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@INPROCEEDINGS{Unterberg:891688,
      author       = {Unterberg, B. and Zlobinski, Miroslaw and De Temmerman, G.
                      and Porosnicu, C. and Matveev, D. and Sergienko, G. and
                      Brezinsek, S. and Nicolai, D. and Rasinski, M. and Spilker,
                      B. and Freisinger, M. and Möller, S. and Linsmeier, Ch. and
                      Lungu, C. P. and Dinca, P.},
      title        = {{S}tability of deuterated beryllium layers on tungsten
                      substrates during transient heat loads by laser irradiation},
      reportid     = {FZJ-2021-01671},
      year         = {2021},
      abstract     = {24th Int. Conf. on Plasma Surface Interaction in Fusion
                      Devices (PSI-24) in Jeju, Korea, May 31st to June 5th, 2020
                      Stability of deuterated beryllium layers on tungsten
                      substrates during transient heat loads by laser
                      irradiationB. Unterberga, M. Zlobinskia,*, G. De Temmermanb,
                      C. Porosnicuc, D. Matveeva, G. Sergienkoa, S. Brezinseka, D.
                      Nicolaia, M. Rasinskia, B. Spilkera, M. Freisingera, S.
                      Möllera, Ch. Linsmeiera, C. P. Lunguc, P. Dincac aInstitute
                      of Energy and Climate Research – Plasma Physics,
                      Forschungszentrum Jülich GmbH (FZJ), Partner in the
                      Trilateral Euregio Cluster, D-52425 Jülich, GermanybITER
                      Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St
                      Paul Lez Durance Cedex, FrancecNational Institute for Laser,
                      Plasma and Radiation Physics (INFLPR), Atomistilor 409,
                      Magurele, Jud Ilfov, 077125, Bucharest,
                      Romaniab.unterberg@fz-juelich.deA major contribution to
                      long-term hydrogen retention in ITER is expected in Be
                      layers on W divertor components [1]. Therefore, for ITER an
                      in-situ and spatially resolved diagnostic of in-vessel
                      retention has been qualified based on laser induced
                      desorption (LID) of tritium out of Be co-deposits [2]. In
                      this context, the stability of such layers is important in
                      view of possible dust production and flaking.Homogeneous Be
                      layers with different deuterium content (0.01-0.3 D/Be) and
                      layer thicknesses (1-20 μm) were deposited on W substrates
                      by HiPIMS (High Power Impulse Magnetron Sputtering) [3]. The
                      laser irradiation parameters have been varied between 0.5
                      and 5.0 MJ/m2 (diameter of the laser beam at the sample of 3
                      mm) with pulse lengths between 1 and 20 ms. Such loading
                      parameters also cover the power load densities during ELMs
                      in ITER. The surface temperature was monitored by a
                      pyrometer and ranged between 900 and 2300 K.Overall, the
                      stability of the Be layer is mostly governed by the
                      operational conditions during the coating process within the
                      magnetron. Best adhesion has been obtained for a surface
                      roughness of 150 nm of the substrate, chemical surface
                      cleaning and in-situ cleaning via GDC, and layer deposition
                      at a rate of 0.2 nm/s. These layers withstand the strongest
                      laser pulses even above melting onset without significant
                      detachment of layer fragments. Crack networks can be
                      observed below melting which are connected to tension during
                      the cool-down phase of the layer. When the deposition was
                      performed on less rough substrates (10-15 nm) with DC
                      deposition either the layer is fragmented in microscopic
                      parts, which are delaminated to a large extent, or even
                      complete macroscopic lamination is observed with a clear
                      separation into mm-sized delaminated areas with no remaining
                      layer fragments and remaining layer. SEM pictures show
                      hill-like structures on the μm scale with local
                      delamination surrounded by cracks. The different damage
                      categories can also be distinguished via the temperature
                      increase during the laser pulse: for macroscopic
                      delamination the pyrometer shows a steep temperature
                      increase until delamination, for microscopic delamination
                      the temperature still increases fasterthan on the best, most
                      adhesive layer, governed by the heat contact between layer
                      and substrateas described for plasma deposited carbon layers
                      in [4]. [1] S. Brezinsek, et al., Nucl. Fusion 55, 063021
                      (2015)[2] M. Zlobinski et al., Nuclear Materials and Energy,
                      Volume 19, May 2019, Pages 503-509[3] P. Dinca, et al.,
                      Surface $\&$ Coatings Tech. 321 (2017) 397-402[4] A.
                      Herrmann, Phys. Scr. T128 (2007) 234–238},
      month         = {Jan},
      date          = {2021-01-25},
      organization  = {24th International Conference on
                       Plasma Surface Interactions in
                       Controlled Fusion Devices (PSI 2020),
                       virtuell (virtuell), 25 Jan 2021 - 29
                       Jan 2021},
      cin          = {IEK-4 / IEK-1},
      cid          = {I:(DE-Juel1)IEK-4-20101013 / I:(DE-Juel1)IEK-1-20101013},
      pnm          = {134 - Plasma-Wand-Wechselwirkung (POF4-134)},
      pid          = {G:(DE-HGF)POF4-134},
      typ          = {PUB:(DE-HGF)1},
      url          = {https://juser.fz-juelich.de/record/891688},
}