Author: Peters, F.
Paper Title Page
WEP046 The European XFEL Photocathode Laser 423
  • L. Winkelmann, A. Choudhuri, U. Grosse-Wortmann, I. Hartl, C. Li, C. Mohr, J. Müller, F. Peters, S. Pfeiffer, S.H. Salman
    DESY, Hamburg, Germany
  We present the Yb:fiber, Nd:YVO4 laser used to generate electrons from the RF photocathode gun at the European XFEL. The laser provides deep UV output pulses in 600 µs bursts with variable internal repetition rate (564 kHz to 4.5 MHz). Due to its robust architecture (mode-locked and synchronized fiber oscillator, Yb:fiber amplifiers and Nd:YVO4 gain blocks), the laser has operated with >99% uptime since January 2017. Using this laser, the XFEL reported energies of 17.5 GeV in July 2018, and simultaneous multi-mJ lasing in its three SASE beamlines. The laser offers two parallel outputs (1064 nm) with single pulse energies of >100 µJ and 11 ps width (FWHM). One output is converted to deep UV with efficiencies > 25%, and the second is used as a laser heater to reduce microbunching instabilities to increase SASE efficiency. Several state-of-art laser controls were implemented, including feed-forward algorithm to flatten electron charge along the bunch, active beam stabilization with < ±10 µm jitter at the photocathode, state machines for hands-off end-user operation, and temporal pulse synchronization and drift compensation to the timing jigger of the electron bunches to less than 45 fs.  
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About • paper received ※ 23 August 2019       paper accepted ※ 29 August 2019       issue date ※ 05 November 2019  
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