Effects of Wakefields on the Microbunching Instabilities at PAL-XFEL

High bunch compression in two bunch compressors is required to achieve a peak beam current of about 3.5 kA in PAL-XFEL. We investigated effects of longitudinal space charge wake and geometrical linac wake on microbunching instability for the PAL-XFEL in the design stage. We show that significant energy modulation can be generated by the space charge wake and can enhance the coherent synchrotron radiation microbunching in the compressors for the PAL-XFEL. In this paper, we evaluated the total gain of the microbunching in the 3.7 GeV PAL-XFEL accelerator system. The evaluation was obtained by performing analytical calculations of integral equation for coherent synchrotron radiation microbunching [1].