Simulation of Short-Range Wakefields in Accelerating Structures for X-Ray Sources

The DOE has a large investment in accelerator-based light sources for scientific discovery. For these systems, the short-range wake fields, which are generated by electron bunches traveling through the cavities, are of critical importance. These short-range wake fields are a significant component of the power lost by the electrons being accelerated or stored in the ring, and they also can lead to intra-bunch head-tail effects that degrade beam quality. Thus, for cavity design, these short-range wake fields must be computed with each design iteration, in order to evaluate their effects. This project will develop new computational tools, based on the well-established particle-in-cell technique, to simulate these wake fields accurately and efficiently. Several independent features a (moving window to reduce the simulation domain and hence the computational effort, conformal boundary algorithms for accurate representation of curved cavity shapes, and perfect dispersion algorithms to reduce numerical errors) will be combined to efficiently run accurate simulations of short-range wake fields. The new code features will be benchmarked for comparison to test cases with known results. Commercial Applications and other Benefits as described by the awardee The robust tool for the computation of short-range wake fields would be made available to DOE-funded researchers under appropriate commercial and non-commercial licenses, enabling the U.S. to maintain a leadership position in cavity design, as well as in high-performance electromagnetic computations. Enhanced capabilities and reduced costs for accelerator-based light sources should facilitate discoveries in many areas of medicine, science, and national security