High-Fidelity Simulations of Fixed-Field Alternating Gradient Accelerators

The next-generation particle accelerator for nuclear physics research likely will involve high-energy electron-ion collisions. A promising candidate for the cost-efficient acceleration of high-charge electron bunches is the non-scaling fixed-field alternating gradient (FFAG) synchrotron. Existing numerical codes include only some of the key effects required for the accurate design and evaluation of non-scaling FFAG accelerators. Therefore, this project will augment an existing code for tracking the acceleration of charged particles. The existing code already includes special features required to handle large rectangular dipole magnets without a well-defined synchronous trajectory. Additions to this code will include generalized magnetic fringe-field models and the self-fields of the electrons. Phase I developed a simple, three-dimensional fringe-field model for rectangular magnets that have a horizontal gradient in the dipole field. An optimal approach for adding space-charge effects was identified, and a simple two-dimensional model was implemented. The enhanced code was used to simulate an existing accelerator design. Phase II will extend the simple 3D magnet model to more general magnets, including curved magnets. A fully-parallel 3D space-charge model will be implemented and the tracking operations will be parallelized. The resulting code will be used for detailed parameter scans of possible designs for non-scaling FFAGs, and will include misalignment effects, magnet mispowerings, multipole errors, fringe fields, and space-charge. Commercial Applications and Other Benefits as described by the awardee: The software should directly benefit scientists working to design high-current electron accelerators required for fundamental advances in experimental nuclear physics.