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Torikai, Y., Kikuchi, G., Owada, A., Masuzaki, S., Otsuka, T., Ashikawa, N., . . . JET Contributors, . (2024). Overview of tritium retention in divertor tiles and dust particles from the JET tokamak with the ITER-like wall. Nuclear Fusion, 64(1), Article ID 016032.
Open this publication in new window or tab >>Overview of tritium retention in divertor tiles and dust particles from the JET tokamak with the ITER-like wall
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2024 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 64, no 1, article id 016032Article in journal (Refereed) Published
Abstract [en]

Divertor tiles after Joint European Torus-ITER like wall (JET-ILW) campaigns and dust collected after JET-C and JET-ILW operation were examined by a set of complementary techniques (full combustion and radiography) to determine the total, specific and areal tritium activities, poloidal tritium distribution in the divertor and the presence of that isotope in individual dust particles. In the divertor tiles, the majority of tritium is detected in the surface region and, the areal activities in the ILW divertor are in the 0.5-12 kBq cm-2 range. The activity in the ILW dust is associated mainly with the presence of carbon particles being a legacy from the JET-C operation. The total tritium activities show significant differences between the JET operation with ILW and the earlier phase with the carbon wall (JET-C) indicating that tritium retention has been significantly decreased in the operation with ILW.

Place, publisher, year, edition, pages
IOP Publishing, 2024
Keywords
JET, ITER like wall, tritium, divertor, dust
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-340981 (URN)10.1088/1741-4326/ad0c08 (DOI)001113351800001 ()2-s2.0-85179883234 (Scopus ID)
Note

QC 20231218

Available from: 2023-12-18 Created: 2023-12-18 Last updated: 2024-01-02Bibliographically approved
Rubel, M., Primetzhofer, D., Petersson, P., Charisopoulos, S. & Widdowson, A. (2023). Accelerator techniques and nuclear data needs for ion beam analysis of wall materials in controlled fusion devices. EPJ TECHNIQUES AND INSTRUMENTATION, 10(1), Article ID 3.
Open this publication in new window or tab >>Accelerator techniques and nuclear data needs for ion beam analysis of wall materials in controlled fusion devices
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2023 (English)In: EPJ TECHNIQUES AND INSTRUMENTATION, ISSN 2195-7045, Vol. 10, no 1, article id 3Article, review/survey (Refereed) Published
Abstract [en]

A brief overview of ion beam analysis methods and procedures in studies of materials exposed to fusion plasmas in controlled fusion devices with magnetic confinement is presented. The role of accelerator techniques in the examination and testing of materials for fusion applications is emphasised. Quantitative results are based on robust nuclear data sets, i.e. stopping powers and reaction cross-sections. Therefore, the work has three major strands: (i) assessment of fuel inventory and modification of wall materials by erosion and deposition processes; (ii) equipment development to perform cutting-edge research; (iii) determination of nuclear data for selected ion-target combinations. Advantages and limitations of methods are addressed. A note is also given on research facilities with capabilities of handling radioactive and beryllium-contaminated materials.

Place, publisher, year, edition, pages
Springer Nature, 2023
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-325002 (URN)10.1140/epjti/s40485-023-00092-7 (DOI)000938927400001 ()
Note

QC 20230327

Available from: 2023-03-27 Created: 2023-03-27 Last updated: 2023-03-27Bibliographically approved
Zayachuk, Y., Jepu, I., Zlobinski, M., Porosnicu, C., Catarino, N., Pajuste, E., . . . Widdowson, A. (2023). Fuel desorption from JET-ILW materials: assessment of analytical approach and identification of sources of uncertainty and discrepancy. Nuclear Fusion, 63(9), 096010, Article ID 096010.
Open this publication in new window or tab >>Fuel desorption from JET-ILW materials: assessment of analytical approach and identification of sources of uncertainty and discrepancy
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2023 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 63, no 9, p. 096010-, article id 096010Article in journal (Refereed) Published
Abstract [en]

This work was carried out to identify sources of errors, uncertainties and discrepancies in studies of fuel retention in wall components from the JET tokamak using methods based on thermal desorption. Parallel aims were to establish good practices in measurements and to unify procedures in data handling. A comprehensive program designed for deuterium quantification comprised the definition and preparation of two types of materials (samples of JET limiter Be tiles and deuterium-containing targets produced in the laboratory by magnetron-assisted deposition), their pre-characterization, quantitative analyses of the desorption products in three different thermal desorption spectroscopy systems and a detailed critical comparison of the results. Tritium levels were also determined by several techniques in samples from JET and in tritiated targets manufactured specifically for this research program. Facilities available for studies of Be- and tritium-contaminated materials from JET are presented. Apparatus development, future research options and challenges are discussed.

