TUP1WA —  WG-A   (06-Mar-18   14:00—15:30)
Chair: T.O. Raubenheimer, SLAC, Menlo Park, California, USA
Paper Title Page
Generation of Atto-Second FELs  
  • A. Marinelli
    SLAC, Menlo Park, California, USA
  Sub-fs X-ray pump/probe capabilities hold great promise for understanding the role of coherent electron dynamics in molecules and solids. At the Linac Coherent Light Source (LCLS) for hard X-ray energies the sub-fs regime can be reached by shortening the electrong bunch and operating the FEL in the single-spike SASE FEL limit. In the soft X-ray region, achieving sub-fs pulses requires bandwidth broadening by means of an enhanced SASE scheme. In this talk I will present recent results on the generation of sub-fs X-ray pulses at LCLS and discuss the path to time-resolved experiments with attosecond time resolution  
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Ultrashort Pulse Generation and Superradiance in FELs  
  • X. Yang
    BNL, Upton, Long Island, New York, USA
  • L. Giannessi
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  The generation of a single X-ray isolated spike of radiation with peak power at multi-GW level and femtosecond temporal duration represents an almost unique opportunity in time resolved diffraction imaging of isolated molecules or non-periodic structures, for the possibility of acquiring single shot images before the Coulomb explosion of the sample takes place. Such a condition is met by an FEL operating in superradiant regime when the pulse has a self-similar shape deriving from the combined dynamics of saturation and slippage of the radiation over fresh electrons. We show that the peak of the pulse moves at superluminal speed similarly to the case of pulses propagation in anomalous dispersive active media and it is followed by a long pedestal resulting from the complex dynamics occurring in the tail after saturation. We analyze the dynamical conditions leading to the formation of the main pulse and the following tail and we study the correlation of the tail structure with the longitudinal phase space of the e-beam, providing recipes to partially suppress it.  
slides icon Slides TUP1WA02 [5.300 MB]  
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Free-Electron Laser R&D in the UK - Steps Towards a National X-FEL Facility  
  • N. Thompson, J.A. Clarke, D.J. Dunning
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • J.A. Clarke, D.J. Dunning
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • B.W.J. MᶜNeil
    USTRAT/SUPA, Glasgow, United Kingdom
  In this contribution we present highlights of FEL R&D in the UK with a focus on progress towards a national X-Ray FEL user facility. We discuss the aims and status of CLARA, a dedicated FEL test facility under construction at STFC Daresbury Laboratory and present highlights of recent research into the development of novel FEL output possibilities.  
slides icon Slides TUP1WA03 [9.028 MB]  
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