Abstract. Polycrystalline, annealed tungsten targets were bombarded with 12.3 MeV W 4+ ions to various damage levels. Deuterium was implanted by high-flux plasmas in Pilot-PSI ( >10 24 m -2 s -1 ) at a surface temperature below 525 K. Deuterium retention has been studied by Nuclear Reaction Analysis and by Thermal Desorption Spectroscopy. We found that deuterium retention is strongly enhanced by the tungsten bombardment and that saturation occurs at a W 4+ fluence of about 3·10 17 m -2 . The maximum deuterium concentration in the damaged region was measured to be 1.4 at.%. This is in accordance with other experiments that were carried out at much lower fluxes. We therefore conclude that the saturation behaviour and the maximum retention are not affected by the high fluxes used in our experiments.A simple geometric model is presented that assumes that the saturation solely originates in the tungsten irradiation and that explains it in terms of overlapping saturated volumes. The saturated volume per incident MeV ion amounts to 3·10 4 nm 3 . From our results, we are able to obtain an approximate value for the average occupation number of the vacancies.

Surface and sub-surface morphology and deuterium retention in polycrystalline tungsten, undamaged and pre-damaged with 5. The dependence of the D retention on the damage level and the implanted fluence was studied, and the results show saturation for 0.4 dpa independent of the deuterium implantation fluence. Additionally, it was observed that self-implantation introduces high temperature traps which can almost completely be removed by annealing at 1200 K.

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Two sets of identical tungsten (W) targets are irradiated at 300 K with 12.3 MeV W 4+ ions to peak damage levels ranging from 0.5-10 displacements per atom (dpa). This results in a damage profile that is peaked at ~0.8 µm and extends to a depth of ~1.5 µm. Both sets of targets are exposed to high-density (n e,center = 3 x 10 20 m -3 ), lowtemperature (T e,center = 1.6 eV) deuterium (D) plasma in Pilot-PSI. One set of irradiated targets is exposed at high surface temperatures (T W = 950 -680 K) and the other at low surface temperatures (T W = 480 K -340 K). The surface temperature is determined by the local plasma conditions. Nuclear reaction analysis (NRA) is used to determine the D depth profiles at specific radial locations, thus giving a surface temperature scan of the D retention in the damaged W. Global retention is determined by thermal desorption spectroscopy, which yields total D retained in the target and also gives information of the different types of lattice defects that are trapping the D in the W lattice. The main results are that there is no measurable difference between the different dpa levels, implying a saturation of the retention enhancement at a level ≤0.5 dpa. For both irradiated and unirradiated tungsten, a peak in the retention is seen at T W = 480 K, however the W 4+ irradiation clearly enhances the retention. This enhancement is also temperature dependent and increases with increasing surface temperature up to an enhancement by a factor of 15-23 at T W = 950 K. At the lowest surface temperatures, a fluence dependence appears since the implanted deuterium is diffusion limited to only a small fraction of the irradiated zone. TDS spectra show an enhancement of both low energy trap sites and high energy trap sites. For these conditions, diffusion-limited, low fill fraction trapping determines the hydrogenic retention of the W.

The reconstruction of 2-D emissivity profiles from soft X ray tomography measurements constitutes a highly underdetermined and ill-posed inversion problem, because of the restricted viewing access, the number of chords and the increased noise level in most plasma devices. An unbiased and consistent probabilistic approach within the framework of Bayesian inference is provided by the maximum entropy method, which is independent of model assumptions, but allows any prior knowledge available to be incorporated. The formalism is applied to the reconstruction of emissivity profiles in an NBI heated plasma discharge to determine the dependence of the Shafranov shift on p, the reduction of which was a particular objective in designing the advanced W7-AS stellarator.

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Heavy ion irradiation induced dislocation loops in AREVA's M5 alloy Cover letter for the second revised submission of the article to the Journal of Nuclear MaterialsPressurized water reactor (PWR) Zr-based alloy structural materials show creep and growth under neutron irradiation as a consequence of the irradiation induced microstructural changes in the alloy. A better scientific understanding of these microstructural processes can improve simulation programs for structural component deformation and simplify the development of advanced deformation resistant alloys. As in-pile irradiation leads to high material activation and requires long irradiation times, the objective of this work was to study whether ion irradiation is an applicable method to simulate typical PWR neutron damage in Zr-based alloys, with AREVA's M5 ® alloy as reference material. The irradiated specimens were studied by electron backscatter diffraction (EBSD), positron Doppler broadening spectroscopy (DBS) and in-situ transmission electron microscopy (TEM) at different dose levels and temperatures. The irradiation induced microstructure consisted of -and -type dislocation loops with their characteristics corresponding to typical neutron damage in Zr-based alloys; it can thus be concluded that heavy ion irradiation under the chosen conditions is an excellent method to simulate PWR neutron damage.As recommended by the editor, the abstract has been shortened. Heavy ion irradiation induced dislocation loops in AREVA's M5 alloy Detailed Response to the reviewersThe authors want to thank the reviewers for their helpful and detailed comments.The following changes have been made in the revised article, based on the reviewers' suggestions:General Changes: The units for flux and fluence have been converted from cm^-2 to m^-2. Reviewer 1: The labelling of the sections and subsections in the text has been corrected.  While a difference in positron lifetime measurements between single vacancies and vacancy clusters can be resolves with positron lifetime measurements, it is more difficult to decide whether the difference would be reflected in the Doppler broadening spectroscopy signal. Therefore, all passages implicating such a correlation have been removed or reworded, as recommended by the reviewer.  The reference for 0.3wt.% of Nb in solution has been added.  The references have been re-ordered to appear in the right order.  A schematic of the EBSD specimen cutting process has not been included; however, the specimen preparation description has been revised to make it more comprehensible.  The typing error of 6450°C annealing temperature has been corrected.  The diffraction vector for the -loop observation was (11-20) and not (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) as was incorrectly stated in the draft; the error has been corrected.  The interpretation of the additional reflexes in sample A1 after irradiation has been reworded. A more detailed explanation is given why oxidation is not assumed to be the cause of the changes.  A ...

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