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@PHDTHESIS{Eichner:596960,
      author       = {Eichner, Timo},
      othercontributors = {Maier, Andreas and Kärtner, Franz},
      title        = {{I}mproved {P}ulse {C}haracteristics and {P}ower {S}caling
                      of {D}rive {L}asers for {L}aser-{W}akefield {A}cceleration},
      school       = {Universität Hamburg},
      type         = {Dissertation},
      address      = {Hamburg},
      publisher    = {Verlag Deutsches Elektronen-Synchrotron DESY},
      reportid     = {PUBDB-2023-06337, DESY-THESIS-2023-015},
      series       = {DESY-THESIS},
      pages        = {192},
      year         = {2023},
      note         = {Dissertation, Universität Hamburg, 2023},
      abstract     = {Laser-wakefield acceleration (LWFA) is a promising,
                      emerging technology for future accelerator-based X-ray light
                      sources, which are essential tools in various fields of
                      science, industry and medicine. In laser-wakefield
                      acceleration, an intense laser pulse drives a plasma wave
                      that supports high accelerating field gradients. This allows
                      electrons to be accelerated over distances that are orders
                      of magnitude shorter than in conventional
                      radio-frequency-based particle accelerators. Driving
                      high-brightness, accelerator-based X-ray sources requires
                      lasers with a peak power around 100TW, and well-controlled
                      pulse properties, since of the quality of the accelerated
                      electron beams is sensitive to the properties of the driving
                      laser pulse. For LWFA to become truly competitive with
                      current radio-frequency-based accelerators, the stability
                      and pulse quality of the lasers must be further improved,
                      and their repetition rate must be increased from the current
                      few Hz to the kHz range, thereby raising the average power
                      to the kW level. The challenges that need to be solved to
                      achieve this lie in the design of the laser amplifiers, the
                      pump lasers for those amplifiers, the final pulse compressor
                      of chirped pulse amplification systems, and an overall
                      improvement of the pulse quality and stability in all
                      sub-components of the laser.This thesis outlines a path
                      towards future high repetition rate LWFA drivers by studying
                      these challenges throughout the amplification chain of
                      Ti:sapphire-based lasers. This starts with the generation of
                      the seed pulse, which largely determines the properties of
                      the final, fully amplified pulse. To deliver high quality
                      seed pulses, a laser front-end based on optical parametric
                      chirped pulse amplification (OPCPA) is presented. The
                      technology can deliver pulses with high temporal contrast
                      and flexible spectral properties, which make it an
                      attractive option for seeding Ti:sapphire amplifiers.
                      However, achieving high beam quality and stability is
                      challenging for OPCPA. A thorough experimental and
                      theoretical study of the saturation dynamics of OPCPA, and
                      the use of advanced control methods, allow to combine these
                      features and as a result, the present an OPCPA system
                      exhibits both, unprecedented long-term stability and
                      excellent spatio-temporal pulse quality.Further, the thermal
                      management of high average power Ti:sapphire amplifiers is
                      investigated, leading to a conceptual design for a
                      Joule-level amplifier that will provide a high quality beam
                      for the first 100Hz operation of a high energy laser
                      wakefield accelerator. For future scaling to kHz repetition
                      rates, the thesis further studies the high average power
                      frequency doubling of ytterbium:doped multi-core fiber
                      lasers, a highly scalable technology, which is a potential
                      solution for providing the 10 kW- level average power pump
                      beams required for future 100 TW, 1 kHz Ti:sapphire laser
                      systems.Finally, the thermal limitations of gold-coated
                      pulse compression gratings are studied, where absorption in
                      the gold coating can cause thermal deformation of the
                      gratings. A custom numerical model is developed to show that
                      this deformation can degrade the spatio-temporal quality of
                      the compressed pulses already at the few-Watt level, and as
                      a result, other grating technologies will be required in
                      future multi-kW drive lasers for laser-wakefield
                      acceleration.},
      cin          = {MLS},
      cid          = {I:(DE-H253)MLS-20210107},
      pnm          = {621 - Accelerator Research and Development (POF4-621)},
      pid          = {G:(DE-HGF)POF4-621},
      experiment   = {EXP:(DE-H253)KALDERA-20221201},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      doi          = {10.3204/PUBDB-2023-06337},
      url          = {https://bib-pubdb1.desy.de/record/596960},
}