Author/Authors :
Jaroszynski، نويسنده , , D.A. and Prazeres، نويسنده , , R and Glotin، نويسنده , , F and Marcouillé، نويسنده , , O and Ortega، نويسنده , , J.M. and Oepts، نويسنده , , D and van der Meer، نويسنده , , A.F.G. and Knippels، نويسنده , , G.M.H and van Amersfoort، نويسنده , , P.W، نويسنده ,
Abstract :
We present measurements of the temporal and spectral properties of radiation produced from the step-tapered undulator infrared free-electron lasers (FELs), CLIO in France and FELIX in the Netherlands. Using a two section undulator with independently adjustable deflection parameters, K, the FEL will operate either with an enhanced efficiency and improved spectral properties (with a small positive ΔK step) or simultaneously at two frequencies (for large ΔK). Using a dispersion-free hole output coupler the maximum wavelength difference δλλ, has now been extended to more than δλλ ≈ 0.6. We also present measurements that show that the FEL FELIX will produce significant power simultaneously at two wavelengths by coherent spontaneous emission when the wavelength is long and the electron bunch is short. The efficiency, spectral and temporal properties have been measured. We show that at the maximum efficiency, ΔK ≈ 0.02, the optical pulses generated are smooth and close to Fourier transform limited. By adjusting ΔK the optical pulse duration can be varied by a factor of 2 or more and sidebands due to synchrotron oscillations can be suppressed.
