Speaker
Description
During the last run, the CLARA accelerator ran with a 2.5 cell 10 Hz S-band RF gun which had a modified back plate to allow the use of INFN-style photocathode pucks. Previously this gun had used a solid wall back plate that also acted as the photocathode*.
This presentation describes the different photocathodes that were used during the run and the various methods employed to prepare them for use. An initial cathode which was based on a solid Mo puck with the thin film of Cu grown using magnetron sputtering was seen to give high initial QE but a very fast degradation rate. Subsequent cathodes were hybrids with a Mo body and a solid copper tip for the active area. Several cathodes prepared using alternative techniques were employed, giving varied initial QE and lifetime. The final cathode used had satisfactory QE and a long enough lifetime to deliver a six month period of beam exploitation for external facility users.
- D. Angal-Kalinin, et al, ‘Design, specifications, and first beam measurements of the compact linear accelerator for research and applications front end’ Physical Review Accelerators and Beams 23 (2020) 044801
** T.C.Q. Noakes, et al, ‘Photocathode preparation and characteristics of the electron source for the VELA/CLARA facility’ Proceedings of the International Particle Accelerator Conference 2018 (IPAC-18), THPMK063, 2018, Vancouver, Canada
Funding Agency
UKRI-STFC
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