RF Experience from 6 Years of ELBE SRF-Gun II Operation

At the electron accelerator for beams with high bril-liance and low emittance (ELBE), the second version of a superconducting radio-frequency (SRF) pho-toinjector was brought into operation in 2014. After a period of commissioning, a gradual transfer to routine operation took place in 2017 and 2018, so that now more than 3400h of user beam have already been gen-erated since 2019. During this time, a total of 20 cath-odes (2 Cu, 12 Mg, 6 Cs2Te) were used, but no serious cavity degradation was observed. In this paper, we summarize the operational experience of the last 6 years of SRF gun operation, with special emphasis on main RF properties of the gun cavity.