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SLAC Publication: SLAC-PUB-15020
SLAC Release Date: May 16, 2012
RF Gun Photocathode Research at SLAC
Jongewaard, Erik.
LCLS is presently operating with a third copper photocathode in the original rf gun, with a quantum efficiency (QE) of ~1x10^-4 and projected emittance gamma epsilon x,y almost equal to 0.45 mu m at 250 pC bunch charge. The spare LCLS gun is installed in the SLAC Accelerator Structure Test Area (ASTA), fully processed to high rf power. As part of a wider photocathode R&D program, a UV laser system and additional gun diagnostics are being installed at ASTA to measure QE, QE lifetime, and electron... Show Full Abstract
LCLS is presently operating with a third copper photocathode in the original rf gun, with a quantum efficiency (QE) of ~1x10^-4 and projected emittance gamma epsilon x,y almost equal to 0.45 mu m at 250 pC bunch charge. The spare LCLS gun is installed in the SLAC Accelerator Structure Test Area (ASTA), fully processed to high rf power. As part of a wider photocathode R&D program, a UV laser system and additional gun diagnostics are being installed at ASTA to measure QE, QE lifetime, and electron beam emittance under a variety of operating conditions. The near-term goals are to test and verify the spare photocathode production/installation sequence, including transfer from the final holding chamber to the rf gun. Mid- and longer-term goals include development of a rigorous understanding of plasma and laser-assisted surface conditioning and investigation of new, high-QE photocathode materials. In parallel, an x-ray photoemission spectroscopy station is nearing completion, to analyze Cu photocathode surface chemistry. In this paper we review the status and anticipated operating parameters of ASTA and the spectroscopy test chamber. Show Partial Abstract
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  • Interest Categories: Accelerator Physics, X-Ray Free Electron Laser