Central region of SKKUCY-9 compact cyclotron

Abstract

The development of a 9 MeV compact cyclotron for theproduction of radioisotopes for medical applications has been recentlycompleted. The machine accelerates negative hydrogen ions generated from aninternal PIG (Penning Ion Gauge) ion source following spiral orbits. Some ofthe structures designed for early beam acceleration, including a pair ofcenter poles providing ions a circular direction, the head of the ionsource, and the electrodes, are located in the center of the cyclotron. Inthis paper we discuss and evaluate the design of the central region thatpulls the ions from the chimney of the ion source and directs them into theequilibrium orbit. The magnetic field produced by the center poles wasanalyzed using the magnetic solver in OPERA-3D TOSCA, and the phase errorand ion equilibrium orbit, which is dependent on the kinetic energy withinthe designed field, were calculated using CYCLONE v8.4. The electric fieldproduced in the acceleration gap was designed using an electrostatic solver.Then, the single beam trajectory was calculated by our own Cyclotron BeamDynamics (CBD) code. The early orbits, vertical oscillation, acceptable RFphase and the energy gain during the early turns was evaluated. Final goalwas to design the central region by the iterative optimization process andverify it with 1 MeV beam experiment.