Final Technical Report

Lawrence Ives ; Eric Montgomery ; Zhigang Pan ; Blake Riddick ; Donald Feldman ; Lou Falce

关键词: photocathode;    RF electron gun;    accelerators;   

DOI  :  10.2172/1052145
RP-ID  :  Final Technical Report
PID  :  OSTI ID: 1052145

学科分类：核物理和高能物理

美国|英语

来源: SciTech Connect

【 摘 要 】

This program applied reservoir cathode technology to increase the lifetime of cesiated tungsten photocathodes. Cesiated tungsten photocathodes provide a quantum efficiency of approximately 0.08% when cesium is initially applied to the surface. During operation, however, the cesium evaporates from the surface, resulting in a gradual decrease in quantum efficiency. After 4-6 hours of operation, the efficiency drop to below useful levels, requiring recoating on the emission surface. This program developed a cathode geometry where cesium could be continuously diffused to the surface at a rate matching the evaporation rate. This results in constant current emission until the cesium in the reservoir is depleted. Measurements of the evaporation rate indicated that the reservoir should provide cesium for more than 30,000 hours of continuous operation. This is orders of magnitude longer operation then previously available. Experiments also demonstrated that the photocathode could be rejuvenated following contamination from a vacuum leak. Recoating of the emission surface demonstrated that the initial quantum efficiency could be recovered.