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@PHDTHESIS{Hirscht:222115,
      author       = {Hirscht, Julian},
      title        = {{F}emtosecond {E}lectron {D}iffraction: {N}ext generation
                      electron sources for atomically resolved dynamics},
      issn         = {1435-8085},
      school       = {Universität Hamburg},
      type         = {Dr.},
      address      = {Hamburg},
      publisher    = {Verlag Deutsches Elektronen-Synchrotron},
      reportid     = {PUBDB-2015-03078, DESY-THESIS-2015-032},
      series       = {DESY-THESIS},
      pages        = {238},
      year         = {2015},
      note         = {Universität Hamburg, Diss., 2015},
      abstract     = {Three instruments for femtosecond electron diffraction
                      (FED) experiments were erected, partially commissioned and
                      used for first diffraction experiments. The Relativistic
                      Electron Gun for Atomic Exploration (REGAE) was completed by
                      beamline elements including supports, a specimen chamber and
                      dark current or electron beam collimating elements such that
                      the commissioning process, including first diffraction
                      experiments in this context, could be started. The temporal
                      resolution of this machine is simulated to be 25 fs (fwhm)
                      short, while a transverse coherence length of 30 nm (fwhm)
                      is feasible to resolve proteins on this scale. Whether this
                      machine is capable of meeting these predictions or whether
                      the dynamics of the electron beam will stay limited by
                      accelerator components, is not finally determined by the end
                      of this work, because commissioning and improvement of
                      accelerator components is ongoing. Simultaneously, a compact
                      DC electron diffraction apparatus, the E-Gun 300, designed
                      for solid and liquid specimens and a target electron energy
                      of 300 keV, was built. Fundamental design issues of the high
                      potential carrying and beam generating components occurred
                      and are limiting the maximum potential and electron energy
                      to 120 keV. Furthermore, this is limiting the range of
                      possible applications and consequently the design and
                      construction of a brand new instrument began. The
                      Femtosecond Electron Diffraction CAmera for Molecular Movies
                      (FED-CAMM) bridges the performance problems of very high
                      electric potentials and provides optimal operational
                      conditions for all applied electron energies up to 300 keV.
                      The variability of gap spacings and optimized manufacturing
                      of the high voltage electrodes lead to the best possible
                      electron pulse durations obtainable with a compact DC setup,
                      that does not comprise of rf-structures. This third
                      apparatus possesses pulse durations just a few tenth
                      femtoseconds apart from the design limit of the highly
                      relativistic REGAE and combines the advantages of simplicity
                      and stability of a compact FED apparatus with the short
                      temporal resolution of femtosecond accelerators, which are
                      operated with or include rf structures. Simulations of the
                      electron beam dynamics and the fact that the apparatus is
                      stable in respect to high voltages and electric field
                      gradients above 27 MV/m allows the conclusion, that a
                      temporal resolution significantly below 100 fs (fwhm),
                      perhaps even shorter than 70 fs, can be achieved. This
                      instrument currently defines the state-of-the-art. Firstly,
                      because high voltage feedthrough for these potentials are
                      commercially still not available, with a subsequent limiting
                      of the potentials and consequent lowering of the electron
                      numbers per pulse as well as the pulse durations and
                      electron penetration. Secondly, this is because research
                      communities focus on photon and rf-based electron sources
                      for the achievement of sub-100 fs pulses, which typically
                      include timing-jitter. Here it is shown that simple DC
                      acceleration can lead to the same, satisfactory pulse
                      duration up to an energy of a few hundred keV, potentially
                      as high as 800 keV.},
      cin          = {MPSD / UNI/EXP},
      cid          = {I:(DE-H253)MPSD-20120731 / $I:(DE-H253)UNI_EXP-20120731$},
      pnm          = {631 - Accelerator R $\&$ D (POF3-631)},
      pid          = {G:(DE-HGF)POF3-631},
      experiment   = {EXP:(DE-H253)REGAE-20150101},
      typ          = {PUB:(DE-HGF)29 / PUB:(DE-HGF)11},
      doi          = {10.3204/DESY-THESIS-2015-032},
      url          = {https://bib-pubdb1.desy.de/record/222115},
}