Photocathodes: the state of the art and some news

The present cesium telluride cathodes have the capability to provide, for months, trains of picosecond pulses carrying a charge equal/higher than 10 nanocoulomb, for a total charge higher than the microcoulomb. However, they are very delicate. A possible way to increase their robustness is by covering them with a protective film of nanostructured carbon. Ferroelectric ceramics, as possible new robust photocathodes, showed an interesting level of emission with 532 nm–25 ps laser pulses.