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Persistent URL http://purl.org/net/epubs/work/39596257
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Record Id 39596257
Title Metal Photocathodes Preparation for Compact Linear Accelerator at Daresbury Laboratory
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Abstract The photoinjector of the CLARA FEL test facility Front End at Daresbury Laboratory is based on a S-band 10 Hz photocathode RF-gun operating with a copper photocath-ode which is driven by the third harmonic of a Ti:Sapphire laser (266 nm). The main aim of this study was to establish a procedure to prepare the Cu surface prior to installation so a Quantum Efficiency (QE) of 10-5 or higher can be achieved at laser power density below the ablation threshold of copper. The best results have been obtained by ex-situ chemical cleaning. This removed the surface oxide layer whilst at the same time producing a surface buffer layer. This inhibited the regrowth of native oxide for up to a week when exposed to normal ambient atmospheric conditions. With either chemical cleaning or Ar plasma cleaning after heating the sample in-situ to 150 °C for 90 minutes or 250 °C for 40 hours, almost all of the surface oxide was removed. For these surfaces a QE of 4.10-5 or better was measured. Oxygen plasma cleaning at 100% and 20% power produced CuO layer with surface carbon contaminant to 3 atomic %, however in-situ thermal cycling resulted in at best a QE of 3·10-6.
Organisation ASTeC , STFC
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Language English (EN)
Type Details URI(s) Local file(s) Year
Paper In Conference Proceedings In 9th International Particle Accelerator Conference (IPAC18), Vancouver, Canada, 29 Apr 2018 - 4 May 2018, (2018): 3865-3868. http://accelconf.…/papers/thpal095.pdf 2018