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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.
Åpne denne publikasjonen i ny fane eller vindu >>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 (engelsk)Inngår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 89, nr 4, artikkel-id 049901Artikkel i tidsskrift (Fagfellevurdert) Published
sted, utgiver, år, opplag, sider
American Institute of Physics (AIP), 2018
HSV kategori
Identifikatorer
urn:nbn:se:uu:diva-382292 (URN)10.1063/1.5030502 (DOI)000431139400078 ()29716341 (PubMedID)2-s2.0-85045335587 (Scopus ID)
Merknad

QC 201805014

Tilgjengelig fra: 2019-04-24 Laget: 2019-04-24 Sist oppdatert: 2019-04-24
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
Åpne denne publikasjonen i ny fane eller vindu >>Review on global migration, fuel retention and modelling after TEXTOR decommission
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2018 (engelsk)Inngår i: NUCLEAR MATERIALS AND ENERGY, Vol. 17, s. 83-112Artikkel, forskningsoversikt (Fagfellevurdert) 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 This review incorporates both published and unpublished results from this TEXTOR study and combines findings with analytical methods as well as modelling results from two codes, ERO and ASCOT.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.

sted, utgiver, år, opplag, sider
ELSEVIER SCIENCE BV, 2018
Emneord
Global migration, Tokamak, high-Z material, Molybdenum, Modelling, ASCOT, ERO, Fuel retention, Deposition
HSV kategori
Identifikatorer
urn:nbn:se:uu:diva-382298 (URN)10.1016/j.nme.2018.09.003 (DOI)000454165000013 ()2-s2.0-85054327579 (Scopus ID)
Merknad

QC 20190115

Tilgjengelig fra: 2019-04-24 Laget: 2019-04-24 Sist oppdatert: 2019-04-24
Fortuna-Zalesna, E., Weckmann, A., Grozonka, J., Rubel, M., Esser, H. G., Freisinger, M., . . . Ström, P. (2016). Dust Survey Following the Final Shutdown of TEXTOR: Metal Particles and Fuel Retention. Physica Scripta, T167, Article ID 014059.
Åpne denne publikasjonen i ny fane eller vindu >>Dust Survey Following the Final Shutdown of TEXTOR: Metal Particles and Fuel Retention
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2016 (engelsk)Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T167, artikkel-id 014059Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The work presents results of a broad TEXTOR dust survey in terms of its composition, structure, distribution and fuel content. The dust particles were collected after final shutdown of TEXTOR in December 2013. Fuel retention, as determined by thermal desorption, varied significantly, even by two orders of magnitude, dependent on the dust location in the machine. Dust structure was examined by means of scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, focused ion beam and scanning transmission electron microscopy. Several categories of dust have been identified. Carbon-based stratified and granular deposits were dominating, but the emphasis in studies was on metal dust. They were found in the form of small particles, small spheres, flakes and splashes which formed “comet”-like structures clearly indicating directional effects in the impact on surfaces of plasma-facing components. Nickel-rich alloys from the Inconel liner and iron-based ones from various diagnostic holders were the main components of metal-containing dust, but also molybdenum and tungsten debris were detected. Their origin is discussed.

sted, utgiver, år, opplag, sider
Institute of Physics Publishing (IOPP), 2016
Emneord
TEXTOR, dust, fuel retention, high-Z metals
HSV kategori
Identifikatorer
urn:nbn:se:uu:diva-382283 (URN)10.1088/0031-8949/T167/1/014059 (DOI)000383504700060 ()2-s2.0-84959896914 (Scopus ID)
Merknad

QC 20160127

Tilgjengelig fra: 2019-04-24 Laget: 2019-04-24 Sist oppdatert: 2019-04-24
Ström, P., Petersson, P., Rubel, M., Weckmann, A., Brezinsek, S., Kreter, A., . . . Rozniatowski, K. (2015). Characterisation of surface layers formed on plasma-facing components in controlled fusion devices: Role of heavy ion elastic recoil detection. Vacuum, 122, 260-267
Åpne denne publikasjonen i ny fane eller vindu >>Characterisation of surface layers formed on plasma-facing components in controlled fusion devices: Role of heavy ion elastic recoil detection
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2015 (engelsk)Inngår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 122, s. 260-267Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Wall components retrieved from the TEXTOR tokamak after tracer experiments with nitrogen-15 and molybdenum hexafluoride (MoF6) injection were studied to determine deposition patterns and, by this, to conclude on material migration. Toroidal limiter tiles made of carbon fibre composites and fine grain graphite were examined using time-of-flight heavy ion elastic recoil detection analysis. Molybdenum deposition patterns indicated migration based on erosion and prompt re-deposition. Nitrogen-15 was trapped together with the deposited molybdenum. Some information on the depth distribution of species in the top 400 nm layer of the limiters was obtained; however surface roughness of the samples strongly limited resolution. In the case of molybdenum, the largest concentration was found in the 100 nm outermost layer, whereas fluorine and nitrogen-15 displayed more irregular profiles. Other species, besides deuterium fuel and carbon-12, were also identified: boron-10 and boron-11 originating from boronisations, carbon-13 from earlier tracer experiments, nitrogen-14 from plasma edge cooling and metals eroded from the Inconel wall.

HSV kategori
Identifikatorer
urn:nbn:se:uu:diva-382295 (URN)10.1016/j.vacuum.2015.04.019 (DOI)2-s2.0-84945489472 (Scopus ID)
Merknad

QC 20150203

Tilgjengelig fra: 2019-04-24 Laget: 2019-04-24 Sist oppdatert: 2019-04-24
Rubel, M., Weckmann, A., Ström, P., Petersson, P., Garcia Carrasco, A., Brezinsek, S., . . . Fortuna-Zalesna, E. (2015). Tracer techniques for the assessment of material migration and surface modification of plasma-facing components. Journal of Nuclear Materials, 463, 280-284
Åpne denne publikasjonen i ny fane eller vindu >>Tracer techniques for the assessment of material migration and surface modification of plasma-facing components
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2015 (engelsk)Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 463, s. 280-284Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Tracer techniques were used in the TEXTOR tokamak to determine high-Z metal migration and the deposition of species used for plasma edge cooling or wall conditioning under different types of operation conditions. Volatile molybdenum hexa-fluoride, nitrogen-15 and oxygen-18 were used as markers in tokamak or ion cyclotron wall conditioning discharges (ICWC). The objective was to obtain qualitative and quantitative of a global and local deposition pattern and material mixing effects. The deposition and retention was studied on plasma-facing components, collector probes and test limiters. Optical spectroscopy and ex-situ analysis techniques were used to determine the plasma response to tracer injection and the modification of surface composition. Molybdenum and light isotopes were detected on all types of limiters and short-term probes retrieved from the vessel showing that both helium and nitrogen are trapped following wall conditioning and edge cooling. Only small amounts below 1 x 10(19) m(-2) of O-18 were detected on surfaces treated by oxygen-assisted ICWC.

sted, utgiver, år, opplag, sider
Elsevier, 2015
HSV kategori
Identifikatorer
urn:nbn:se:uu:diva-382287 (URN)10.1016/j.jnucmat.2014.11.074 (DOI)000358467200052 ()2-s2.0-84937517699 (Scopus ID)
Forskningsfinansiär
Swedish Research Council, 621-2009-4138
Merknad

QC 20150901

Tilgjengelig fra: 2019-04-24 Laget: 2019-04-24 Sist oppdatert: 2019-04-24
Organisasjoner
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0001-9901-6296