Design of a novel bimodal cavity

Here, we introduce and analyze a novel concept of using one single cavity to support dual modes instead of using separate cavities. One advantage of using a dual-mode cavity is that only one cavity needs to be manufactured, which is space-saving and obviously economic. Apart from this, by operating both the fundamental mode and the certain harmonic mode simultaneously in one single cavity, bunch lengthening during the acceleration process could be linearly achieved, providing great potential in improving the beam brightness in linacs, storage rings, and other accelerating structures. Through the detailed design study, a structure combining the fundamental and the chosen second harmonic modes is characterized. The RF performance of the designed bimodal cavity is deeply analyzed, and it could be put into actual use for different goals to improve either the beam dynamic characteristics or the compactness of the certain system.