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  • 1. Huber, A.
    et al.
    Brezinsek, S.
    Kirschner, A.
    Ström, Petter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Fusionsplasmafysik.
    Sergienko, G.
    Huber, V.
    Borodkina, I.
    Douai, D.
    Jachmich, S.
    Linsmeier, Ch.
    Lomanowski, B.
    Matthews, G.F
    Mertens, P.h
    Determination of tungsten sources in the JET-ILW divertor by spectroscopic imaging in the presence of a strong plasma continuum2019Inngår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 18, s. 118-124Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The identification of the sources of atomic tungsten and the measurement of their radiation distribution in front of all plasma-facing components has been performed in JET with the help of two digital cameras with the same two-dimensional view, equipped with interference filters of different bandwidths centred on the W I (400.88 nm) emission line. A new algorithm for the subtraction of the continuum radiation was successfully developed and is now used to evaluate the W erosion even in the inner divertor region where the strong recombination emission is dominating over the tungsten emission. Analysis of W sputtering and W redistribution in the divertor by video imaging spectroscopy with high spatial resolution for three different magnetic configurations was performed. A strong variation of the emission of the neutral tungsten in toroidal direction and corresponding W erosion has been observed. It correlates strongly with the wetted area with a maximal W erosion at the edge of the divertor tile.

  • 2. Koslowski, H.R.
    et al.
    Bhattacharyya, S.R.
    Hansen, P.
    Linsmeier, Ch.
    Rasinski, M.
    Ström, Petter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Fusionsplasmafysik.
    Temperature-dependent in-situ LEIS measurement of W surface enrichment by 250 eV D sputtering of EUROFER2018Inngår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 16, s. 181-190Artikkel i tidsskrift (Fagfellevurdert)
  • 3.
    Moon, Sunwoo
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Fusionsplasmafysik.
    Petersson, Per
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Fusionsplasmafysik.
    Rubel, Marek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Fusionsplasmafysik.
    Fortuna-Zalesna, E.
    Widdowson, A.
    Jachmich, S.
    Litnovsky, A.
    Alves, E.
    Contributors, J E T
    First mirror test in JET for ITER: Complete overview after three ILW campaigns2019Inngår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 19, s. 59-66Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The First Mirror Test for ITER has been carried out in JET with mirrors exposed during: (i) the third ILW campaign (ILW-3, 2015–2016, 23.33 h plasma) and (ii) all three campaigns, i.e. ILW-1 to ILW-3: 2011–2016, 63,52 h in total. All mirrors from main chamber wall show no significant changes of the total reflectivity from the initial value and the diffuse reflectivity does not exceed 3% in the spectral range above 500 nm. The modified layer on surface has very small amount of impurities such as D, Be, C, N, O and Ni. All mirrors from the divertor (inner, outer, base under the bulk W tile) lost reflectivity by 20–80% due to the beryllium-rich deposition also containing D, C, N, O, Ni and W. In the inner divertor N reaches 5 × 10 17 cm −2 , W is up to 4.3 × 10 17 cm −2 , while the content of Ni is the greatest in the outer divertor: 3.8 × 10 17 cm −2 . Oxygen-18 used as the tracer in experiments at the end of ILW-3 has been detected at the level of 1.1 × 10 16 cm −2 . The thickness of deposited layer is in the range of 90 nm to 900 nm. The layer growth rate in the base (2.7 pm s − 1 ) and inner divertor is proportional to the exposure time when a single campaign and all three are compared. In a few cases, on mirrors located at the cassette mouth, flaking of deposits and erosion occurred.

