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@MASTERSTHESIS{Hrsch:477117,
      author       = {Hörsch, Julian Michael},
      othercontributors = {Osterhoff, Jens and Hillert, Wolfgang},
      title        = {{E}lectron {T}emperature {M}easurements in {D}ischarge
                      {C}apillaries},
      school       = {Universität Hamburg},
      type         = {Masterarbeit},
      address      = {Hamburg},
      publisher    = {Verlag Deutsches Elektronen-Synchrotron DESY},
      reportid     = {PUBDB-2022-01913, DESY-THESIS-2022-009},
      series       = {DESY-THESIS},
      pages        = {96},
      year         = {2022},
      note         = {Masterarbeit, Universität Hamburg, 2022},
      abstract     = {The electron temperature of hydrogen and argon plasmas,
                      that were produced at gas pressures of a few millibar and
                      with electron densities in the range of $1\times10^{15}
                      \text{cm}^{-3}$ to $1\times10^{17} \text{cm}^{-3}$, were
                      investigated. These working points are typical of plasma
                      sources which are used in beam-driven plasma wakefield
                      accelerators such as FLASHForward. The particular plasmas
                      were produced with a high voltage discharge inside a
                      sapphire capillary that allowed, by means of their
                      transparency, optical emission spectroscopy measurements. To
                      determine the electron temperature emission lines were
                      measured and the Boltzmann plot method, which requires
                      optical thin emission lines and partial local thermodynamic
                      equilibrium (pLTE), applied. These requirements were
                      discussed and it was shown that the argon plasma is likely
                      to exhibit stronger deviations than the hydrogen plasma. In
                      hydrogen the maximum electron temperature could be
                      successfully determined to $1.6\pm0.40 \text{eV}$ and this
                      with significantly smaller uncertainties than in previous
                      measurements. For argon this method was less successful and
                      yielded un-physical results. This was in agreement with
                      possibly stronger deviations from the pLTE conditions for
                      argon and necessitated the implementation of a more complex
                      collisional radiative model (CRM) for the temperature
                      determination. The temperatures resulting from the CRM
                      approach were similar to those obtained with the Boltzmann
                      plot analysis and could therefore not improve the results.
                      With these first results this study has laid the ground-work
                      for the electron temperature characterisation in discharge
                      capillaries for FLASHForward, which is a key for improving
                      electron density measurements, plasma modelling and future
                      active plasma lenses.},
      cin          = {$HH_FH_FTX_AS$ / MPA2 / $XFEL_DO_DD_DA$},
      cid          = {$I:(DE-H253)HH_FH_FTX_AS-20210421$ /
                      I:(DE-H253)MPA2-20210408 /
                      $I:(DE-H253)XFEL_DO_DD_DA-20210408$},
      pnm          = {621 - Accelerator Research and Development (POF4-621)},
      pid          = {G:(DE-HGF)POF4-621},
      experiment   = {EXP:(DE-H253)FLASHForward-20150101},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)19},
      doi          = {10.3204/PUBDB-2022-01913},
      url          = {https://bib-pubdb1.desy.de/record/477117},
}