Research of the drive laser for FEL

In order to achieve high quality and high brightness electron beam,a photocathode injector is used as the electron source in the experimental setup of a free electron laser (FEL).The drive laser system is a master oscillator power amplifier configuration,consisting of a confinuous wave diode-pumped mode-locked oscillator,one double-pass and two single-pass regenerative diode-pumped pulse amplifiers and a four fold frequency conversion part.After adjustment,single micropulse energy of 4μJ with less than 3 percent of jitter at wavelength 266nm was obtained.These micropulses were contained within a macropulse envelope as long as 2μs to 6μs.In the experiments,adopting C2Te photocathode as the photoinjector,more than 40A electron beam was obtained,meeting the requirement of beam current for the FEL.