Author: Feifel, R.
Paper Title Page
Generation and Measurement of Intense Few-Femtosecond Superradiant Soft X-Ray Free Electron Laser Pulses  
  • S. Spampinati, E. Allaria, L. Badano, C. Callegari, G. De Ninno, M. Di Fraia, S. Di Mitri, L. Giannessi, N. Mahne, M. Manfredda, N.S. Mirian, G. Penco, O. Plekan, K.C. Prince, L. Raimondi, P. Rebernik Ribič, C. Spezzani, M. Trovò, M. Zangrando
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • R. Feifel, R. Squibb
    Uppsala University, Uppsala, Sweden
  • T. Mazza
    EuXFEL, Hamburg, Germany
  • X. Yang
    BNL, Upton, New York, USA
  Intense FEL VUV and soft X-ray pulses with a time duration of few fs allows to probe ultrafast, out-of equilibrium dynamics or to pump the sample driving new phase transitions in regimes where uniform heating is not depleted by secondary energy decay channels, such as Auger effect [Principi]. Most of the methods proposed to reduce the FEL pulse duration are based on a manipulation of longitudinal electron beam properties such as emittance, beam current, energy spread, trajectory or optical functions. We present an attractive alternative based on the exploitation of the FEL dynamic process itself, driving the FEL amplifier in saturation and superradiance in a cascade of undulators resonant at higher harmonics of an initial seed. At FERMI we have implemented for the first time a multistage superradiant cascade reaching EUV-soft X-ray wavelengths and producing high-power, stable, FEL pulses with a duration of about 5 fs. We report here the analysis of the configuration used and of the characterization of the radiation produced in this regime.  
slides icon Slides TUB04 [3.300 MB]  
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