Two-Stage, Two-Gap, Light- and Heavy-Ion Cyclotron Study

A detailed study of a separated-magnet two-stage cyclotron has been made. For elements heavier than S, ions are preaccelerated by a 700 keV Cockroft-Walton and then injected into the first stage (lower gap) of the cyclotron. After acceleration, extraction and stripping (from charge Q to 4Q) they are returned to the center of the second stage (upper gap, whose center line is 15 inches above that of the lower gap) and further accelerated. For ions lighter than S, preacceleration takes place in a small cyclotron and the ions are injected directly into the second stage of the large cyclotron. Protons may be accelerated from 4 to 200 MeV, 3He from 12 to 630 MeV and U from 620 to 2130 MeV. The magnitude of external beams of heavy ions is limited by heating and sputtering of the electrostatic deflector extraction system. The turn separation for uranium ions at the final radius is 16 mm, so extraction efficiencies above 90% should be possible. At 90% it is estimated that 1 particle microampere of uranium ions will be obtained.