Author: Vétéran, J.
Paper Title Page
TUPPP048 Increasing the Spectral Range of the CLIO Infrared FEL User Facility by Reducing Diffraction Losses 1709
  • J.-M. Ortega, G. Perilhous, R. Prazeres
  • H.B. Abualrob, P. Berteaud, L. Chapuis, M.-E. Couprie, T.K. El Ajjouri, F. Marteau, J. Vétéran
    SOLEIL, Gif-sur-Yvette, France
  • J.P. Berthet, F. Glotin
    CLIO/ELISE/LCP, Orsay, France
  Funding: CNRS/RTRA
The infrared free-electron laser offers a large tunability since the FEL gain remains high throughout the infrared spectral range, and the reflectivity of metal mirrors remains also close to 1. The main limitation comes from the diffraction of the optical beam due to the finite size of the vacuum chamber of the undulator. At CLIO, we have obtained previously* an FEL tunable from 3 to 150 μm by operating the accelerator between 50 and 14 MeV. However, we found that a phenomenon of “power gaps“ is observed in far-infrared : the laser power falls down to zero at some particular wavelengths, whatever the beam adjustments are. We showed that this effect is related to to the waveguiding effect of the vacuum chamber leading to different losses and power outcoupling at different wavelengths**. To alleviate this effect we have designed a new undulator allowing to use a larger vacuum chamber without reducing the spectral tunability and agility of the FEL. From simulations, a large increase of available power is expected in far-infrared. The new undulator has been installed and its performances and first FEL measurement in far-infrared will be presented
* J.M. Ortega, F. Glotin, R. Prazeres
Infrared Physics and Technology, 49, 133 (2006)
** R. Prazeres, F. Glotin, J.-M. Ortega
Phys. Rev. STAB12, 010701 (2009)