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Petersson, Per
Publications (10 of 20) Show all publications
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
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
Ström, P., Petersson, P., Arredondo Parra, R., Oberkofler, M., Schwarz-Selinger, T. & Primetzhofer, D. (2018). Sputtering of polished EUROFER97 steel: Surface structure modification and enrichment with tungsten and tantalum. Journal of Nuclear Materials, 508, 139-146
Open this publication in new window or tab >>Sputtering of polished EUROFER97 steel: Surface structure modification and enrichment with tungsten and tantalum
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2018 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 508, p. 139-146Article in journal (Refereed) Published
Abstract [en]

Surface structure modification and enrichment with tungsten and tantalum were measured for polished EUROFER97 samples after exposure to a deuterium ion beam. Time-of-flight medium energy ion scattering and time-of-flight elastic recoil detection analysis were implemented for measuring atomic composition profiles. Atomic force microscopy and optical microscopy were used to investigate surface morphology. The deuterium particle fluence was varied between 1021 D/m2 and 1024 D/m2, projectile energy was 200 eV/D and exposure temperatures up to 1050 K were applied. The average fraction of tungsten plus tantalum to total metal content in the 2 nm closest to the sample surface was increased from an initial 0.0046 to 0.12 for the sample exposed to the highest fluence at room temperature. The enrichment was accompanied by an increase in surface roughness of one order of magnitude and grain dependent erosion of the material. The appearance of protrusions with heights up to approximately 40 nm after ion beam exposure at room temperature was observed on individual grains. Samples exposed to 1023 D/m2 at temperatures of 900 K and 1050 K displayed recrystallization and cracking while changes to the total surface fraction of tungsten and tantalum were limited to less than a factor of two compared to the sample exposed to the same fluence at room temperature.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
AFM, Erosion, EUROFER, Sputtering, ToF-ERDA, ToF-MEIS
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-229259 (URN)10.1016/j.jnucmat.2018.05.031 (DOI)000439134500016 ()2-s2.0-85047329344 (Scopus ID)
Funder
Swedish Research Council, 821-2012-5144Swedish Foundation for Strategic Research , RIF14-0053EU, European Research Council
Note

QC 20180601

Available from: 2018-06-01 Created: 2018-06-01 Last updated: 2019-01-09Bibliographically 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
Louche, F., Wauters, T., Ragona, R., Moeller, S., Durodie, F., Litnovsky, A., . . . Van Schoor, M. (2017). Design of an ICRF system for plasma-wall interactions and RF plasma production studies on TOMAS. Paper presented at 29th Symposium on Fusion Technology (SOFT), SEP 05-09, 2016, Prague, CZECH REPUBLIC. Fusion engineering and design, 123, 317-320
Open this publication in new window or tab >>Design of an ICRF system for plasma-wall interactions and RF plasma production studies on TOMAS
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2017 (English)In: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 123, p. 317-320Article in journal (Refereed) Published
Abstract [en]

Ion cyclotron wall conditioning (ICWC) is being developed for ITER and W7-X as a baseline conditioning technique in which the ion cyclotron heating and current drive system will be employed to produce and sustain the currentless conditioning plasma. The TOMAS project (TOroidal MAgnetized System, operated at the FZ-juelich, Germany) proposes to explore several key aspects of ICWC. For this purpose we have designed an ICRF system made of a single strap antenna within a metallic box, connected to a feeding port and a pre-matching system. We discuss the design work of the antenna system with the help of the commercial electromagnetic software CST Microwave Studio (R). The simulation results for a given geometry provide input impedance matrices for the two-port system. These matrices are afterwards inserted into various circuit models to assess the accessibility of the required frequency range. The sensitivity of the matching system to uncertainties on plasma loading and capacitance values is notably addressed. With a choice of three variable capacitors we show that the system can cope with such uncertainties. We also demonstrate that the system can cope as well with the high reflected power levels during the short breakdown phase of the RF discharge, but at the cost of a significantly reduced coupled power.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2017
Keywords
ICWC, Antennas, Capacitors, TOMAS, Matching, Simulations
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-221890 (URN)10.1016/j.fusengdes.2017.04.123 (DOI)000418992000063 ()
Conference
29th Symposium on Fusion Technology (SOFT), SEP 05-09, 2016, Prague, CZECH REPUBLIC
Note

QC 20180130

Available from: 2018-01-30 Created: 2018-01-30 Last updated: 2018-01-30Bibliographically approved
Fortuna-Zalesna, E., Grzonka, J., Moon, S., Rubel, M., Petersson, P. & Widdowson, A. (2017). Fine metal dust particles on the wall probes from JET-ILW. 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 014038.
Open this publication in new window or tab >>Fine metal dust particles on the wall probes from JET-ILW
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2017 (English)In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, article id 014038Article in journal (Refereed) Published
Abstract [en]

