• E.-S. Kim
  PAL, Pohang, Kyungbuk

We have quantitatively investigated effects of wakefields that are important for the controlling of short bunch length and small emittnace in X-ray FEL. We present the effects of coherent synchrotron radiation, linac geometrical wake in S-band and X-band linacs, space charge wake, resistive wall wake and roughness wake on the emittance and energy spread in the PAL-XFEL. The analytical results on the effects of the wakefields are also compared with the numerical simulation ones.

• E.-S. Kim, Y.J. Han, J.Y. Huang, S.J. Park
  PAL, Pohang, Kyungbuk

Longitudinal space charge wake is an important source that can generate microbunching instability at accelerator systems for X-ray free-electron laser. We present investigation to minimize gain of energy modulation due to the longitudinal space charge wakes that are caused at RF photocathode gun, two bunch compressors and linac at the PAL-XFEL, which include optimization of parameters for two bunch compressors and consideration of a laser heater. These studies are performd by using integral equation and numerical simulation methods. Design studies of a system for the laser heater are presented. We also show simulation results on effects of interaction between electron beam and laser.