Abstract: There is considerable interest in using RF photocathode guns and injectors in a variety of applications for electron sources. Unfortunately, the short operating time of the cathode and the complicated laser needed to drive the cathode limits these devices to the research laboratory. However, recent developments in cathode research indicate the possibility of a robust, long-lived cathode with high sensitivity at visible wavelengths. The combination of coating with a protective layer and operating at an elevated temperature could significantly increase the lifetime of cesium-antimony cathodes. This paper reviews the cathode quantum efficiencies and lifetimes observed in RF guns, discusses the drive laser issues and describes recent advances in both metal and cesium-based cathodes. !12
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