New photo-injector sources having fast response time, long lifetime and relatively high-quantum efficiency (QE) are very needed for many applications. Metallic cathodes are promising candidates to supply high-intensity and good quality electron beams. We carried out measurements utilising thin films and a smooth bulk made of yttrium (Y). The Y thin films were produced by pulsed laser deposition (PLD, using a XeCl excimer laser) in high vacuum. It was covered, in situ, by a gold film to avoid oxidation. The Y smooth bulk was mechanically processed in air. The laser used to get experimental values of photoemission was a KrF excimer laser of 5 eV photon energy and 23 ns pulse duration. The maximum accelerating voltage applied to the photodiode (the anode) was+25 kV. The measurements of photocurrent were performed at different laser energies. We found that the output current was depended on the cathode surface. The higher QE values were obtained for the smooth cathode. It provided a maximum output current of 8.4 A, at 25 kV and 12 mJ laser energy. The maximum QE was 7.0x(10)^-5.
Photoelectron performance of Y thin films and Y smooth bulk cathodes
CARETTO, GIUSEPPE;MIGLIETTA, PAOLA;NASSISI, Vincenzo;PERRONE, Alessio;SICILIANO, MARIA VITTORIA
2008-01-01
Abstract
New photo-injector sources having fast response time, long lifetime and relatively high-quantum efficiency (QE) are very needed for many applications. Metallic cathodes are promising candidates to supply high-intensity and good quality electron beams. We carried out measurements utilising thin films and a smooth bulk made of yttrium (Y). The Y thin films were produced by pulsed laser deposition (PLD, using a XeCl excimer laser) in high vacuum. It was covered, in situ, by a gold film to avoid oxidation. The Y smooth bulk was mechanically processed in air. The laser used to get experimental values of photoemission was a KrF excimer laser of 5 eV photon energy and 23 ns pulse duration. The maximum accelerating voltage applied to the photodiode (the anode) was+25 kV. The measurements of photocurrent were performed at different laser energies. We found that the output current was depended on the cathode surface. The higher QE values were obtained for the smooth cathode. It provided a maximum output current of 8.4 A, at 25 kV and 12 mJ laser energy. The maximum QE was 7.0x(10)^-5.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
