Lifetime and quantum efficiency advances in self-healing controlled porosity reservoir photocathodes

Electron beams for such applications as free electron lasers demand high brightness, picosecond-pulsed photoemissive electron sources. The controlled porosity reservoir (CPR) photocathode is a self-healing electron photoemitter. Its design is inspired by thermionic dispenser cathodes, offering extended lifetime of the easily-contaminated cesiated surface. We report atmospheric handling and subsequent self-healing and describe efforts underway to increase quantum efficiency (QE) well above the existing 0.1%-class ultraviolet performance of a Cs:W system by using other surface coatings.