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Oya, Y., Masuzaki, S., Tokitani, M., Azuma, K., Oyaidzu, M., Isobe, K., . . . Contributors, J. (2018). Correlation of surface chemical states with hydrogen isotope retention in divertor tiles of JET with ITER-Like Wall. Fusion engineering and design, 132, 24-28
Open this publication in new window or tab >>Correlation of surface chemical states with hydrogen isotope retention in divertor tiles of JET with ITER-Like Wall
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2018 (English)In: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 132, p. 24-28Article in journal (Refereed) Published
Abstract [en]

To understand the fuel retention mechanism correlation of surface chemical states and hydrogen isotope retention behavior determined by XPS (X-ray photoelectron spectroscopy) and TDS (Thermal desorption spectroscopy), respectively, for JET ITER-Like Wall samples from operational period 2011–2012 were investigated. It was found that the deposition layer was formed on the upper part of the inner vertical divertor area. At the inner plasma strike point region, the original surface materials, W or Mo, were found, indicating to an erosion-dominated region, but deposition of impurities was also found. Higher heat load would induce the formation of metal carbide. At the outer horizontal divertor tile, mixed material layer was formed with iron as an impurity. TDS showed the H and D desorption behavior and the major D desorption temperature for the upper part of the inner vertical tile was located at 370 °C and 530 °C. At the strike point region, the D desorption temperature was clearly shifted toward higher release temperatures, indicating the stabilization of D trapping by higher heat load.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Hydrogen isotope behavior, JET-ILW, Plasma wall interactions
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-228730 (URN)10.1016/j.fusengdes.2018.04.124 (DOI)000436887700005 ()2-s2.0-85046629650 (Scopus ID)
Funder
EU, European Research Council
Note

QC 20180529

Available from: 2018-05-29 Created: 2018-05-29 Last updated: 2018-07-17Bibliographically approved
Rubel, M., Widdowson, A., Grzonka, J., Fortuna-Zalesna, E., Moon, S., Petersson, P., . . . Tokitani, M. (2018). Dust generation in tokamaks: Overview of beryllium and tungsten dust characterisation in JET with the ITER-like wall. Paper presented at 13th International Symposium on Fusion Nuclear Technology (ISFNT), SEP 25-29, 2017, Kyoto, Japan. Fusion engineering and design, 136, 579-586
Open this publication in new window or tab >>Dust generation in tokamaks: Overview of beryllium and tungsten dust characterisation in JET with the ITER-like wall
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2018 (English)In: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 136, p. 579-586Article in journal (Refereed) Published
Abstract [en]

Operation of the JET tokamak with beryllium and tungsten ITER-like wall provides unique opportunity for detailed studies on dust generation: quantity, morphology, location, etc. The programme carried out in response to ITER needs for safety assessment comprises: (i) remotely controlled vacuum cleaning of the divertor; (ii) local sampling of loosely bound matter from plasma-facing components (PFC); (iii) collection of mobilized dust on various erosion-deposition probes located in the divertor and in the main chamber. Results of comprehensive analyses performed by a number of complementary techniques, e.g. a range of microscopy methods, electron and ion spectroscopy, liquid scintillography and thermal desorption, are summarized by following points: (a) Total amount of dust collected by vacuum cleaning after three campaigns is about 1-1.4 g per campaign (19.1-23.5 h plasma operation), i.e. over 100 times smaller than in JET operated with carbon walls (i.e. in JET-C). (b) Two major categories of Be dust are identified: flakes of co-deposits formed on PFC and droplets (2-10 mu m in diameter). Small quantifies, below 1 g, of Be droplets and splashes are associated mainly with melting of beryllium limiters.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
JET tokamak, ITER-like wall, Dust, Beryllium, Tungsten
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-240780 (URN)10.1016/j.fusengdes.2018.03.027 (DOI)000452583700110 ()2-s2.0-85044008512 (Scopus ID)
Conference
13th International Symposium on Fusion Nuclear Technology (ISFNT), SEP 25-29, 2017, Kyoto, Japan
Note