  • 4.
    Otsuka, T.
    et al.
    Kindai Univ, 3-4-1 Kowakae, Higashiosaka, Osaka 5778502, Japan..
    Masuzaki, S.
    Natl Inst Fus Sci, 322-6 Oroshi Cho, Toki, Gifu 5095292, Japan..
    Ashikawa, N.
    Natl Inst Fus Sci, 322-6 Oroshi Cho, Toki, Gifu 5095292, Japan..
    Hatano, Y.
    Univ Toyama, Gofuku 3190, Toyama 9308555, Japan..
    Asakura, Y.
    Natl Inst Quantum, Aomori 0393212, Japan.;Natl Inst Radiol Sci & Technol, Aomori 0393212, Japan..
    Suzuki, Tatsuya
    Natl Inst Quantum, Aomori 0393212, Japan.;Natl Inst Radiol Sci & Technol, Aomori 0393212, Japan..
    Suzuki, Takumi
    Natl Inst Quantum, Aomori 0393212, Japan.;Natl Inst Radiol Sci & Technol, Aomori 0393212, Japan..
    Isobe, K.
    Natl Inst Quantum, Aomori 0393212, Japan.;Natl Inst Radiol Sci & Technol, Aomori 0393212, Japan..
    Hayashi, T.
    Natl Inst Quantum, Aomori 0393212, Japan.;Natl Inst Radiol Sci & Technol, Aomori 0393212, Japan..
    Tokitani, M.
    Natl Inst Fus Sci, 322-6 Oroshi Cho, Toki, Gifu 5095292, Japan..
    Oya, Y.
    Shizuoka Univ, Shizuoka 4228529, Japan..
    Hamaguchi, D.
    Natl Inst Quantum, Aomori 0393212, Japan.;Natl Inst Radiol Sci & Technol, Aomori 0393212, Japan..
    Kurotaki, H.
    Natl Inst Quantum, Aomori 0393212, Japan.;Natl Inst Radiol Sci & Technol, Aomori 0393212, Japan..
    Sakamoto, R.
    Natl Inst Fus Sci, 322-6 Oroshi Cho, Toki, Gifu 5095292, Japan..
    Tanigawa, Hiroyasu
    Natl Inst Quantum, Aomori 0393212, Japan.;Natl Inst Radiol Sci & Technol, Aomori 0393212, Japan..
    Nakamichi, M.
    Natl Inst Quantum, Aomori 0393212, Japan.;Natl Inst Radiol Sci & Technol, Aomori 0393212, Japan..
    Widdowson, A.
    Culham Sci Ctr, Culham Ctr Fus Energy, Abingdon OX14 3DB, Oxon, England..
    Rubel, Marek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Fusionsplasmafysik.
    Tritium retention characteristics in dust particles in JET with ITER-like wall2018Inngår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 17, s. 279-283Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A tritium imaging plate technique (TIPT) in combination with an electron-probe microscopic analysis (EPMA) were applied to examine tritium (T) retention characteristics in individual dust particles collected in the Joint European Torus with the ITER-like Wall (JET-ILW) after the first campaign in 2011-2012. A lot of carbon pre-existing carbon deposits in the JET-C or released carbon particles from the remaining carbon-fiber components in the JET-ILW. Most of T was retained at the surface of and/or in the C-dominated dust particles. The retention in tungsten, beryllium and other metal-dominated dust particles is relatively lower by a factor of 10-100 in comparison with that in the Cdominated particles.

  • 5.
    Ratynskaia, Svetlana V.
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    Tolias, Panagiotis
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    De Angeli, M.
    CNR, Ist Fis Plasma, Via Cozzi 53, I-20125 Milan, Italy..
    Ripamonti, D.
    CNR, Inst Condensed Matter Chem & Energy Technol, Via Cozzi 53, I-20125 Milan, Italy..
    Riva, G.
    CNR, Inst Condensed Matter Chem & Energy Technol, Via Cozzi 53, I-20125 Milan, Italy..
    Aussems, D.
    DIFFER, De Zaale 20, NL-5612 AJ Eindhoven, Netherlands..
    Morgan, T. W.
    DIFFER, De Zaale 20, NL-5612 AJ Eindhoven, Netherlands..
    Interaction of adhered beryllium proxy dust with transient and stationary plasmas2018Inngår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 17, s. 222-227Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tungsten (W) substrates with adhered beryllium (Be) proxy dust-copper, chromium, aluminium -have been exposed in the Magnum-PSI linear device. Their interaction with transient and stationary plasmas has been systematically studied under varying heat fluxes and magnetic field topologies. The dust remobilization activities, macro-morphological changes and chemical modifications induced by the plasma incidence are documented. Aluminium is identified to be the most suitable surrogate material due to the similar binary phase diagram and nearly identical evaporation rates. Extrapolation suggests that Be dust cannot survive on hot W surfaces but it can trigger mixed Be/W effects prior to its plasma removal.

