Cathode Performance during Two Beam Operation of the High Current High Polarization Electron Gun for eRHIC

Two electron beams from two activated bulk GaAs photocathodes were successfully combined during the recent beam test of the High Current High Polarization Electron gun for eRHIC. The beam test took place at Stangenes Industries in Palo Alto, CA, where the cathodes were placed in radially opposite locations inside the high voltage shroud. No significant cross talking between the cathodes were found for the pertinent vacuum and low average current operation, which is very promising towards combining multiple beams for higher average current. This paper describes the cathode preparation, transport and cathode performance in the gun for the combining test, including the QE and lifetimes of the photocathodes at various steps of the experiment.
Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA