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@PHDTHESIS{Kononenko:408109,
      author       = {Kononenko, Olena},
      othercontributors = {Foster, Brian and Palmer, Charlotte},
      title        = {{C}ontrolled injection into a {L}aser-driven wakefield
                      accelerator},
      school       = {Universität Hamburg},
      type         = {Dissertation},
      address      = {Hamburg},
      publisher    = {Verlag Deutsches Elektronen-Synchrotron},
      reportid     = {PUBDB-2018-02673, DESY-THESIS-2018-027},
      series       = {DESY-THESIS},
      pages        = {179},
      year         = {2018},
      note         = {Dissertation, Universität Hamburg, 2018},
      abstract     = {This thesis explores laser-driven plasma-wakefield
                      acceleration using two different high-power,ultrashort
                      titanium-doped sapphire lasers. The first experiment was
                      performed at the CentralLaser Facility in the Rutherford
                      Appleton Laboratory using the petawatt class Astra
                      GEMINIlaser, focused by an F/40 focusing optic, and a
                      two-stage, variable-length (< 42mm) gas targetfilled with a
                      gas mixture to generate electron beams with charge greater
                      100 pC and accelerateto above 1 GeV. In this work,
                      two-dimensional (2D) hydrodynamic simulations were
                      performed, using the opensource fluid code OpenFOAM, to
                      simulate the plasma-density distribution and study
                      possiblesources of instability and unwanted effects occuring
                      during the electron injection and acceleration,which might
                      be adjusted in future by improvement of the plasma target
                      design. Experimentaldata describing the properties of the
                      electron bunch obtained with the variable-length target,have
                      been analysed with respect to the properties of the target,
                      including aperture diameter andinlet pressure. Plasma
                      density modulations along the laser propagation axis lead to
                      plasma-waketransverse oscillations and are expected to
                      negatively impact stability.The other experiment was
                      performed in the BOND laboratory at DESY, utilising the new
                      25 TW, 25 fs, Ti:Sa laser, which is focused by an F/14
                      off-axis parabolic mirror (OAP), onto a gastarget, reaching
                      a peak intensity of 10$^{19}$W/cm$^{2}(a_{0}\simeq$ 2:2).
                      Using either a gas capillary target ora supersonic gas jet,
                      electrons were accelerated up to energies exceeding 100 MeV.
                      These beamsexhibit a wide range of different charges. A
                      cavity-based charge diagnostic, named DaMon,which has much
                      better sensitivity than commercially available integrated
                      current transformers,was tested.Simultaneous use of the
                      DaMon together with a scintillating screen allowed estimates
                      ofbunch charge, and showed that the sensitivity of the DaMon
                      to beam position was negligible.Results from experiments
                      with a 10 mm gas cell demonstrated detection of 25 $\pm$ 9
                      fC electronbunches, which is the lowest charge reported at
                      the exit of a plasma wakefield accelerator. Acomparison of
                      the electron-beam charge measured by the DaMon and the
                      electron spectrometerdemonstrated that the DaMon has a
                      significant advantage in acceptance angle compared to thatof
                      the electron spectrometer, which is of crucial importance
                      for a total charge measurement.},
      cin          = {FLA},
      cid          = {I:(DE-H253)FLA-20120731},
      pnm          = {631 - Accelerator R $\&$ D (POF3-631) / VH-VI-503 - Plasma
                      wakefield acceleration of highly relativistic electrons with
                      FLASH $(2015_IFV-VH-VI-503)$ / PHGS, VH-GS-500 - PIER
                      Helmholtz Graduate School $(2015_IFV-VH-GS-500)$},
      pid          = {G:(DE-HGF)POF3-631 / $G:(DE-HGF)2015_IFV-VH-VI-503$ /
                      $G:(DE-HGF)2015_IFV-VH-GS-500$},
      experiment   = {EXP:(DE-H253)FLASHForward-20150101},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      doi          = {10.3204/PUBDB-2018-02673},
      url          = {https://bib-pubdb1.desy.de/record/408109},
}