Superconducting RF Photocathode Gun for Low Emittance Polarized Electron Beams

The use of an RF electron gun with a magnetized cathode in place of a DC gun for ILC may eliminate the need for emittance damping rings. So far only DC guns have been used to provide polarized electron beams because of the very high vacuum level needed for survival of the Gallium Arsenide (GaAs) cathode material used to generate polarized electrons. Maintaining adequate lifetime of GaAs cathode material requires vacuum levels in the 10 torr range. While vacuum levels around the 10 torr range are common in a normal conducting RF gun, the cryogenic pumping of the cavity walls of a superconducting RF (SRF) gun may maintain vacuum in the range needed for GaAs cathode longevity. Advanced Energy Systems, Inc. is collaborating with Brookhaven National Laboratory to investigate the generation of polarized electron beams using a SRF photocathode gun. The team is developing an experiment to study the quantum lifetime of a GaAs cathode in a SRF cavity and investigate long term cavity performance while integrated with a cesiated GaAs cathode [1]. This paper reviews the design and analysis performed to develop a method to prepare and install GaAs cathodes into a SRF cavity in support of this experiment.