New results of the high-gain harmonic generation free-electron laser experiment

We report on the experimental investigation of high-gain harmonic generation carried out at the Accelerator Test Facility at Brookhaven National Laboratory. A seed CO, laser at a wavelength of 10.6 mum was used to generate FEL output at a 5.3-mum wavelength. The duration of the output pulse was measured using a second-harmonic intensity autocorrelator, and the coherence length was measured using an interferometer. We also measured the energy distribution of the electron beam after it exited the second undulator, observing behavior consistent with that is expected at saturation. The intensity of the harmonic components of the output at 2.65 and 1.77 mum was determined relative to that of the 5.3- Lm fundamental. Finally, using a corrector magnet upstream of the radiator, steering effects on the trajectories of the electron and light beams were studied. (C) 2001 Elsevier Science B.V. All rights reserved.