CHALLENGES IN SIMULATING MW BEAMS IN CYCLOTRONS

The 1.3 MW of beam power delivered by the PSI 590 MeV Ring Cyclotron together with stringent requirements regarding the controlled and uncontrolled beam losses poses great challenges with respect to predictive simulations. We describe a large scale simulation effort, which leads to a better quantitative understanding of the existing PSI high power proton cyclotron facility. Initial conditions for the PSI Ring simulations are obtained from a new time structure measurements and 18 profile monitors available in the 72 MeV injection line. The radial beam profile measurement which is just located in front of the extraction septum is compared with simulations. We show that OPAL (Object Oriented Parallel Accelerator Library) can precise predict the radial beam pattern at extraction with a large dynamic range of 4 orders of magnitude. A large turn separation and a narrow beam size at the Ring extraction is obtained by adjusting parameters such as the injection position and angle, the flattop phase and the trim coils. A large turn separation and a narrow beam size are the key elements for reducing the beam losses to acceptable levels. The described simulation capabilities are mandatory in the design and operation of the next generation high power proton drivers.