  • 6.
    Ström, Petter
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Primetzhofer, D.
    Schwarz-Selinger, T.
    Sugiyama, K.
    Compositional and morphological analysis of FeW films modified by sputtering and heating2017Inngår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 12, s. 472-477Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Surface compositional changes of iron-tungsten films by deuterium (D) ion bombardment were studied by means of medium energy ion scattering, elastic recoil detection analysis and Rutherford backscattering spectrometry. The energy of the bombarding ions was 200 eV/D and the fluence was varied from 1e21 D/m2 to 1e24 D/m2. A significant increase of the tungsten concentration within the 20 nm closest to the sample surface, caused by preferential sputtering of iron, was seen for the films exposed 1e23 D/m2 or more. In the sample exposed to the highest fluence, 1e24 D/m2, the concentration of tungsten was increased from an initial 1.7 at. % up to approximately 24 at. % averaged over the 5 nm closest to the surface. The analysis was complicated by the presence of oxygen on the sample surfaces. In order to study the thermal stability of the tungsten enriched layer, the sample initially exposed to 1e23 D/m2 at room temperature was heated to 400 °C in the measurement chamber for medium energy ion scattering and several spectra were recorded at intermediate temperatures. The obtained data showed that the layer was relatively stable below 200 °C whereas a drastic change in the film composition occurred between 200 °C and 250 °C due to interdiffusion of iron and silicon, the latter of which was the substrate material. The surface morphologies of the films were probed with atomic force microscopy showing that protrusions of 10–100 nm width appeared after deuterium bombardment at fluences higher than 1e22 D/m2.

  • 7.
    Thorén, Emil
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    Ratynskaia, Svetlana V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    Tolias, Panagiotis
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    Pitts, R. A.
    ITER Org, Route Vinon Sur Verdon,CS 90 046, F-13067 St Paul Les Durance, France..
    Krieger, K.
    Max Planck Inst Plasma Phys, D-85748 Garching, Germany..
    Komm, M.
    Inst Plasma Phys CAS, Za Slovankou 3, Prague 18200 8, Czech Republic..
    Baken, M.
    Max Planck Inst Plasma Phys, D-85748 Garching, Germany..
    MEMOS 3D modelling of ELM-induced transient melt damage on an inclined tungsten surface in the ASDEX Upgrade outer divertor2018Inngår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 17, s. 194-199Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first MEMOS 3D simulations of liquid metal motion on an inclined bulk tungsten sample transiently molten by edge-localized modes (ELMs) are reported. The exposures took place at the outer ASDEX-Upgrade divertor with the tungsten surface tangent intersecting the magnetic field at similar to 18 degrees. Simulations confirm that the observed poloidal melt motion is caused by the volumetric J x B force with J the bulk replacement current triggered by thermionic emission. The final erosion profile and total melt build up are reproduced by employing the escaping thermionic current dependence on the incident heat flux derived from dedicated particle-in-cell simulations. Modelling reveals that melt dynamics is governed by the volumetric Lorentz force, capillary flows due to thermal surface tension gradients and viscous deceleration. The effect of the evolving surface deformation, that locally alters the field-line inclination modifying the absorbed power flux and the escaping thermionic current, in the final surface morphology is demonstrated to be significant.

  • 8.
    Tolias, Panagiotis
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    De Angeli, M.
    CNR, Ist Fis Plasma, Via Corsi 53, I-20125 Milan, Italy..
    Riva, G.
    CNR, Inst Condensed Matter Chem & Energy Technol, Via Cozzi 53, I-20125 Milan, Italy..
    Ratynskaia, Svetlana V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    Daminelli, G.
    CNR, Inst Condensed Matter Chem & Energy Technol, Via Cozzi 53, I-20125 Milan, Italy..
    Laguardia, L.
    CNR, Ist Fis Plasma, Via Corsi 53, I-20125 Milan, Italy..
    Pedron, M.
    CNR, Ist Fis Plasma, Via Corsi 53, I-20125 Milan, Italy..
    Ripamonti, D.
    CNR, Inst Condensed Matter Chem & Energy Technol, Via Cozzi 53, I-20125 Milan, Italy..
    Uccello, A.
    CNR, Ist Fis Plasma, Via Corsi 53, I-20125 Milan, Italy..
    Vassallo, E.
    CNR, Ist Fis Plasma, Via Corsi 53, I-20125 Milan, Italy..
    The adhesion of tungsten dust on plasma-exposed tungsten surfaces2019Inngår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 18, s. 18-22Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The adhesion of tungsten dust is measured on plasma-exposed and non-exposed tungsten substrates with the electrostatic detachment method. Tungsten substrates of comparable surface roughness have been exposed to the deuterium plasmas of the GyM linear device and the argon plasmas of rf glow discharges under conditions which invariably modify the surface composition due to physical sputtering. The adhesion has been systematically characterized for different spherical nearly monodisperse dust populations. Independent of the dust size, an approximate 50% post-exposure reduction of the average and spread of the adhesive force has been consistently observed and attributed to surface chemistry modifications.

