Chinese Acad Sci, Inst High Energy Phys, Beijing 100080, Peoples R China
Low emittance and high intensity electron beams are needed for the high gain, short wavelength FELs. To meet the requirements of the proposed DUV FEL facility in Shanghai, we designed a 1.5-cell, S-band photocathode RF gun using the emittance compensation techniques. Based on the simulation codes of POISSON, SUPERFISH and PARMELA, this design aims at producing a beam of epsilon (n,rms) = 2.3 pi .mm.mrad, Q = 2 nC/bunch, E(k) = 4.8 MeV at the gun exit with the field gradient of 100MV/m on the cathode. In this paper, we present the design considerations and the simulation results.