Robust, Long Life Photocathodes

Development is in progress on free electron lasers, synchrotron radiation light sources, and other advanced particle beam devices. A key component of the electron gun is a high efficiency photocathode. A serious issue is cathode lifetime, which is often a few hours. There is a need for advanced photocathodes that are efficient, robust, and capable of long life. The proposed program will utilize recent advances in reservoir cathode technology to develop photocathodes where the work function reducing material on the emission surface can be replenished within the device. This will dramatically extend the lifetime while maintaining high quantum efficiency. The proposed program will design and test cathodes to verify performance.Commercial Applications and Other Benefits: Next generation light sources, such as free electron lasers, produce bright, coherent electromagnetic radiation. Light sources producing THz, IR, visible, near UV, deep UV and soft and hard x-ray radiation are becoming critical for materials science, medical research, and defense applications. Synchronization and electron beam brightness requirements often dictate use of a photoinjector. The dispenser photocathodes developed in this program will be applicable to such systems and will provide a new alternative for long-lived, efficient photocathodes for both green and UV drive laser systems