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@PHDTHESIS{Kiffer:360220,
      author       = {Kiffer, Markus},
      othercontributors = {Stöhlker, Thomas and Verdú Galiana, José and
                          Schmidt-Kaler, Ferdinand},
      title        = {{C}haracterisation and cooling of captured ensembles of
                      highly charged ions in a {P}enning trap},
      school       = {Friedrich-Schiller-Universität Jena},
      type         = {Dissertation},
      publisher    = {Friedrich-Schiller-Universität Jena},
      reportid     = {GSI-2025-00817},
      pages        = {140 p.},
      year         = {2025},
      note         = {Dissertation, Friedrich-Schiller-Universität Jena, 2025},
      abstract     = {The electric field experienced by bound electrons in highly
                      charged ions ranks among the strongest available to
                      experimental studies. For moderate atomic numbers, the
                      electric field in hydrogen-like ions is equivalent to
                      current laser systems. Quantitative interaction experiments
                      with ions require a single-species, well-controlled target.
                      In particular, the target’s ion distribution and density
                      must be characterised. This thesis addresses these
                      requirements by producing and characterising a suitable ion
                      target through dynamic capture in a Penning trap as part of
                      the High-Intensity Laser-Ion Trap Experiment. Three key
                      developments have been implemented. First, the ion optics
                      were upgraded to control the initial conditions of the
                      incoming ion bunches. Second, a phosphor screen detector was
                      introduced to measure the radial distribution of the
                      captured ion ensembles. Finally, a new Penning trap setup
                      featuring a dedicated dual-electrode resonator was developed
                      and integrated into the experiment. The presented
                      experimental results demonstrate that the ion ensemble
                      reaches maximum radial density when the incoming ions are
                      aligned with the central axis. Under these conditions, the
                      radial thermalisation process occurs within 50 μs;
                      resulting in a Gaussian-shaped radial distribution
                      characteristic of a weakly coupled ion ensemble in thermal
                      equilibrium. In the axial direction, the applied resonator
                      facilitates the resistive cooling process of the captured
                      ions, reducing the centre-of-mass energy by more than 99
                      $\%$ within 30 to 100 ms. A model is developed to describe
                      the time-resolved induced signal during resistive cooling.
                      From this model, key parameters such as the ion number and
                      axial equilibrium energy are extracted. The combination of
                      these radial and axial results yields an estimated peak
                      density of 50 000 per cubic millimetre. For an upcoming
                      tunnel ionisation experiment, ionisation yields are
                      estimated, with more than 100 ionisations expected per laser
                      pulse.},
      keywords     = {Penning-Käfig (Other) / Ion (Other) / 530 (Other)},
      cin          = {PTS},
      cid          = {I:(DE-Ds200)PTS-20220701OR463},
      pnm          = {631 - Matter – Dynamics, Mechanisms and Control
                      (POF4-631)},
      pid          = {G:(DE-HGF)POF4-631},
      experiment   = {$EXP:(DE-Ds200)External_experiment-20200803$},
      typ          = {PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:gbv:27-dbt-66345-2},
      doi          = {10.22032/DBT.66345},
      url          = {https://repository.gsi.de/record/360220},
}