Avalanche Injected Photocathode

One of the key developments in the present generation of FEL's is the RF photocathode injector enabling production of electron bunches with nC of charge at emittances of several mm-mrads. Advances in photo-injector design have produced significant improvement in operational capability of FEL sources. A major issue in electron accelerator and FEL communities is the search for a suitable photocathode source. In this proposal we discuss a new concept for an active photocathode device that can deliver ~106 electrons per photocarrier. This new concept is based on employing a photon triggered controlled avalanche injected photocathode, employing robust III-V nitride materials. The proposed project if successful will open up new prospects for FEL photo injector sources, enabling new performance levels to be attained. New more robust higher output current photocathode technology is needed to further advance the technology. RF photocathode injectors have been an enabling technology for FEL's and are responsible for the significant advances in linac design over the past decade. The photocathode concept presented in this proposal promises to lay the foundation for a new multiple wavelength family of robust high reliability, high brightness photocathodes with high current output that could significantly impact future FEL's.