Measurements of Photocathode Operational Lifetime at Beam Currents up to 10 mA using an Improved DC High Voltage GaAs Photogun.

Grames, J. ; Poelker, M. ; Adderley, P. ; Brittian, J. ; Clark, J.

Technical Information Center Oak Ridge Tennessee

关键词: Photocathodes;    Beam currents;    Lifetime;    Vaccum systems;    Measurement;   

RP-ID  :  DE2007917249

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

This work extends past research at Jefferson Lab aimed at better appreciating the mechanisms that limit photocathode operational lifetime at high current (> 1 mA). Specifically, the performance of an improved 100 kV DC high voltage load locked photogun will be described. Although difficult to measure directly, we believe the new gun has better vacuum conditions compared to the original gun, as indicated by enhanced photocathode lifetimes exceeding 2000 C using a 1.55 mm diameter drive laser spot at the photocathode. In addition, the dependence of the lifetime on the laser spot size at the photocathode was measured and a charge density lifetime exceeding 10(caret)6 C/cm(caret)2 was measured with a 0.32 mm laser spot diameter.