Space charge effects, being one of the most significant collective effects, play an important role in high intensity cyclotrons. However, for cyclotrons with small turn separation, other existing effects are of equal importance. Interactions of radially neighboring bunches are also present, but their combined effects has not yet been investigated in any great detail. In this paper, a new particle in cell based self-consistent numerical simulation model is presented for the first time. The model covers neighboring bunch effects and is implemented in the three-dimensional object-oriented parallel code OPAL-cycl, a flavor of the OPAL framework. We discuss this model together with its implementation and validation. Simulation results are presented from the PSI 590 MeV Ring Cyclotron in the context of the ongoing high intensity upgrade program, which aims to provide a beam power of 1.8 MW (CW) at the target destination.

We describe a large scale simulation effort using Object Oriented Parallel Accelerator Library, that leads to a better quantitative understanding of the existing Paul Scherrer Institut high power proton cyclotron facility. The 1.3 MW of beam power on target poses stringent constraints on the controlled and uncontrolled beam losses. We present initial conditions for the Ring simulation, obtained from the new time-structure measurement and the many profile monitors of the 72 MeV transfer line. A trim coil model is developed, including trim coil TC15, which is needed to avoid the dangerous r ¼ 2 z resonance. By properly selecting the injection position and angle (eccentric injection), the flattop voltage, and phase, very good agreement between simulations and measurements at the radial probe RRE4 is obtained. We report on 3-4 orders of magnitude in dynamic range when comparing simulations with measurements. The relation between beam intensity, rms beam size, and accelerating voltage is studied and compared with measurement. The demonstrated capabilities are mandatory in the design and operation of the next generation high power proton drivers. In an outlook we discuss our future plans to include more physics into the model, which eventually leads to an even larger dynamic range in the simulation.

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