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@PHDTHESIS{Steudel:829761,
      author       = {Steudel, Isabel},
      title        = {{P}erformance of {P}lasma {F}acing {M}aterials under
                      {T}hermal and {P}lasma {E}xposure},
      volume       = {370},
      school       = {RWTH Aachen},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2017-03395},
      isbn         = {978-3-95806-226-9},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {XVI, 150 S.},
      year         = {2017},
      note         = {Dissertation, RWTH Aachen, 2017},
      abstract     = {A relatively clean, safe, and promising solution to cover
                      the globally increasing energy demand but also to avoid
                      energy supply problems could be nuclear fusion. In recent
                      decades, this ambitious project, to make energy generation
                      via fusion possible, demanded a lot of work and the
                      construction of the experimental fusion reactor ITER (latin
                      for "the way") in Cadarache, South France, plays an
                      important role to the next big step forward. ITER, a large
                      scale experiment, will demonstrate the scientific and
                      technological feasibility of nuclear fusion and should test
                      all key technologies that are necessary for the next steps,
                      which will be a demonstration power plant (DEMO) and finally
                      a commercial fusion power plant. Furthermore, potential
                      plasma facing materials (PFMs) for in-vessel components have
                      to sustain heat fluxes, neutronic volumetric heating and
                      neutron activation, electromagnetic loads, and environment
                      and safety requirements just to list the most significant
                      ones. At this time beryllium and tungsten are the PFMs in
                      ITER, for DEMO it could be ferritic martensitic steel in
                      addition to tungsten. In this context, this work examines
                      two materials, tungsten und stainless steel, from the
                      material scientific point of view under ITER and DEMO
                      relevant heat and particle fluxes. Building on the results
                      of former works, pure tungsten was exposed in the linear
                      plasma device PSI-2 to sequential and simultaneous transient
                      thermal loads with absorbed power densities up to 0.76
                      GW/m² and pure deuterium plasma and deuterium plasma with 6
                      $\%$ helium content, respectively. Furthermore, base
                      temperatures of 400 °C and 730 °C were used and the pulse
                      number was limited to a maximum of 1000 to cover a wide
                      range of loading conditions within the available machine
                      time. The results of this campaign identified that the
                      microstructure, the order of exposure as well as the loading
                      parameters have a substantial impact on the surface
                      modification and damage behaviour and furthermore, that
                      deuterium and helium exacerbates the material performance
                      considerably. In addition, high pulse number tests ($\le$
                      100, 000 pulses) with deuterium plasma background and an
                      absorbed power density of 0.38 GW/m$^{2}$ were executed to
                      quantify fatigue effects. These experiments led not only to
                      tremendous plastic deformations, microstructural changes
                      like subgrain formation and recrystallisation, but also to
                      the formation of nanostructures and helium induced bubbles
                      below the sample surface. In matters of ITER, where more
                      than 106 transient events are expected, these results
                      indicate severe disturbances of the operation as well as
                      detractions of plasma facing components (PFCs).},
      cin          = {IEK-2},
      cid          = {I:(DE-Juel1)IEK-2-20101013},
      pnm          = {899 - ohne Topic (POF3-899) / HITEC - Helmholtz
                      Interdisciplinary Doctoral Training in Energy and Climate
                      Research (HITEC) (HITEC-20170406)},
      pid          = {G:(DE-HGF)POF3-899 / G:(DE-Juel1)HITEC-20170406},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/829761},
}