QC 20190109

Available from: 2019-01-09 Created: 2019-01-09 Last updated: 2019-01-09Bibliographically approved
Ström, P., Petersson, P., Rubel, M. & Possnert, G. (2018). Erratum: "A combined segmented anode gas ionization chamber and time-of-flight detector for heavy ion elastic recoil detection analysis" [Rev. Sci. Instrum. 87, 103303 (2016)]. Review of Scientific Instruments, 89(4), Article ID 049901.
Open this publication in new window or tab >>Erratum: "A combined segmented anode gas ionization chamber and time-of-flight detector for heavy ion elastic recoil detection analysis" [Rev. Sci. Instrum. 87, 103303 (2016)]
2018 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 89, no 4, article id 049901Article in journal (Refereed) Published
Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2018
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-227781 (URN)10.1063/1.5030502 (DOI)000431139400078 ()29716341 (PubMedID)2-s2.0-85045335587 (Scopus ID)
Note

QC 201805014

Available from: 2018-05-14 Created: 2018-05-14 Last updated: 2019-01-09Bibliographically approved
Fazinic, S., Tadic, T., Vuksic, M., Rubel, M., Petersson, P., Fortuna-Zalesna, E. & Widdowson, A. (2018). Ion Microbeam Analyses of Dust Particles and Codeposits from JET with the ITER-Like Wall. Analytical Chemistry, 90(9), 5744-5752
Open this publication in new window or tab >>Ion Microbeam Analyses of Dust Particles and Codeposits from JET with the ITER-Like Wall
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2018 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 90, no 9, p. 5744-5752Article in journal (Refereed) Published
Abstract [en]

Generation of metal dust in the JET tokamak with the ITER-like wall (ILW) is a topic of vital interest to next-step fusion devices because of safety issues with plasma operation. Simultaneous Nuclear Reaction Analysis (NRA) and Particle Induced X-ray Emission (PIXE) with a focused four MeV He-3 microbeam was used to determine the composition of dust particles related to the JET operation with the ILW. The focus was on "Be-rich particles" collected from the deposition zone on the inner divertor tile. The particles found are composed of a mix of codeposited species up to 120 m in size with a thickness of 30-40 mu m, The main constituents are D from the fusion fuel, Be and W from the main plasma-facing components, and Ni and Cr from the Inconel grills of the antennas for auxiliary plasma heating. Elemental concentrations were estimated by iterative NRA-PIXE analysis. Two types of dust particles were found: (i) larger Be-rich particles with Be concentrations above 90 at% with a deuterium presence of up to 3.4 at% and containing Ni (1-3 at%), Cr (0.4-0.8 at%), W (0.2-0.9 at%), Fe (0.3-0.6 at%), and Cu and Ti in lower concentrations and (ii) small particles rich in Al and/or Si that were in some cases accompanied by other elements, such as Fe, Cu, or Ti or W and Mo.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-228440 (URN)10.1021/acs.analchem.8b00073 (DOI)000431464400032 ()29620878 (PubMedID)2-s2.0-85046455477 (Scopus ID)
Note

QC 20180529

Available from: 2018-05-29 Created: 2018-05-29 Last updated: 2018-10-16Bibliographically approved
Tokitani, M., Miyamoto, M., Masuzaki, S., Sakamoto, R., Oya, Y., Hatano, Y., . . . Rubel, M. (2018). Plasma-wall interaction on the divertor tiles of JET ITER-like wall from the viewpoint of micro/nanoscopic observations. Paper presented at 13th International Symposium on Fusion Nuclear Technology (ISFNT), SEP 25-29, 2017, Kyoto, Japan. Fusion engineering and design, 136, 199-204
Open this publication in new window or tab >>Plasma-wall interaction on the divertor tiles of JET ITER-like wall from the viewpoint of micro/nanoscopic observations
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2018 (English)In: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 136, p. 199-204Article in journal (Refereed) Published
Abstract [en]

