This title appears in the Scientific Report :
2021
Stability of deuterated beryllium layers on tungsten substrates during transient heat loads by laser irradiation
Stability of deuterated beryllium layers on tungsten substrates during transient heat loads by laser irradiation
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. Matv...
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Personal Name(s): | Unterberg, B. (Corresponding author) |
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Zlobinski, Miroslaw / De Temmerman, G. / Porosnicu, C. / Matveev, D. / Sergienko, G. / Brezinsek, S. / Nicolai, D. / Rasinski, M. / Spilker, B. / Freisinger, M. / Möller, S. / Linsmeier, Ch. / Lungu, C. P. / Dinca, P. | |
Contributing Institute: |
Werkstoffsynthese und Herstellungsverfahren; IEK-1 Plasmaphysik; IEK-4 |
Imprint: |
2021
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Conference: | 24th International Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI 2020), virtuell (virtuell), 2021-01-25 - 2021-01-29 |
Document Type: |
Abstract |
Research Program: |
Plasma-Wand-Wechselwirkung |
Publikationsportal JuSER |
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 |