Author: Görler, M.
Paper Title Page
THPA18 Operation of the FLASH Photoinjector Laser System 507
 
  • S. Schreiber, M. Görler, K. Klose, T. Schulz, M. Staack
    DESY, Hamburg, Germany
  • G. Klemz, G. Koss
    DESY Zeuthen, Zeuthen, Germany
  • I.H. Templin, I. Will, H. Willert
    MBI, Berlin, Germany
 
  The pho­toin­jec­tor of FLASH uses an RF gun equipped with cae­sium tel­luride pho­to­cath­odes il­lu­mi­nated by ap­pro­pri­ate UV laser pulses as a source of ul­tra-bright elec­tron beams. The su­per­con­duct­ing ac­cel­er­a­tor of FLASH is able to ac­cel­er­ate thou­sands of elec­tron bunches per sec­ond in burst mode. This puts spe­cial de­mands on the de­sign of the elec­tron source, es­pe­cially the laser sys­tem. The fully diode pumped laser sys­tem is based on Nd:YLF and pro­duces a train of 2400 UV pulses in a burst of 0.8 ms length with a rep­e­ti­tion rate of 5 Hz and 800 pulses with 10 Hz. The sin­gle pulse en­ergy is up to 25 μJ per pulse at 262 nm. The laser uses a pulsed os­cil­la­tor syn­chro­nized to the mas­ter RF with a sta­bil­ity of bet­ter than 200 fs in ar­rival time at the RF gun. Spe­cial care has been taken to pro­duce a uni­form and sta­ble pulse train in terms of pulse en­ergy, shape, and phase. Since FLASH is a free-elec­tron laser user fa­cil­ity, the laser is de­signed to op­er­ate for more than 8000 h per year with­out op­er­a­tor in­ter­ven­tion and lit­tle main­te­nance. We re­port on op­er­a­tional ex­pe­ri­ence with the new sys­tem brought in op­er­a­tion in spring 2010.