DC-SC photocathode injector for high average power FEL

To obtain high average current electron beams for high average power Free Electron Laser (FEL), a DC-SC photocathode injector is designed. It consists of DC extraction gap, 1+1/2 superconducting cavity and coaxial input system. High quality electron beams of CW mode or high duty factor can be obtained. The optimization of the injector and simulation of beam dynamics have been done. Model cavity experiments showed the correctness of the simulation.