Advantages of the Superconducting 3½ Cell SRF Gun in Rossendorf

This paper describes the features of the 3½ cell SRF gun from Rossendorf and the advantages and challenges of superconductivity. One advanced working regime of the SRF photo injectors is to produce short pulses with high bunch charges and low transverse emittance running in cw-mode. The quality of this electron beam is crucially for future FEL's with very short wave lengths. The main challenge is to compensate the growing transverse and longitudinal emittance with increasing bunch charges. Therefore, some procedures for emittance compensation for the 3½ cell SRF gun will be discussed.