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@ARTICLE{Schneidmiller:582403,
      author       = {Schneidmiller, Evgeny Alexanrdovich and Dreimann, Matthias
                      and Kuhlmann, Marion and Rönsch-Schulenburg, Juliane and
                      Zacharias, Helmut},
      title        = {{G}eneration of {U}ltrashort {P}ulses in {XUV} and {X}-ray
                      {FEL}s via an {E}xcessive {R}everse {U}ndulator {T}aper},
      journal      = {Photonics},
      volume       = {10},
      number       = {6},
      issn         = {2304-6732},
      address      = {Basel},
      publisher    = {MDPI},
      reportid     = {PUBDB-2023-01949},
      pages        = {653},
      year         = {2023},
      abstract     = {The pulse duration in short-pulse schemes for
                      Self-Amplified Spontaneous Emission Free Electron Lasers
                      (SASE FELs) is limited by the FEL coherence time. A recently
                      proposed concept allows to overcome the coherence time
                      barrier and to get much shorter pulses. When the lasing part
                      of an electron bunch is much shorter than the coherence
                      time, one can suppress the radiation in the long main
                      undulator while preserving microbunching within that short
                      lasing slice. Then a short radiation pulse is produced in a
                      relatively short radiator. A possible suppression method, an
                      excessive reverse undulator taper, is discussed and
                      illustrated numerically in this paper. We also performed
                      first experimental tests of this method at the soft X-ray
                      FEL user facility FLASH. The measured pulse duration
                      approaches 1 fs (FWHM) at the wavelength of 5 nm.},
      cin          = {MPY / FS-FLASH / FS-FLASH-O / DOOR ; HAS-User / MFL},
      ddc          = {530},
      cid          = {I:(DE-H253)MPY-20120731 / I:(DE-H253)FS-FLASH-20140814 /
                      I:(DE-H253)FS-FLASH-O-20160930 /
                      I:(DE-H253)HAS-User-20120731 / I:(DE-H253)MFL-20120731},
      pnm          = {621 - Accelerator Research and Development (POF4-621) / 6G2
                      - FLASH (DESY) (POF4-6G2)},
      pid          = {G:(DE-HGF)POF4-621 / G:(DE-HGF)POF4-6G2},
      experiment   = {EXP:(DE-H253)FLASHII(machine)-20150901},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:001015702300001},
      doi          = {10.3390/photonics10060653},
      url          = {https://bib-pubdb1.desy.de/record/582403},
}