Micro/nanoscopic observations on the surface of the divertor tiles used in the first campaign (2011-2012) of the JET tokamak with ITER-like Wall (JET ILW) have been carried out by means of several material analysis techniques. Previous results from the inner divertor were reported for a single poloidal section of the tile numbers 1, 3 and 4, i.e., upper, vertical and horizontal targets, respectively. The formation of the thick stratified mixed-material deposition layer on tiles 1 and 4, and erosion on tile 3 were identified. This study is mostly focused on the outer divertor: tiles 6, 7 and 8. In contrast to the inner tile, remarkable surface modifications have not been observed on the vertical target (tiles 7 and 8) where sputtering erosion and impurity deposition would have been almost balanced. Only a specific part of tile 6 (horizontal target) located near the exhaust channel was covered with a stratified ("geological-like") mixed-material deposition layer which mainly included Be and Ni with the thickness of similar to 2 mu m. Special feature of this mixed layer was that a certain amount of nitrogen (N) was clearly detected in the layer. Since the concentration of N varied with the depth position, it could be depended on the amount of that gas puffed for plasma edge cooling during the JET experimental campaign. In addition to the outer divertor tiles, a very interesting feature of the local erosion and deposition effects is reported in this paper.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
JET-ILW, Divertor, Erosion-deposition, Fuel inventory
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-240779 (URN)10.1016/j.fusengdes.2018.01.051 (DOI)000452583700038 ()2-s2.0-85041200889 (Scopus ID)
Conference
13th International Symposium on Fusion Nuclear Technology (ISFNT), SEP 25-29, 2017, Kyoto, Japan
Note

QC 20190110

Available from: 2019-01-10 Created: 2019-01-10 Last updated: 2019-01-10Bibliographically approved
Weckmann, A., Petersson, P., Rubel, M., Ström, P., Kurki-Suonio, T., Sarkimaki, K., . . . Airila, M. (2018). Review on global migration, fuel retention and modelling after TEXTOR decommission. NUCLEAR MATERIALS AND ENERGY, 17, 83-112
Open this publication in new window or tab >>Review on global migration, fuel retention and modelling after TEXTOR decommission
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2018 (English)In: NUCLEAR MATERIALS AND ENERGY, Vol. 17, p. 83-112Article, review/survey (Refereed) Published
Abstract [en]

Before decommissioning of the TEXTOR tokamak in 2013, the machine was conditioned with a comprehensive migration experiment where MoF6 and N-15(2) were injected on the very last operation day. Thereafter, all plasmafacing components (PFCs) were available for extensive studies of both local and global migration of impurities - Mo, W, Inconel alloy constituents, 15 N, F - and fuel retention studies. Measurements were performed on 140 limiter tiles out of 864 throughout the whole machine to map global transport. One fifth of the introduced molybdenum could be found. Wherever possible, the findings are compared to results obtained previously in other machines. This review incorporates both published and unpublished results from this TEXTOR study and combines findings with analytical methods as well as modelling results from two codes, ERO and ASCOT. The main findings are: Both local and global molybdenum transport can be explained by toroidal plasma flow and (sic) x (sic) drift. The suggested transport scheme for molybdenum holds also for other analysed species, namely tungsten from previous experiments and medium-Z metals (Cr-Cu) introduced on various occasions. Analytical interpretation of several deposition profile features is possible with basic geometrical and plasma physics considerations. These are deposition profiles on the collector probe, the lower part of the inner bumper limiter, the poloidal cross-section of the inner bumper limiter, and the poloidal limiter. Any deposition pattern found in this TEXTOR study, including fuel retention, has neither poloidal nor toroidal symmetry, which is often assumed when determining deposition profiles on global scale. Fuel retention is highly inhomogeneous due to local variation of plasma parameters - by auxiliary heating systems and impurity injection - and PFC temperature. Local modelling with ERO yields good qualitative agreement but too high local deposition efficiency. Global modelling with ASCOT shows that the radial electric field and source form have a high impact on global deposition patterns, while toroidal flow has little influence. Some of the experimental findings could be reproduced. Still, qualitative differences between simulated and experimental global deposition patterns remain. The review closes with lessons learnt during this extensive TEXTOR study which might be helpful for future scientific exploitation of other tokamaks to be decommissioned.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Global migration, Tokamak, high-Z material, Molybdenum, Modelling, ASCOT, ERO, Fuel retention, Deposition
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-241223 (URN)10.1016/j.nme.2018.09.003 (DOI)000454165000013 ()2-s2.0-85054327579 (Scopus ID)
Note

