h1

% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@PHDTHESIS{Barthels:1020821,
      author       = {Barthels, Thilo},
      othercontributors = {Häfner, Constantin Leon and Bergs, Thomas},
      title        = {{P}rozessführung bei stark parallelisierten
                      {UKP}-{B}earbeitungsprozessen für {M}etallfolien},
      school       = {Rheinisch-Westfälische Technische Hochschule Aachen},
      type         = {Dissertation},
      address      = {Aachen},
      publisher    = {RWTH Aachen University},
      reportid     = {RWTH-2025-09257},
      pages        = {1 Online-Ressource : Illustrationen},
      year         = {2025},
      note         = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
                      University 2026; Dissertation, Rheinisch-Westfälische
                      Technische Hochschule Aachen, 2025},
      abstract     = {The subject of this dissertation is the scaling of
                      productivity through a multi-beam pro-cessing approach using
                      ultrashort pulsed (USP) laser radiation. For this purpose, a
                      modeling system for the determination of system and process
                      parameters for multi-beam processing is derived. Input
                      variables such as the number of structures, the structure
                      size, the ablation depth and the ablation volume, as well as
                      the material and the maximum pulse energy of the laser are
                      taken into account. With the aim of in-creasing productivity
                      in the parallel micro structuring of thin metal foils, the
                      number of realizable partial beams, the range of repetition
                      rate, partial beam fluence to be used, as well as the track
                      and pulse overlap for a qualitative processing result are
                      derived as output variables of the modeling system. The
                      approach chosen to achieve the goal of qualitative
                      productivity scaling is divided into three subsections:
                      single-beam processing, a data-based computational
                      productivity model based on more than 3,000 single-beam
                      experiments and the determination of qualitative limits to
                      the scalability of multi-beam processing. The first
                      limitations of the productivity increase are worked out
                      using single-beam processing. It is modeled that
                      productivity is primarily maximized with a reduced partial
                      beam fluence and an increasing number of partial beams. As a
                      secondary condition, the number of structures to be produced
                      is important in order to reduce the number of multi-beam
                      processing passes to a minimum. The evaluation of the
                      quality limits of multi-beam processing shows that, in
                      addition to the investigated process parameters of partial
                      beam fluence, repetition rate, track and pulse overlap, the
                      framework conditions not defined by the laser, such as
                      sample holder, process gas or extraction, have greatest
                      influence on quality. Two variables, the available thermal
                      mass for heat absorption and dissipation and keeping the
                      processing field clean by efficiently removing
                      process-related ablation products, are essential here.
                      Convection cooling using process gas and diffusion cooling
                      using a sample holder with full-surface contact to the metal
                      foil is important, as this increases the heat dissipation
                      for the available thermal mass. Ex-traction of the removal
                      products only has an effect on cleanliness. If the thermal
                      mass is not sufficient or a critical removal volume flow
                      occurs, this leads to negative thermal effects. Primarily
                      due to an excessively high repetition rate, foil bulge under
                      increased thermal load or recondensed ablation products form
                      an irreversible bond on already structured surfaces. A
                      process map for the design of productive and qualitative
                      system and process parameters for parallelized ultrashort
                      pulse laser machining processes has emerged from the model
                      and experiments, which are based on the ablation efficiency
                      curve of metals known in the single beam approach according
                      to NEUENSCHWANDER and RACIUKAITIS. Under the constraints of
                      the laser beam source and the optical system to be used, a
                      design and process control recommendation for USP multi-beam
                      processes is made possible. A maximization of the number of
                      partial beams at a partial beam fluence of 2 to 4 times the
                      most efficient single beam fluence and repetition rates of
                      ≤ 50 to 100 kHz are recommended for scaling through
                      multi-beam processing.},
      cin          = {418710},
      ddc          = {620},
      cid          = {$I:(DE-82)418710_20140620$},
      typ          = {PUB:(DE-HGF)11},
      doi          = {10.18154/RWTH-2025-09257},
      url          = {https://publications.rwth-aachen.de/record/1020821},
}