Cavity BPM design for PKU-FEL injector

A cavity beam position monitor (BPM) is designed for the injector of PKU-FEL Facility. The designed frequency of the dipole mode TM110 is 1.3 GHz, which is equal to the frequency of the main accelerator in PKU-FEL Facility. The cross-talk problem is solved by introducing two rectangular recesses into the cavity. The position resolution of the cavity BPM is about 10 mm, the dynamic range is more than 30 mm and the time response is bunch to bunch, which are sufficient for the PKU-FEL injector. Compared with the bunch power, the power dissipation of the main resonant modes excited by e-bunches can be neglected.