QC 20190115

Available from: 2019-01-15 Created: 2019-01-15 Last updated: 2019-01-15Bibliographically approved
Brezinsek, S., Wirtz, M., Dorrow-Gesprach, D., Loewenhoff, T. & Rubel, M. (2017). 16th International Conference on Plasma-Facing Materials and Components for Fusion Applications. Physica Scripta, T170, Article ID 010201.
Open this publication in new window or tab >>16th International Conference on Plasma-Facing Materials and Components for Fusion Applications
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2017 (English)In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, article id 010201Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Institute of Physics (IOP), 2017
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-220608 (URN)10.1088/1402-4896/aa9958 (DOI)000417694700001 ()
Note

QC 20180115

Available from: 2018-01-15 Created: 2018-01-15 Last updated: 2018-02-21Bibliographically approved
Masuzakil, S., Tokitanii, M., Otsuka, T., Oya, Y., Hatan, Y., Miyamoto, M., . . . Rubel, M. (2017). Analyses of microstructure, composition and retention of hydrogen isotopes in divertor tiles of JET with the ITER-like wall. Paper presented at 16th International Conference on Plasma-Facing Materials and Components for Fusion Applications, MAY 16-19, 2017, GERMANY. Physica Scripta, T170, Article ID 014031.
Open this publication in new window or tab >>Analyses of microstructure, composition and retention of hydrogen isotopes in divertor tiles of JET with the ITER-like wall
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2017 (English)In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, article id 014031Article in journal (Refereed) Published
Abstract [en]

Results of the comprehensive surface analyses of divertor tiles and dusts retrieved from JET after the first ITER-like wall campaign (2011-2012) are presented. The samples cored from the divertor tiles were analyzed. Numerous nano-size bubble-like structures were observed in the deposition layer on the apron of the inner divertor tile, and a beryllium dust with the same structures were found in the matter collected from the inner divertor after the campaign. This suggests that the nano-size bubble-like structures can make the deposition layer to become brittle and may lead to cracking followed by dust generation. X-ray photoelectron spectroscopy analyses of chemical states of species in the deposition layers identified the formation of beryllium-tungsten intermetallic compounds on an inner vertical tile. Different tritium retention profiles along the divertor tiles were observed at the top surfaces and at deeper regions of the tiles by using the imaging plate technique.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keywords
JET, ITER-like wall, dust, XPS, divertor tiles, tritium retention, microstructure
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-217723 (URN)10.1088/1402-4896/aa8bcc (DOI)000414120500031 ()2-s2.0-85045301547 (Scopus ID)
Conference
16th International Conference on Plasma-Facing Materials and Components for Fusion Applications, MAY 16-19, 2017, GERMANY
Note

QC 20171123

Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2017-11-23Bibliographically approved
Catarino, N., Barradas, N. P., Corregidor, V., Widdowson, A., Baron-Wiechec, A., Coad, J. P., . . . Alves, E. (2017). Assessment of erosion, deposition and fuel retention in the JET-ILW divertor from ion beam analysis data. NUCLEAR MATERIALS AND ENERGY, 12, 559-563
Open this publication in new window or tab >>Assessment of erosion, deposition and fuel retention in the JET-ILW divertor from ion beam analysis data
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2017 (English)In: NUCLEAR MATERIALS AND ENERGY, ISSN 2352-1791, Vol. 12, p. 559-563Article in journal (Refereed) Published
Abstract [en]

