron is the most promising route. For conventional extraction, without stripping, single turn extraction is necessary in order to keep losses and thus activation levels within tolerable limits. Longitudinal space charge forces tend to spoil the turn separation. They can be partially compensated with a high accelerating voltage and a flattopping higher harmonic. At beam power levels reaching 1 MW the problem of beam loading puts stringent tolerances on the RF-system. Additional problems arise with cooling of the targets as well as with space charge forces in the beam transport lines and in the cyclotron