Browsing by Subject "Beryllium"

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  • Byggmästar, Jesper; Hodille, Etienne A.; Ferro, Y.; Nordlund, Kai (2018)
    An analytical interatomic bond order potential for the Be–O system is presented. The potential is fitted and compared to a large database of bulk BeO and point defect properties obtained using density functional theory. Its main applications include simulations of plasma-surface interactions involving oxygen or oxide layers on beryllium, as well as simulations of BeO nanotubes and nanosheets. We apply the potential in a study of oxygen irradiation of Be surfaces, and observe the early stages of an oxide layer forming on the Be surface. Predicted thermal and elastic properties of BeO nanotubes and nanosheets are simulated and compared with published ab initio data.
  • Gonsalves, Basil C.; Mizohata, Kenichiro; Tikkanen, Pertti O.; Räisänen, Jyrki A. (2020)
    The yields of Be-9 charge states (q = +1, + 2, +3, and + 4) from injected BeO- were measured with terminal voltage range from 1 to 5 MV. The yields were determined from the momentum analysed beam currents measured by beam profile monitors, after the 90 degrees injector and analysing magnets. Stripping gas pressure dependency of the transmission efficiency was also determined and the results were studied with SRIM simulations. The effect of stripping medium was studied using both Ar and CO2 gases. The presented results are compared against experimental values found from literature, semi-empirical parametrisation models, and charge-exchange theories.
  • De Temmerman, Gregory; Heinola, Kalle; Borodin, Dmitriy; Brezinsek, Sebastijan; Doerner, Russell P.; Rubel, Marek; Fortuna-Zalesna, Elzbieta; Linsmeier, Christian; Nishijima, Daisuke; Nordlund, Kai; Probst, Michael; Romazanov, Juri; Safi, Elnaz; Schwarz-Selinger, Thomas; Widdowson, Anna; Braams, Bastiaan J.; Chung, Hyun-Kyung; Hill, Christian (2021)
    ITER will use beryllium as a plasma-facing material in the main chamber, covering a total surface area of about 620 m(2). Given the importance of beryllium erosion and co-deposition for tritium retention in ITER, significant efforts have been made to understand the behaviour of beryllium under fusion-relevant conditions with high particle and heat loads. This paper provides a comprehensive report on the state of knowledge of beryllium behaviour under fusion-relevant conditions: the erosion mechanisms and their consequences, beryllium migration in JET, fuel retention and dust generation. The paper reviews basic laboratory studies, advanced computer simulations and experience from laboratory plasma experiments in linear simulators of plasma-wall interactions and in controlled fusion devices using beryllium plasma-facing components. A critical assessment of analytical methods and simulation codes used in beryllium studies is given. The overall objective is to review the existing set of data with a broad literature survey and to identify gaps and research needs to broaden the database for ITER.
  • Meluzova, D. S.; Babenko, P. Yu.; Shergin, A. P.; Nordlund, K.; Zinoviev, A. N. (2019)
    Particle reflection coefficients for scattering of hydrogen and deuterium atoms from amorphous beryllium, carbon and tungsten were obtained, which are of interest for thermonuclear reactor physics. For the case of deuterium scattering from tungsten the data were also calculated for polycrystalline and crystalline target. The calculations were carried out by two methods: by modeling the trajectories of the incident particles and by using the binary collision approximation. Interaction potentials between hydrogen and helium atoms and the selected materials were calculated in the scope of the density function theory using program DMol for choosing wave functions. The dependence of the reflection coefficient RN on the potential well depth was found. The results demonstrate a good agreement with the available experimental values.
  • Baron-Wiechec, A.; Heinola, K.; Likonen, J.; Alves, E.; Catarino, N.; Coad, J. P.; Corregidor, V.; Jepu, I.; Matthews, G. F.; Widdowson, A.; JET Contributors (2018)
    The phenomena of retention and de-trapping of deuterium (D) and tritium (T) in plasma facing components (PFC) and supporting structures must be understood in order to limit or control total T inventory in larger future fusion devices such as ITER, DEMO and commercial machines. The goal of this paper is to present details of the thermal desorption spectrometry (TDS) system applied in total fuel retention assessment of PFC at the Joint European Torus (JET). Examples of TDS results from beryllium (Be) wall tile samples exposed to JET plasma in PFC configuration mirroring the planned ITER PFC is shown for the first time. The method for quantifying D by comparison of results from a sample of known D content was confirmed acceptable. The D inventory calculations obtained from Ion Beam Analysis (IBA) and TDS agree well within an error associated with the extrapolation from very few data points to a large surface area.