Place, publisher, year, edition, pages
IOP Publishing, 2023
Keywords
fuel retention, thermal desorption, dissolution, JET-ILW
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-334754 (URN)10.1088/1741-4326/ace2d2 (DOI)001041325000001 ()2-s2.0-85166957472 (Scopus ID)
Note

QC 20230824

Available from: 2023-08-24 Created: 2023-08-24 Last updated: 2023-08-24Bibliographically approved
Dittrich, L., Petersson, P., Laabadi, H., Pitthan, E., Rubel, M., Widdowson, A., . . . Ciupiński, Ł. (2023). Impact of ion irradiation and film deposition on optical and fuel retention properties of Mo polycrystalline and single crystal mirrors. Nuclear Materials and Energy, 37, Article ID 101548.
Open this publication in new window or tab >>Impact of ion irradiation and film deposition on optical and fuel retention properties of Mo polycrystalline and single crystal mirrors
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2023 (English)In: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 37, article id 101548Article in journal (Refereed) Published
Abstract [en]

Polycrystalline (PC) and single crystal (SC) molybdenum mirrors were irradiated with 98Mo+, 1H+, 4He+, 11B+ and 184W+. Energies were chosen to impact the optically active region (up to 30 nm deep) of Mo mirrors. Some surfaces were coated by magnetron sputtering either with B or W films 4–65 nm thick. The overall objective was to simulate the neutron-induced damage and transmutation (H, He), and the impact of H, He, B, W on the optical performance of test mirrors, and on fuel retention. In parallel, a set of PC Mo mirrors irradiated with 1.6 MeV 98Mo3+ to a damage of 2 dpa and 20 dpa was installed in the JET tokamak for exposure during deuterium-tritium campaigns. Data from spectrophotometric, ion beam and microscopy techniques reveal: (i) the irradiation decreased specular reflectivity, whereby the differences between PC and SC in reflectivity are very small, (ii) He is retained in bubbles within 25–30 nm of the subsurface layer in all irradiated materials, (iii) W, either deposited or implanted, decreases reflectivity, but the strongest reflectivity degradation is caused by B deposition. Laboratory studies show the correlation of damage and H retention. Several cycles of W deposition and its removal from SC-Mo mirrors by plasma-assisted methods were also performed.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Boron, Diagnostic mirrors, Helium, Ion-induced damage, Molybdenum, Reflectivity
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-340976 (URN)10.1016/j.nme.2023.101548 (DOI)001125646100001 ()2-s2.0-85178075778 (Scopus ID)
Note

QC 20231218

Available from: 2023-12-18 Created: 2023-12-18 Last updated: 2024-01-10Bibliographically approved
Zayachuk, Y., Catarino, N., Smith, C., Jepu, I., Ayres, C., Widdowson, A., . . . Rubel, M. (2023). Impact of water ingress on deuterium release, oxidation, and dust generation in beryllium plasma-facing components. Nuclear Materials and Energy, 35, Article ID 101437.
Open this publication in new window or tab >>Impact of water ingress on deuterium release, oxidation, and dust generation in beryllium plasma-facing components
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2023 (English)In: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 35, article id 101437Article in journal (Refereed) Published
Abstract [en]

Beryllium samples from the JET ITER-like wall limiter tiles with either co-deposits or surface cracks caused by melt damage, were immersed into boiling water for 4 h 15 min to simulate and assess the impact of coolant water ingress into a tokamak on the state of Be components. Microscopy of the water-treated surfaces and the lack of residue in the water revealed that no thermomechanical damage (cracking or exfoliation) occurred to the samples during the exposure. Ion beam analysis showed no measurable release of deuterium from the samples. Combined ion beam analysis and Raman spectroscopy indicated only some degree of surface oxidation, but no thick oxide films were formed.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
IBA, JET-ILW, Oxidation, Raman spectroscopy, Thermomechanical damage, Water interaction
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-331593 (URN)10.1016/j.nme.2023.101437 (DOI)001042850000001 ()2-s2.0-85156235822 (Scopus ID)
Note

