THE bERLinPro SRF PHOTOINJECTOR SYSTEM-FROM FIRST RF COMMISSIONING TO FIRST

Helmholtz-Zentrum Berlin (HZB) is currently constructing a high average current superconducting (SC) ERL as a prototype to demonstrate low normalized beam emittance of 1 mm·mrad at 100 mA and short pulses of about 2 ps. To attain the required beam properties, an SRF based photoinjector system was developed and during the past year underwent RF commissioning and was setup within a dedicated diagnostics beamline called Gunlab to analyze beam dynamics of both, a Copper cathode and a CsK2Sb cathode as well as their quantum efficiency at UV and green light respectively. The medium power prototype a first stage towards the final high power 100 mA design presented here features a 1.4×λ/2 cell SRF cavity with a normal-conducting, high quantum efficiency Cs2KSb cathode, implementing a modified HZDR-style cathode insert. This injector potentially allows for 6 mA beam current and up to 3.5 MeV kinetic energy, limited by the modified twin TTF-III fundamental power couplers. In this contribution, the first RF commissioning results of the photo-injector module will be presented including dark current analysis as well as measured beam properties with an initially installed Copper cathode.