Collection and ex situ studies of dust generated in controlled fusion devices during plasma operation are regularly carried out after experimental campaigns. Herewith results of the dust survey performed in JET after the second phase of operation with the metal ITER-like wall (2013-2014) are presented. For the first-time-ever particles deposited on silicon plates acting as dust collectors installed in the inner and outer divertor have been examined. The emphasis is on analysing metal particles (Be and W) with the aim to determine their composition, size and surface topography. The most important is the identification of beryllium dust in the form of droplets (both splashes and spherical particles), flakes of co-deposits and small fragments of Be tiles. Tungsten and nickel rich (from Inconel) particles are also identified. Nitrogen from plasma edge cooling has been detected in all types of particles. They are categorized and the origin of various constituents is discussed.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keywords
plasma, dust, JET tokamak, ITER-like wall, beryllium, tungsten
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-217721 (URN)10.1088/1402-4896/aa8ddf (DOI)000414120500038 ()
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
Rubel, M., Petersson, P., Zhou, Y., Coad, J. P., Lungu, C., Jepu, I., . . . Alves, E. (2017). Fuel inventory and deposition in castellated structures in JET-ILW. Nuclear Fusion, 57(6), Article ID 066027.
Open this publication in new window or tab >>Fuel inventory and deposition in castellated structures in JET-ILW
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2017 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 57, no 6, article id 066027Article in journal (Refereed) Published
Abstract [en]

Since 2011 the JET tokamak has been operated with a metal ITER-like wall (JET-ILW) including castellated beryllium limiters and lamellae-type bulk tungsten tiles in the divertor. This has allowed for a large scale test of castellated plasma-facing components (PFC). Procedures for sectioning the limiters into single blocks of castellation have been developed. This facilitated morphology studies of morphology of surfaces inside the grooves for limiters after experimental campaigns 2011-2012 and 2013-2014. The deposition in the 0.4-0.5 mm wide grooves of the castellation is 'shallow'. It reaches 1-2 mm into the 12 mm deep gap. Deuterium concentrations are small (mostly below 1 × 1018 cm-2). The estimated total amount of deuterium in all the castellated limiters does not exceed the inventory of the plasma-facing surfaces (PFS) of the limiters. There are only traces of Ni, Cr and Fe deposited in the castellation gaps. The same applies to the carbon content. Also low deposition of D, Be and C has been measured on the sides of the bulk tungsten lamellae pieces. Modelling clearly reflects: (a) a sharp decrease in the measured deposition profiles and(b) an increase in deposition with the gap width. Both experimental and modelling data give a strong indication and information to ITER that narrow gaps in the castellated PFC are essential. X-ray diffraction on PFS has clearly shown two distinct composition patterns: Be with an admixture of Be-W intermetallic compounds (e.g. Be22W) in the deposition zone, whilst only pure Be has been detected in the erosion zone. The lack of compound formation in the erosion zone indicates that no distinct changes in the thermo-mechanical properties of the Be PFC might be expected.

Place, publisher, year, edition, pages
Institute of Physics Publishing, 2017
Keywords
beryllium limiters, castellation, deposition, fuel inventory, ITER-like wall, JET, Beryllium, Carbon, Deuterium, Erosion, Facings, Fighter aircraft, Fusion reactor divertors, Intermetallics, Jets, Magnetoplasma, Tungsten, Tungsten compounds, X ray diffraction, Experimental campaign, Fuel inventories, Morphology of surfaces, Plasma facing surfaces, Plasma-facing components, Thermomechanical properties, Tokamak devices
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-216517 (URN)10.1088/1741-4326/aa6864 (DOI)000425870600001 ()2-s2.0-85019426928 (Scopus ID)
Note

QC 20171201

Available from: 2017-12-01 Created: 2017-12-01 Last updated: 2018-03-09Bibliographically approved
Widdowson, A., Coad, J. P., Alves, E., Baron-Wiechec, A., Barradas, N. P., Catarino, N., . . . Rubel, M. (2017). Impurity re-distribution in the corner regions of the JET divertor. Paper presented at 16th International Conference on Plasma-Facing Materials and Components for Fusion Applications (PFMC), MAY, 2017, GERMANY. Physica Scripta, T170, Article ID 014060.
Open this publication in new window or tab >>Impurity re-distribution in the corner regions of the JET divertor
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2017 (English)In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, article id 014060Article in journal (Refereed) Published
Abstract [en]

The International Thermonuclear Experimental Reactor (ITER) will use a mixture of deuterium (D) and tritium (T) as the fuel to generate power. Since T is both radioactive and expensive the Joint European Torus (JET) has been at the forefront of research to discover how much T is used and where it may be retained within the main reaction chamber. Until the year 2010 the JET plasma facing components were constructed of carbon fibre composites. During the JET carbon (C) phases impurities accumulated at the corners of the divertor located towards the bottom of the chamber in regions shadowed from the plasma where they are very difficult to reach and remove. This build-up of C and the associated H-isotope (including T) retention were of particular concern for future fusion reactors therefore, in 2010 JET changed the wall protection to (mainly) Be and the divertor to tungsten (W)-the JET ITER-like wall (ILW)-the choice of materials for ITER. This paper reveals that with the JET ILW impurities are still accumulating in the shadowed regions, with Be being the majority element, though the overall quantities are very much reduced from those in the C phases. Material will be transported into the shadowed regions principally when the plasma strike points are on the corner tiles, but particles typically have about a 75% probability of reflection from line-of sight surfaces, and multiple reflection/scattering results in deposition over all surfaces.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2017
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-220612 (URN)10.1088/1402-4896/aa90d5 (DOI)000417694700005 ()
Conference
16th International Conference on Plasma-Facing Materials and Components for Fusion Applications (PFMC), MAY, 2017, GERMANY
Note

QC 20180112

Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2018-02-26Bibliographically approved
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