Cavity beam position monitor based on two off-axis resonant cavities by comparison method

A new concept for monitoring electron beam position based on two off-axis cavities is proposed, main performances of the beam position monitor are discussed using its main parameters, such as normalized shunt impedence. Two off-axis cavities excited dipole mode TM110 by off-center beam provides microwave signals strong enough for the detection of beam position, which can be measured directly by the ratio of the dipole mode amplitude from two cavities. The change of dipole mode amplitude reflects the beam displacement. RF front-end circuits are simplified by the method without phase detection and the common mode is heavily suppressed. Eigenmode characteristics as well as mode coupling coefficient between two cavities are studied by MAFIA and HFSS simulations, which prove the function of the