[en] The interaction between the plasma and the wall materials in a fusion reactor is the key factor in determining the useful life of the wall components. This interaction includes the erosion and redeposition of material in the plasma-facing wall, accompanied by the formation of alloys from the different materials present. These processes are critical for the retention of hydrogen isotopes by the wall materials. Determining the amount and the depth profile of Be and other elements is crucial for understanding those phenomena making the knowledge of its cross sections essential for ion beam analysis of these systems. The discrepancies and lack of knowledge on fundamental parameters required for ion beam techniques, raised the need to fill the gaps in the experimental data base of the nuclear differential cross-section reactions induced by ³He in ⁹Be. In this work we determined the ⁹ For ⁹Be(³He,pₓ)¹¹B (i = 0 − 9) cross-sections, obtained using a thin beryllium film target at the backscattering angles between 110◦ and 165◦ with a 5◦step and in the energy range between 1.0 and 2.5 MeV, which is the relevant energy range for the ion beam tchniques. The results were compared with the two previous studies in the same energy range. The results are in very good agreement with one of these studies and were benchmarked with the measurement of thick target reaction yields from a pure beryllium target at 2.0 MeV for 115◦ , 135◦ and 155◦. (author)

[en] Position-sensitive detectors (PSD) has proven to be a very important tool in recent years, especially in its applications in material sciences, astronomy, medical imaging, and high-energy physics, among others. In this work we present our st results on the use of two types of PSD's in the ld of materials science, particularly for lattice location studies using the RBS/Channeling technique in blocking geometry with a 0.5 mm collimated 2.0 MeV alpha-particle beam from a Van de Graa accelerator. Also, some key features such as the maximum count rate, and both energy and position resolution of these detectors will be reported. Firstly, a resistive-charge position sensitive detector was used to carry out lattice location studies in Si C:Fe, Al N:E r and Si:Ir implanted samples. The channeling and 2D blocking patterns were detected by means of measuring the angular distribution of scattered alpha particles around major crystallographic axes and planes using this type of detector. Furthermore, both the minimum yield and amorphous fraction of single-crystal samples were determined by ting the normalized 2D patterns with Monte Carlo simulations. Currently, ongoing experiments are carried out in order to assess the suitability of a hybrid semiconductor pixel detector (Time pix) operated in the Time-over-Threshold mode (To T) for lattice location and damage annealing studies in SrTiO3 substrates. So far, RBS/Channeling experiments performed in several single-crystal samples are showing that this type of detectors seem suitable for lattice location studies, particularly for heavy ion implantation (D ≥1015 at/c m2) on light substrates. Additionally, after several experiments under ion beam conditions the performance of each detector does not show any noticeable deterioration due to radiation damage

[en] The micro-probe facility installed at the Van de Graff accelerator at CTN/IST permits simultaneous measurements of Rutherford Backscattering Spectrometry (RBS), Particle Induced X-ray Emission (PIXE) and Iono-Luminescence (IL). Here we present a recent up-grade of the measurement chamber allowing improved optical sensitivity in IL measurements and opening the possibility to perform simultaneously electrical measurements. Combinations of all these characterization techniques make this setup a powerful tool to characterize and modify different materials with spatial resolution. In particular, it can be used to study radiation effects in different materials and electronic devices in-situ. IL is a luminescence technique that uses the ion beam as the excitation source. Compared with other luminescence techniques with spatial resolution like Cathodoluminescence, this technique has the advantage to probe deeper regions of the sample, several microns below the surface. The same ion beam used to produce luminescence, can create a high density of defects, in a controllable way and the new set-up allows monitoring optical and electrical properties in realtime. In this work we combine IL with I-V curve measurements to assess the response of Ga_2O_3 and GaN to proton irradiation. Ga_2O_3 and GaN are emerging materials for applications in high power electronics and are considered for radiation resistant electronics. We will present a systematic study of the changes in IL and conductivity in Ga_2O_3 and GaN samples with the energy of the ion beam and with the time of exposure. In particular, it was observed that during the irradiation some luminescence bands related with intrinsic point defects decrease while other new bands appear. Simulations using the SRIM code were used to determine the depth profiles of ionization and displacement events, helping to correlate the optical and electrical response of the materials with certain radiation effects. These studies show the potentialities of measuring simultaneously IL and electrical conductivity and how these two characterization techniques can work as a sensitive tool to detect and quantify radiation effects. (authors)

