Introducing GunLab – A Compact Test Facility for SRF Photoinjectors

Superconducting radio-frequency photoelectron injectors (SRF photoinjectors) are promising electron sources for high brightness accelerators with high average current and short pulse duration like FELs and ERLs. For the upcoming ERL project bERLinPro we want to test and commission different SRF photoinjectors, optimize the beam performance and examine photocathode materials in an independent test facility. Therefore we designed GunLab to characterize beam parameters from the SRF photoinjectors in a compact diagnostics beamline. The main challenge of GunLab is to characterize the full six dimensional phase space as a function of drive laser and RF parameters. Here we present design and estimated performance of GunLab. Motivation bERLinPro [1, 2] will be an ERL demonstrator which combines high average beam current with small emittance which is determined by the electron injector. In a step-bystep approach the photoinjector concepts will be developed and commissioned towards the final bERLinPro-gun. In the last two years Gun 0.1 [3] and Gun 0.2 [4] comprising of hybrid Nb/Pb SRF gun cavities were tested successfully. Both tests were done at HoBiCaT [5] extended by a test beamline. Based on the gained experiences we designed GunLab as an independent and optimized beamline to characterize the next SRF guns for bERLinPro and to investigate different phase space measurement systems for the extracted electron bunches. With GunLab the complete six dimensional phase space of electron bunches in the energy range of up to 3:5 MeV can be investigated. The realization of GunLab is one of the important milestones of the bERLinPro project on the way to optimize the performance of SRF photoelectron