Efficient hybrid approach to the electromagnetic design of resonant cavities for side-coupled linacs

A novel hybrid analytical/numerical approach, implemented via homemade code, is exploited to design the microwave cavities of a linear accelerator (linac) characterised by a very complex geometry. A finite element method-based three-dimensional investigation is integrated with a multi-objective particle swarm optimisation technique in order to automatically design and optimise the geometry of the linac cavities. The cavity optimisation takes into account the typical figures of merit of a linac design. The hybrid approach is used to design a 27 MeV 3 GHz standing-wave side-coupled linac tank of 35 cavities including the end cells. The promising simulated results suggest that a global search approach is a useful and flexible tool for the electromagnetic design of accelerator cavities as well as other complex resonating multicavity structures.