[en] The potential of Gold nanoparticles (NPs) as biosensors is being widely explored in several fields like biology, medicine, chemistry and physics. The applications in chemical and bio- sensing, phototherapy of tumours, nanoscopy and optical imaging are among the most relevant. In this work, we use ion implantation technology to produce Au-nanoparticles in TiO₂ dielectric layers in a controlled way. Ion implantation is ideal to control size and depth distribution of the nanoparticles. Titanium Dioxide films with different thicknesses were deposited by direct current magnetron sputtering method on silicon and glass (for optical studies) substrates. The Au ions with multiple energies were implanted with different fluences to produce a box like profile. The energies used were 50 keV and 150 keV with fluences in the range 1 × 10¹⁶ to 2 × 10¹⁷ ions/cm² . After implantation the samples were submitted to annealing in air at 500°C for 15 min to induce the precipitation of the Au ions.

[en] Beryllium and Tungsten have been chosen as the new “plasma facing materials” for fusion reactors. Understanding plasma wall interactions and their effects such as erosion and redeposition leading to the formation of alloys from the different materials present in the reactor chamber, is critical to model the retention of hydrogen isotopes by the wall materials. Determining the amount and the depth profile of Be and other elements deposited in the walls is a mandatory requirement in fusion reactors, making the knowledge of the relevant cross sections essential for IBA analysis. In this work we measured the "9Be(p,p_0)"9Be, "9Be(p,d_0)"8Be and "9Be(p,α_0)"6Li cross sections in the energy range 0.5–2.35 MeV, at an angle of 150°.

[en] The plasma-facing materials in the ITER divertor area must withstand unusual events, such as the edge-localized modes (ELMS). At the point when an ELM occurs, up to 30% of the energy can be deposited on the plasma-facing boundary in the form of the heat and particle load causing material loss due to sublimation. Tungsten is a promising candidate as a plasma-facing material in the ITER divertor area since it has a high melting point, good thermal conductivity and low sputtering yield, which minimizes the plasma contamination. However their brittleness at low temperatures which is worsened by irradiation is an issue. One strategy to modulate the properties of tungsten is alloying this element with other refractory metals, such as tantalum that shows higher toughness, lower activation and higher radiation resistance. In the present study tungsten-tantalum alloys (W-Ta) were produced by Ta implantation. The fundamental mechanisms which govern the behaviour of defect dynamics in W-Ta materials under reactor conditions, were simulated by the implantation of He and D. The microstructure observations of the W plates that after single Ta implantation revealed crater-like cavities and a more severe effect after D implantation. The effect increase with the increasing of D fluence. However at fluences higher than 10²¹D/m the effect is reduced. In addition, blistering was observed in W-Ta plates implanted with He. The D retention in the W-Ta alloys increases with the implanted fluence with tendency for saturation for high fluences. Moreover the results show that D retention is higher after sequential He and D implantation than for single D implantation. The diffractogram of W-Ta alloys implanted with He evidenced the presence of broadened W peaks associated with stress induced by irradiation, which may cause internal stress field resulting in a distortion of the crystal lattice. These irradiation defects can be observed in the D release spectra where three peaks are associated with three types of defects in W and W-Ta implanted with He and D.

