Metallic photocathodes prepared by pulsed laser ablation deposition for application to bright electron sources

Abstract

AbstractWe present the results of our investigation on metallic films as suitable photocathodes for the production of intense electron beams in radio frequency (RF) photoinjector guns. Pulsed laser ablation deposition (PLAD) technique was used for growing Mg and Y thin films onto Si and Cu substrates in high vacuum of 10−5 Pa and at room temperature. The morphology, the structure, the thickness and the contamination level of thin films surface deposited on Si were deduced by using different diagnostic techniques. Thin films deposited on Cu have been tested as photocathodes in an ultrahigh vacuum photodiode chamber at 10−7 Pa. Relatively high‐quantum efficiencies have been obtained for the deposited films, comparable to those of corresponding bulks. Samples could stay for several months in open air before being tested in a photodiode cell.The deposition process and the role of the gas absorption on the photocathode surface and its influence on the photoelectron performances are also presented and discussed. Copyright © 2010 John Wiley & Sons, Ltd.