QC 20230712

Available from: 2023-07-12 Created: 2023-07-12 Last updated: 2023-08-24Bibliographically approved
Pitthan, E., Tran, T. T., Moldarev, D., Rubel, M. & Primetzhofer, D. (2023). Influence of thermal annealing and of the substrate on sputter-deposited thin films from EUROFER97 on tungsten. Nuclear Materials and Energy, 35, Article ID 101449.
Open this publication in new window or tab >>Influence of thermal annealing and of the substrate on sputter-deposited thin films from EUROFER97 on tungsten
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2023 (English)In: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 35, article id 101449Article in journal (Refereed) Published
Abstract [en]

The modification of sputter-deposited films from EUROFER97 on tungsten during and after annealing were investigated in-situ and ex-situ. The annealing resulted in a densification of the film, formation of large grains, segregation of W at the surface, and the formation of Fe-W compounds at the interfacial region. Similar structural modifications were observed also for a film annealed on a MgO substrate, with an exception to the change in composition (no increase of W concentration). Results indicate that the substrate significantly affects thermally induced modifications of re-deposited EUROFER97.

Place, publisher, year, edition, pages
Elsevier BV, 2023
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-331531 (URN)10.1016/j.nme.2023.101449 (DOI)001042748700001 ()2-s2.0-85160612576 (Scopus ID)
Note

QC 20230711

Available from: 2023-07-11 Created: 2023-07-11 Last updated: 2023-09-01Bibliographically approved
Dittrich, L., Petersson, P., Moon, S., Rubel, M., Tran, T. T., Widdowson, A. & Contribuors, J. E. (2023). Retention of noble and rare isotope gases in plasma-facing components-Experience from the JET tokamak with the ITER-like wall. Fusion engineering and design, 192, Article ID 113620.
Open this publication in new window or tab >>Retention of noble and rare isotope gases in plasma-facing components-Experience from the JET tokamak with the ITER-like wall
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2023 (English)In: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 192, article id 113620Article in journal (Refereed) Published
Abstract [en]

Plasma edge cooling, ion cyclotron wall conditioning and disruption mitigation techniques involve massive gas injection (by puffs or pellets) to the torus. A certain fraction remains in plasma-facing components (PFC) due to co-deposition and implantation. An uncontrolled release/desorption of such retained species affects the stability of plasma operation. The aim of this work was to determine the lateral and depth distribution of noble (3He, 4He, Ne, Ar), seeded (N2, Ne, Ar) and tracer gases (15N, 18O) in PFC retrieved from the JET tokamak with the ITER-Like Wall (JET-ILW) after three experimental campaigns (ILW-1, ILW-2, ILW-3). Results regarding the retention of those gases are shown as well as a comparison to the deuterium retention in the studied areas. Heavy ion elastic recoil detection analysis was used, being the only technique capable of detection and quantitative assessment of all elements, especially low-Z isotopes. Helium was found on the divertor Tile 5, locally up to 44.1015 3He cm-2 and 12.1015 4He cm-2, and on the limiters as well. Neon was found in two positions on the limiters, with up to 10.1015 Ne cm-2 and the 15N tracer on Be limiters exposed to ILW-3. A correlation of N retention with the N seeding rates for each campaign has also been found.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Plasma -wall interactions, Seeded gases, Plasma -facing materials, JET tokamak, ITER-like wall
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-326042 (URN)10.1016/j.fusengdes.2023.113620 (DOI)000956841500001 ()2-s2.0-85150767994 (Scopus ID)
Note

QC 20230424

Available from: 2023-04-24 Created: 2023-04-24 Last updated: 2023-04-24Bibliographically approved
Pitthan, E., Petersson, P., Tran, T. T., Moldarev, D., Kaur, R., Shams-Latifi, J., . . . Primetzhofer, D. (2023). Thin films sputter-deposited from EUROFER97 in argon and deuterium atmosphere: Material properties and deuterium retention. Nuclear Materials and Energy, 34, Article ID 101375.
Open this publication in new window or tab >>Thin films sputter-deposited from EUROFER97 in argon and deuterium atmosphere: Material properties and deuterium retention
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2023 (English)In: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 34, article id 101375Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Plasma facing components, EUROFER97, Sputtering deposition, Ion beam analysis, Deuterium retention
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-328283 (URN)10.1016/j.nme.2023.101375 (DOI)000990188500001 ()2-s2.0-85147198848 (Scopus ID)
Note