[en] A build-up of co-deposits in remote areas of the divertor can contribute significantly to the overall fuel retention. The control of plasma-material interactions via the study and understanding of erosion-deposition of PFCs provides vital information for the efficient future operation of ITER. The major aim of this work is to reveal details of beryllium deposition and fuel (deuterium) retention on divertor plasma-facing componentsremoved from the JET ITER-Like Wall divertor after cumulative exposure during the first two (ILW−1 + 2) and all three (ILW−1 + 2 + 3) campaigns. Ion beam analysis techniques such as Rutherford backscattering spectrometry, nuclear reaction analysis and proton induced x-ray emission have been extensively used for post-mortem analyses of selected tiles from JET following each campaign and can provide relevant information on plasma-surface interactions like tungsten erosion, beryllium deposition and plasma fuel retention with divertor tiles via implantation or co-deposition. The studied divertor tiles represent a unique set of samples, which have been exposed to plasmas since the beginning of the JET-ILW operation for three successive plasma campaigns. This is a comprehensive comparison of divertor components after these operation periods. The results presented summarise deposition and fuel retention on Tiles 4 (inner base) and 6 (outer base). Although the deposition pattern is similar to that determined after individual campaigns, D retention is not a cumulative process and is determined mainly by the last campaign, and the total Be deposit after the 3 campaigns (i.e. data 1 + 2 + 3 = tile exposed 2011–2016) is less than the sum of the deposits after each individual campaign (sum 1 + 2 + 3) for Tile 4 but greater for Tile 6. (topical issue article)

[en] Highlights: • We measured the ^13C(p,p)¹³C cross section at 140° and 160° between 0.8 and 2.4 MeV. • The new data were used to evaluate the cross section using nuclear models. • The evaluated cross section was benchmarked around the 1.462 MeV resonance. • The cross section determined can be used for EBS measurements of ¹³C. -- Abstract: We used a thin film method with Bayesian inference data analysis to determine the ¹³C(p,p)¹³C cross section in the energy range 0.8–2.43 MeV, at scattering angles 140° and 160°. The accuracy of the results was also determined, including all sources of error. The cross section determined at 140° was benchmarked at energies around the 1.462 MeV resonance. The new data presented were then used, together with previously existing data from the literature, to perform an evaluation of the ¹³C(p,p)¹³C cross section

[en] Since August 2011 the JET tokamak has been operated with the ITER-Like Wall (JET-ILW): beryllium (Be) in the main chamber and tungsten (W) in the divertor. i.e. the material configuration recently decided for ITER. Material erosion and fuel inventory studies are among top priorities of the JET-ILW programme. Various types of diagnostic tools, i.e. marker tiles and wall probes including test mirrors, have been employed to assess the overall material migration pattern. The specific goals of this work were to determine: (i) fuel retention in the divertor; (ii) erosion-deposition pattern of beryllium and other species; (iii) the reflectivity and surface morphology of mirrors studied within the First Mirror Test at JET for ITER. Analyses of in-vessel components have shown the erosion of Be inner wall limiters and the deposition of material on the upper tiles in the inner divertor leg. The thickest deposits, up to 15 m, contain mainly beryllium with some minority species: carbon and also nitrogen from edge cooling. Their content is low: Be/C concentration ratio >16; Be/N >45. Also fuel inventory in JET-ILW is small, both relative: Be/D >10 in deposits and absolute being below 5x10¹⁸ cm^-2. This value is distinctly lower than in JET with carbon walls (JET-C) where layers of a few hundreds of micrometers were formed. The study has not identified on wall components the formation of flaking deposits which could contribute to the dust formation. It should also be stressed that the reflectivity of polycrystalline molybdenum mirrors tested on the main chamber wall was retained or even improved in some cases. This result may have a positive impact (e.g. cost reduction) on the planning and development of maintenance procedures for ITER diagnostic mirrors. The options will be presented. These findings indicate advantages of metal components in comparison to the carbon surrounding. (author)

[en] Ar ion implanted GaN and ZnO are studied at 295 K by Rutherford backscattering spectrometry in channelling configuration. Under these conditions in both materials damage formation proceeds in four steps which are characterised by the accumulation of point defects (I), a first saturation of the relative damage concentration at a value well below 10% (II), a second increase of the damage concentration (III) and a second plateau at about 60% for GaN and 40% for ZnO (IV). The results obtained here are compared to those reported previously for Ar ion implantation into these materials performed at 15 K. The main result of our studies is that damage formation is nearly the same for implantation at 295 K and 15 K. This suggests that thermally enhanced defect diffusion is not the main driving force during ion implantation of these materials. The shape of the channelling spectra observed in stages III and IV suggests the existence of both a high concentration of defect clusters and extended defects. The latter are proven to exist after implantation at 295 K. Therefore, there are arguments to conclude that extended defects form already during implantation at 15 K