| 1. |
- Pitthan, Eduardo, et al.
(författare)
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Thin films sputter-deposited from EUROFER97 in argon and deuterium atmosphere : Material properties and deuterium retention
- 2023
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Ingår i: Nuclear Materials and Energy. - : Elsevier. - 2352-1791. ; 34
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Tidskriftsartikel (refereegranskat)abstract
- Sputter-deposited thin films (33–1160 nm) from EUROFER97 were obtained on different substrates (C, Si, W, MgO) in argon and a mix of argon and deuterium atmosphere. The composition, microstructure, and mechanical properties of the films were analyzed and compared to those of the bulk material. The films feature lower density (-10%), higher hardness (+79%), and smaller crystallites in comparison to the bulk. Despite such differences, the elemental atomic composition of the films and the bulk was very similar, as determined by ion beam analysis. Deposition in deuterium-containing atmosphere resulted in a low deuterium incorporation (0.28% of atomic content), indicating low retention of hydrogen-isotopes in the deposited material.
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| 2. |
- Shams-Latifi, Jila, et al.
(författare)
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An in-situ ToF-LEIS and AES study of near-surface modifications of the composition of EUROFER97 induced by thermal annealing
- 2022
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Ingår i: Nuclear Materials and Energy. - : Elsevier. - 2352-1791. ; 30
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Tidskriftsartikel (refereegranskat)abstract
- Surface segregation and diffusion of W, Ta, Cr, O and S after thermal annealing of EUROFER97 were studied in-situ. The sample was prepared by polishing, annealing up to 300??& nbsp;and 3 keV Ar sputtering. In-situ measurements with time-of-flight low energy ion scattering using 8 keV Ne ions and Auger electron spectroscopy were carried out close to room temperature after each annealing, in sequence, to 425?, 675?, 400?, 675?, 900?, and 925?. Surface segregation/diffusion of chromium and tungsten and/or tantalum can be observed in the ion scattering spectra. The segregation of sulfur was clearly observed in Auger electron spectroscopy. The energy converted time-of-flight low-energy ion scattering spectrum after the first annealing to 675?& nbsp;was compared to Monte-Carlo simulations using the TRBS code. The most compatible simulation indicates a layer enriched in W + Ta of 1 +/- 0.3 nm featuring 0.0276 combined relative concentration of tungsten and tantalum to total metal content which is considerably higher than the bulk value of 0.0042.
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| 3. |
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| 4. |
- Shams-Latifi, Jila, et al.
(författare)
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Experimental electronic stopping cross-section of tungsten bulk and sputter-deposited thin films for slow protons, deuterons and helium ions
- 2023
-
Ingår i: Nuclear Materials and Energy. - : Elsevier BV. - 2352-1791. ; 36
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Tidskriftsartikel (refereegranskat)abstract
- The experimental electronic stopping cross-section of tungsten for low-energy protons, deuterons, and helium ions is deduced from backscattering experiments from thin films and bulk using time-of-flight low-energy ion scattering (ToF-LEIS). Two complementary experimental approaches showed consistent results in the energy ranges of 0.3-10 keV for protons, 0.33-10 keV for deuterons, and 0.7-10 keV for He+ ions. In relative mea-surements, a Au sample was used as the reference, while in absolute energy loss measurements, sputter-deposited thin films of tungsten on carbon substrates were employed. The experimental energy-converted spectra were compared to Monte-Carlo simulations in both approaches for quantitative analysis taking the influence of plural and multiple scattering into account. The results show proportionality to the ion velocity. We discuss the present datasets in comparison to semiempirical modelling and predictions from theory.
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| 5. |
- Shams-Latifi, Jila, 1992-
(författare)
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Interactions of low-energy ions with plasma-facing materials : Fundamental and applied aspects
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Materials in ultimate proximity of a burning plasma in controlled thermonuclear fusion devices, referred to as plasma-facing materials (PFMs), are exposed to a high flux of impinging particles and extreme conditions such as high thermal loads. In consequence, these materials are modified in manifold ways due to interactions with energetic plasma species. In this thesis, the potential of time-of-flight low-energy ion scattering (ToF-LEIS) for fundamental and applied studies relevant to improving our understanding of plasma-materials interactions was explored. ToF-LEIS is a non-destructive method to study the near-surface composition of materials providing high depth resolution and surface sensitivity. The investigated materials are tungsten and EUROFER97, both as bulks and in the form of different thin film stacks. W is proposed for the first wall of ITER, as well as for the divertor and coating for the first wall of DEMO. EUROFER97 is a reduced activation steel to be used as a structural material for the ITER test blanket and the first wall of DEMO's blanket.In the first part of this thesis, the potential of low-energy ions for quantitative composition depth profiling of near-surface modifications in PFMs induced by thermal loads was explored. Specifically, ToF-LEIS in combination with Auger electron spectroscopy was employed to study the influence of elevated temperatures on the near-surface composition of EUROFER97. The results demonstrated and quantified thermally induced segregation of W, Cr and S to the first nm of EUROFER97 under thermal loads. In the second part, this thesis focused on developing sample systems and measurement routines for assessing electronic interactions of low-energy ions with common PFMs. Developed samples were employed to experimentally deduce the electronic stopping power of W and EUROFER97 using ToF-LEIS and Monte-Carlo simulations for low-energy H, D and He ions, in the range of 0.3 – 10 keV for W and 3 – 10 keV for EUROFER97. Obtained comprehensive datasets represent the first experimental data of the electronic stopping power of W and EUROFER97 at low energies for the employed ions representing dominating plasma species. Results were compared to theoretical and semiempirical models and are essential inputs for modelling particle range or sputter yields.
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| 6. |
- Shams-Latifi, Jila, et al.
(författare)
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Sputter-deposition of ultra-thin film stacks from EUROFER97 and tungsten : characterisation and interaction with low-energy D and He ions
- 2024
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Ingår i: Materials Research Express. - : Institute of Physics (IOP). - 2053-1591. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- We have sputter-deposited stacks of ultrathin layers from EUROFER97 and tungsten on silicon substrates. Ion beam analysis techniques are used for composition characterisation and microscopy methods are employed for structural examination. The films are subsequently studied by time-of-flight low-energy ion scattering (ToF-LEIS) for primary 10 keV He+ and 8 keV D+ ions to demonstrate an approach of providing accurate and precise experimental reference electronic stopping cross-sections for fusion-relevant steels. The energy-converted ToF-LEIS spectra are compared to Monte-Carlo simulations for quantitative analysis explicitly considering the influence of plural and multiple scattering. We discuss the deduced stopping cross-sections of EUROFER97 in comparison to predictions by SRIM using Bragg's rule of stopping power additivity.
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