Systematic Cathode Study-Activation of a Thermionic Cathode, and Measuring Cesium Evaporation from a Dispenser Photocathode

摘要

The Free Electron Laser (FEL) is one of the Navy's 'future weapons' undergoing research and testing for implementation on naval vessels. The Naval Postgraduate School is joining in the Navy's Free Electron Laser effort by constructing a scaled-down version of the naval system-the NPS FEL. Our first research goal is to better understand the current thermionic cathode used in the NPS FEL system, the Eimac Y-845. This thesis will explore the outgassing of these cathodes as well as chart heater filament voltage vs. temperature, an important factor for understanding the operational regime the cathode will be in (primarily photoemission, or thermionic, or both). Additionally, we aim to examine a new type of Cesium Reservoir Dispenser Photocathode currently being built by the University of Maryland. Dispenser photocathodes are a promising technology in that they may have much longer lifetimes than other types of high quantum efficiency photocathodes. The concern with this new style of cathode relates to cesium release into the photoinjector cavity. We aim to ascertain the rates of cesium emission that users may encounter when utilizing these cathodes. low enough cesium emission for in-gun testing and use.