[en] With construction of ITER progressing and existing tokamaks carrying-out ITER-relevant experiments, accurate fundamental and derived atomic data for numerous ionization stages of tungsten (W) is required to assess the potential effect of this species upon fusion plasmas. The results of fully relativistic, partially radiation damped, Dirac R-matrix electron-impact excitation calculations for the ${\mathrm{W}}^{44+}$ ion are presented. These calculations use a configuration interaction and close-coupling expansion that opens-up the 3d-subshell; this does not appear to have been considered before in a collision calculation. As a result, it is possible to investigate the arrays, [3d¹⁰4s²–3d⁹4s²4f] and [3d¹⁰4s²–3d⁹4s4p4d], which are predicted to contain transitions of diagnostic importance for the soft x-ray region. Our R-matrix collision data are compared with previous R-matrix results by Ballance and Griffin as well as our own relativistically corrected, Breit–Pauli distorted wave and plane-wave Born calculations. All relevant data are applied to the collisional-radiative modelling of atomic populations, for further comparison. This reveals the paramount nature of the 3d-subshell transitions from the perspectives of radiated power loss and detailed spectroscopy. (paper)

[en] Total radiated line power coefficients for ions of medium to heavy weight elements, called $\mathcal{P}\mathcal{L}\mathcal{T}$ coefficients in the atomic data and analysis structure, have been improved by algorithmically optimising the selection of configuration sets that underpin the calculation to include the most important radiating transitions driven by both the ground and metastable configurations and to establish and limit the error of truncation. The optimised calculations typically differ from Pütterich by 20%–30% with truncation error $\lesssim <!--\; ???\; -->5\mathrm{\%<!--\; \%\; -->}$. Further appraisal of error due to atomic level bundling, atomic structure and collision strength calculation methods has been carried out. It is shown that bundling to configurations is accurate to $\lesssim <!--\; ???\; -->10\mathrm{\%<!--\; \%\; -->}$ for all ions except those with closed-shell ground configurations which give errors up to a factor 2–3. For near neutral, closed-shell ions, plane-wave Born collision strength calculations, which omit spin-change, give substantial error in comparison with distorted-wave calculations of $\mathcal{P}\mathcal{L}\mathcal{T}$. For highly charged ions, spin-system breakdown reduces the error in the $\mathcal{P}\mathcal{L}\mathcal{T}$ markedly, typically $\lesssim <!--\; ???\; -->10\mathrm{\%<!--\; \%\; -->}$. The error introduced by the atomic structure codes used here, autostructure and the Cowan code, is probably limited to $\lesssim <!--\; ???\; -->30\mathrm{\%<!--\; \%\; -->}$. (paper)

[en] Si nanocrystals have been prepared by hydrogenation and subsequent annealing of as-deposited amorphous Si layers on glass and Si substrates. The hydrogenation process has been performed at 350 °C under radio frequency hydrogen plasma. The nanocrystallites were processed by sequential reactive ion etching to allow light emission. Photoluminescence (PL) measurements demonstrate that the nanocrystallites emit light in the range of 500–570 nm. The evolution of nanocrystals has been studied using scanning electron microscopy, while atomic force microscopy and transmission electron microscopy have been utilized to examine the structure of the Si nanocrystals. Multilayer luminescent Si nanocrystals have been fabricated using alternating layers of Si nanocrystals and Si oxy-nitride. Bilayer structures have higher efficiency than a single layer structure, while multilayers with three layers of luminescent nanocrystals and above did not show a higher PL intensity. Transparent light emitting diodes have been realized based on multilayer luminescent Si nanocrystals that displayed bright emission which was visible to the naked eye in a bright room. - Highlights: ► Transparent light-emitting diodes using nano-porous silicon multilayers. ► Nano-porous silicon-based light-emitting diodes on glass substrates.

[en] The prediction of the first wall deterioration and possible plasma contamination by impurities is a high priority task for ITER. 3D Monte-Carlo code ERO is a tool for modeling of eroded impurity transport and spectroscopy in plasma devices useful for experiment interpretation. Chromium (Cr) is a fusion-relevant reactor wall element (e.g. component of RAFM steels expected for use in DEMO). Linear plasma devices including PSI-2 are effective tools for investigations of plasma-surface interaction effects, allowing continuous plasma operation and good control over irradiation parameters. Experiments on Cr sputtering were conducted at PSI-2. In these experiments the Cr erosion was measured by three techniques: mass loss of the sample, quartz micro-balance of deposited impurities at a distance from it and optical emission spectroscopy. Experiments were modeled with the 3D Monte-Carlo code ERO, previously validated by application to similar experiments with tungsten (W). The simulations are demonstrated to reproduce the main experimental outcomes proving the quality of the sputtering data used. A significant focuses of the paper is the usage and validation of atomic data (resent metastable-resolved dataset from ADAS) for interpretation of Cr spectroscopy. Initial population of quasi-metastable state was fitted by matching the modeling with the experimental line intensity profiles. (paper)