Beam Stabilization by Using BPM in KU-FEL

Abstract

A Mid-Infrared Free Electron Laser (MIR-FEL) facility has been constructed for developing energy materials in Institute of Advanced Energy (IAE), Kyoto University. Since high brightness electron beams are crucial for the FELs, stabilization of the electron beam (beam energy, beam current, bunch spacing and beam trajectory) is very important for a stable FEL operation. For these reasons, the electron beam position which includes the electron beam energy information should be monitored precisely to realize the highly stable electron beam. We have been developing a feedforward and a feedback system using 4-pickup electrode type Beam Position Monitor (BPM) in Kyoto University FEL (KU-FEL) to generate a stable FEL light. A basic design of the BPM readout system has been completed and we have installed BPMs with accuracy of 10 μm for non-destructive measurement in the KU-FEL linear accelerator. BPM signals were observed successfully and a phase stabilized electron beam has been generated by a feedforward system. A feedback system using BPM to stabilize the beam position is under development.