The photocathode laser was investigated for the generation of high current electron beam to be used in a high power infrared free electron laser.
The photocathode laser consisted of an additive pulse mode-locked Nd:YLF oscillator, Faraday isoltor, pulse slicer and 20 mm Nd:glass amplifier. The APM Nd:YLF oscillator generates pulses with pulse width of 1.8 ps, a pulse interval of 10 ns and an average power of 150 mW. The pulse slicer consisted of arbitrary waveform function generator, fast high voltage amplifier and Pockels cell. A macropulse with 10 s width, containing 1000 micropulse, was produced by this pulse slicer. The macropulse was amplified by a five-pass Nd:glass amplifier.
The amplified single micropulse reached an energy of 43 μJ, given an amplification of 24000 (43 μJ/1.8 nJ) and the envelope of macropulse was maintained uniformly in five-pass Nd:galss amplifier. The amplified pulse train, after converting to UV by nonlinear crystals, will be utilized for the generation of high current photoelectron beam.