New configuration of metallic photocathodes prepared by pulsed laser deposition

We propose a new photocathode configuration which presents the quantum efficiency and work function of yttrium (Y) and at the same time preserves all of the advantages of copper (Cu) when inserted into a radio-frequency gun. The configuration consists of a disk of Y covered by a coating of Cu deposited using the pulsed laser ablation technique, while masking the central part of the Y disk by a shield making the photoemission directly from the Y bulk possible. The new device was characterised by scanning electron microscopy to deduce the morphology and by X-ray diffraction to obtain structure information on both Cu film and Y substrate. The electrical resistivity of the Cu film was also measured obtaining a value slightly greater than that of bulk high purity Cu.