QC 20230607

Available from: 2023-06-07 Created: 2023-06-07 Last updated: 2023-06-07Bibliographically approved
Lee, S., Hatano, Y., Masuzaki, S., Oya, Y., Tokitani, M., Yajima, M., . . . Contributors, J. E. (2023). Tritium distributions in castellated structures of Be limiter tiles from JET-ITER-like wall experiments. Nuclear Fusion, 63(4), Article ID 046023.
Open this publication in new window or tab >>Tritium distributions in castellated structures of Be limiter tiles from JET-ITER-like wall experiments
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2023 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 63, no 4, article id 046023Article in journal (Refereed) Published
Abstract [en]

Tritium retention in the castellated structure of beryllium limiters used in JET with the ITER-like wall (ILW) during the first (ILW1), third (ILW3) and all three (ILW1-3) campaigns were examined and evaluated. Tritium was deposited on the surfaces inside the castellation grooves together with deuterium, beryllium, oxygen, carbon and small amounts of metallic impurities such as nickel, copper and tungsten. The tritium content after the ILW1 campaign was greater than after the ILW3 campaign. This is attributed to the steadily decreasing amount of carbon impurities in JET from campaign to campaign. The majority of tritium was retained in shallow regions in the grooves, up to 2 mm from the entrance to the gap. It was comparable on all sides of the castellation, i.e. no difference has been detected between the toroidal and poloidal gaps. Secondly, the tritium retention in the gaps was similar on all specimens independent of their position in the tokamak, while the retention on the plasma-facing surfaces clearly depended on the tile position. The tritium deposition patterns in the castellation were also compared with the deuterium distribution determined in earlier studies.

Place, publisher, year, edition, pages
IOP Publishing Ltd, 2023
Keywords
JET-ITER like wall, tritium retention, beryllium limiters, castellation, deposition in gaps
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-325195 (URN)10.1088/1741-4326/acb9a5 (DOI)000945758800001 ()2-s2.0-85150070440 (Scopus ID)
Note

QC 20230403

Available from: 2023-04-03 Created: 2023-04-03 Last updated: 2023-04-03Bibliographically approved
Weckmann, A., Petersson, P., Varju, J., Jerab, M., Horacek, J., Adamek, J., . . . Rubel, M. (2022). 3D deposition patterns of deuterium retention and impurities in the COMPASS divertor: a data-driven root cause analysis and prediction approach. Fusion engineering and design, 179, Article ID 113118.
Open this publication in new window or tab >>3D deposition patterns of deuterium retention and impurities in the COMPASS divertor: a data-driven root cause analysis and prediction approach
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2022 (English)In: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 179, article id 113118Article in journal (Refereed) Published
Abstract [en]

Divertor tiles from the COMPASS tokamak have been examined with ion beam analysis for the determination of deuterium retention and co-deposits. A novel approach was used to draw 2D deuterium retention maps at different depths and correlated to the concentrations of other elements: boron, carbon, oxygen and metals. This approach, which employs all three spatial dimensions, revealed that the deuterium retention pattern is not toroidally symmetric at different depths while the overall deuterium pattern is toroidally symmetric. Analysis of visible-light camera records disclosed that parts of the divertor were not wetted by plasma. The radial profile of deuterium in both wetted and non-wetted ( "shadowed ") divertor regions was compared to strike point positions, angle of incidence, electron temperature T-e, parallel heat flux Q(par) and ion saturation current Isat in order to find the influence of these parameters on deuterium retention. There are certain series of consecutive shots for which correlations between deuterium retention and separate plasma parameters (T-e, I-sat, Q(par)) are high. Combining the three parameters in a linear model or a power law model enabled reconstruction of the radial deuterium retention pattern. After fitting the model to one third of the data points, the deuterium retention for shadowed tiles was reproduced at the other two thirds of the data points within 20% deviation. This study shows the need for detailed tile analysis in three dimensions, the great benefits of broad statistical analysis in solving challenges in fusion, and motivates the investigation of COMPASS tiles after dismantling.

Place, publisher, year, edition, pages
Elsevier BV, 2022
Keywords
COMPASS, Deuterium retention, Co-deposited layers, Ion beam analysis, Data analysis
National Category
Energy Engineering Public Health, Global Health, Social Medicine and Epidemiology Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-314839 (URN)10.1016/j.fusengdes.2022.113118 (DOI)000806819400002 ()2-s2.0-85128237245 (Scopus ID)
Note

QC 20220627

Available from: 2022-06-27 Created: 2022-06-27 Last updated: 2022-06-27Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-9901-6296

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