Emittance Compensation for an SRF Photo Injector

Many future electron accelerator projects such as energy recovery linacs (ERLs), high power free electron lasers (FELs) and also some of the new collider designs rely on the development of particle sources which provide them with high average beam currents at high repetition rates, while maintaining a low emittance. Superconducting radio frequency (SRF) photo injectors represent a promising concept to give just that, offering the option of a continuous wave (CW) operation with high bunch charges. Nevertheless, emittance compensation for these electron guns, with the goal of reaching the same level as normal conducting sources, is an ongoing challenge. This paper is going to discuss several approaches for the 3-1/2-cell SRF gun installed at the accelerator facility ELBE at the Helmholtz Center Dresden-Rossendorf including the installation of a superconducting solenoid within the injector’s cryostat and present the currently used method to determine the beam’s phase space.