Post-mortem analyses of individual components provide relevant information on plasma-surface interactions like tungsten erosion, beryllium deposition and plasma fuel retention with divertor tiles via implantation or co-deposition. Ion Beam techniques are ideal tools for such purposes and have been extensively used for post-mortem analyses of selected tiles from JET following each campaign. In this contribution results from tiles removed from the JET ITER-Like Wall (JET-ILW) divertor following the 2013-2014 campaign are presented. The results summarize erosion, deposition and fuel retention along the poloidal cross section of the divertor surface and provide data for comparison with the first JET-ILW campaign, showing a similar pattern of material migration with the exception of Tile 6 where the strike point time on the tile was similar to 4 times longer in 2013-2014 than in 2011-2012, which is likely to account for more material migration to this region. The W deposition on top of the Mo marker coating of Tile 4 shows that the enrichment takes place at the strike point location.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-220641 (URN)10.1016/j.nme.2016.10.027 (DOI)000417293300088 ()2-s2.0-85006922988 (Scopus ID)
Note

QC 20180111

Available from: 2018-01-11 Created: 2018-01-11 Last updated: 2018-03-12Bibliographically approved
Tsavalas, P., Lagoyannis, A., Mergia, K., Rubel, M., Triantou, K., Harissopulos, S., . . . Petersson, P. (2017). Be ITER-like wall at the JET tokamak under plasma. Paper presented at 16th International Conference on Plasma-Facing Materials and Components for Fusion Applications, MAY 16-19, 2017, GERMANY. Physica Scripta, T170, Article ID 014049.
Open this publication in new window or tab >>Be ITER-like wall at the JET tokamak under plasma
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2017 (English)In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, article id 014049Article in journal (Refereed) Published
Abstract [en]

The JET tokamak is operated with beryllium and tungsten plasma-facing components to prepare for the exploitation of ITER. To determine beryllium erosion and migration in JET a set of markers were installed. Specimens from different beryllium marker tiles of the main wall of the ITER-like wall (ILW) JET tokamak from the first and the second D-D campaign were analyzed with nuclear reaction analysis, x-ray fluorescence spectroscopy, scanning electron microscopy and x-ray diffraction (XRD). Emphasis was on the determination of carbon plasma impurities deposited on beryllium surfaces. The C-12(d, p(0))C-13 reaction was used to quantify carbon deposition and to determine depth profiles. Carbon quantities on the surface of the Be tiles are low, varying from (0.35 +/- 0.07) x 10(17) to (11.8 +/- 0.6) x 10(17) at cm(-2) in the deposition depth from 0.4 to 6.7 mu m, respectively. In the 0.4-0.5 mm wide grooves of castellation sides the carbon content is found up to (14.3 +/- 2.5) x 10(17) at cm(-2) while it is higher (up to (38 +/- 4) x 10(17) at cm(-2)) in wider gaps (0.8 mm) separating tile segments. Oxygen (O), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni) and tungsten (W) were detected in all samples exposed to plasma and the reference one but at lower quantities at the latter. In the central part of the Inner Wall Guard Limiter from the first ILW campaign and in the Outer Poloidal Limiter from the second ILW campaign the Ni interlayer has been completely eroded. XRD shows the formation of BeNi in most specimens.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keywords
beryllium, JET tokamak, ITER like wall, plasma, nuclear reaction analysis, erosiond-eposition
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-217725 (URN)10.1088/1402-4896/aa8ff4 (DOI)000414120500049 ()
Conference
16th International Conference on Plasma-Facing Materials and Components for Fusion Applications, MAY 16-19, 2017, GERMANY
Note

QC 20171123

Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2017-11-23Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-9901-6296

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