Central region of SKKUCY-9 compact cyclotron

Abstract

The development of a 9 MeV compact cyclotron for the production of radioisotopes for medical applications has been recently completed. The machine accelerates negative hydrogen ions generated from an internal PIG (Penning Ion Gauge) ion source following spiral orbits. Some of the structures designed for early beam acceleration, including a pair of center poles providing ions a circular direction, the head of the ion source, and the electrodes, are located in the center of the cyclotron. In this paper we discuss and evaluate the design of the central region that pulls the ions from the chimney of the ion source and directs them into the equilibrium orbit. The magnetic field produced by the center poles was analyzed using the magnetic solver in OPERA-3D TOSCA, and the phase error and ion equilibrium orbit, which is dependent on the kinetic energy within the designed field, were calculated using CYCLONE v8.4. The electric field produced in the acceleration gap was designed using an electrostatic solver. Then, the single beam trajectory was calculated by our own Cyclotron Beam Dynamics (CBD) code. The early orbits, vertical oscillation, acceptable RF phase and the energy gain during the early turns was evaluated. Final goal was to design the central region by the iterative optimization process and verify it with 1 MeV beam experiment.

Optimization of Ion Source Head Position in the Central Region of DECY-13 Cyclotron

“…Therefore, optimization of the initial electric and magnetic fields was performed to determine the starting position of the ions and the geometry and position of the puller that pulls the ions from the chimney of the ion source [1]. The optimization can be carried out by looking for a correct position of the ion source head relative to the puller before minimizing the problem with the acceleration process.…”

“…The first problem is caused by an insufficiently high vacuum, and a calculation that has already been done in the ARRONAX Cyclon 70 cyclotron shows that a vacuum level of 1 × 10 -6 Torr is needed if the targeted maximum beam loss is about 10 % [2]. The second problem comes from the vertical oscillation of ion beams hitting dee components and ion source arms; it can be overcome by adjustment of vertical gap of the center block [1]. The third problem comes from a radial oscillation that is caused by the insufficient accuracy of the gap between the head slit of the ion source and the puller.…”

Simulations of Beam Quality in a 13 MeV PET Cyclotron

“…Beam dynamics studies in cyclotrons were also conducted in Korea for a 9 MeV [3] and 13 MeV [4] PET cyclotrons, in China for a 10 MeV [5], a 14 MeV [6] and a 75-100 MeV [7] ones, and in Russia for a dedicated 2.5 MeV/A (A is atomic mass number) heavy ion cyclotron [8]. Except in references 1 and 6, the general results were presented without much detail as provided in this paper.…”