Optimization of a bunch compression at the ARC section of KEK-ERL test facility

Energy Recovery Linac (ERL) gets a lot of attention as a next generation period light source instrument for producing a high brightness and short pulse synchrotron lights. To achieve high quality beam with low emittance and short bunch length it is important to reduce an emittance growth due to Coherent Synchrotron Radiation (CSR) generated at dipole magnets. The beam optics and lattice design of the first scheme in KEK-ERL test facility, which is based on the previous design parameters, is optimized to suppress the emittance growth. The emittance growth rate is influenced by the matching between the transverse ellipse phase space and CSR kick direction as well as the spike in the bunch head appearing at the bunch compression, which causes strong CSR. In this paper, the effects were validated and optimize the beam optics and lattice design of KEK-ERL test facility. (author)