Development of high stability resonant kicker for swiss free electron laser

A high stability resonant beam deflector system is being developed as part of the beam switching of the X-ray Free Electron Laser (SwissFEL) at Paul Scherrer Institute. To increase facility efficiency the main linac will operate with two electron bunches in one RF pulse. Three identical resonant kickers followed by a DC septum should separate the two bunches, that are 28 ns apart, and send them to two separate undulator lines. Shot-to-shot amplitude stability of each kicker should be better than +/- 82.5 ppm peak-to-peak, assuming the stability budget is equally split between phase and amplitude jitter. Development of the resonant kicker prototype and the precision measurement system is described. Preliminary measurements are presented.