  • 9.
    Tolias, Panagiotis
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    Riva, G.
    De Angeli, M.
    Ratynskaia, Svetlana V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    Daminelli, G.
    Lungu, C. P.
    Porosnicu, C.
    Adhesive force distributions for tungsten dust deposited on bulk tungsten and beryllium-coated tungsten surfaces2018Inngår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 15, s. 55-63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Comprehensive measurements of the adhesive force for tungsten dust adhered to tungsten surfaces have been performed with the electrostatic detachment method. Monodisperse spherical dust has been deposited with gas dynamics techniques or with gravity mimicking adhesion as it naturally occurs in tokamaks. The adhesive force is confirmed to follow the log-normal distribution and empirical correlations are proposed for the size-dependence of its mean and standard deviation. Systematic differences are observed between the two deposition methods and attributed to plastic deformation during sticking impacts. The presence of thin beryllium coatings on tungsten surfaces is demonstrated to barely affect adhesion.

  • 10.
    Weckmann, Armin
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Fusionsplasmafysik.
    Kurki-Suonio, T.
    Särkimäki, K.
    Romazanov, J.
    Kirschner, A.
    Hakola, A.
    Airila, M.
    Kreter, A.
    Brezinsek, S.
    Physics affecting heavy impurity migration in tokamaks: Benchmarking test-ion code ASCOT against TEXTOR tracer experiment2019Inngår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 19, s. 307-315Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Erosion, transport and deposition of wall impurities are major concerns in future magnetic fusion devices, both from the perspective of the fusion plasma and the machine wall. An extensive study on molybdenum transport and deposition performed in the TEXTOR tokamak yielded a detailed deposition map that is ideal for benchmark deposition studies. A qualitative benchmark is attempted in this article with the ASCOT code. We set up a full 3D model of the TEXTOR tokamak and studied the influence of different physical mechanisms and their strengths on molybdenum deposition patterns on the simulated plasma-facing components: atomic processes, Coulomb collisions, scrape-off layer (SOL) profiles, source distribution, marker starting energy, radial electric field strength, SOL flow and toroidal plasma rotation. The outcome comprises 13 simulations, each with 100,000 markers. The findings are: • Toroidal plasma movement, either within the LCFS or as SOL flow, is negligible. • SOL profile and marker starting energy have modest impact on deposition. • Source distribution has a large impact in combination with radial electric field profiles. • The E⇀×B⇀ drift has the highest impact on the deposition profiles. © 2019 The Authors

  • 11.
    Wiesen, S.
    et al.
    Forschungszentrum Julich, Inst Energie & Klimaforsch Plasmaphys, D-52425 Julich, Germany..
    Brezinsek, S.
    Forschungszentrum Julich, Inst Energie & Klimaforsch Plasmaphys, D-52425 Julich, Germany..
    Bonnin, X.
    ITER Org, Route Vinon Sur Verdon,CS90 046, F-13067 St Paul Les Durance, France..
    Delabie, E.
    Oak Ridge Natl Lab, POB 2009, Oak Ridge, TN 37831 USA..
    Frassinetti, Lorenzo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Fusionsplasmafysik.
    Groth, M.
    Aalto Univ, Espoo, Finland..
    Guillemaut, C.
    Univ Lisbon, Inst Plasmas & Fusao Nucl, IST, P-1049001 Lisbon, Portugal..
    Harrison, J.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England..
    Harting, D.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England..
    Henderson, S.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England..
    Huber, A.
    Forschungszentrum Julich, Inst Energie & Klimaforsch Plasmaphys, D-52425 Julich, Germany..
    Kruezi, U.
    ITER Org, Route Vinon Sur Verdon,CS90 046, F-13067 St Paul Les Durance, France..
    Pitts, R. A.
    ITER Org, Route Vinon Sur Verdon,CS90 046, F-13067 St Paul Les Durance, France..
    Wischmeier, M.
    Max Planck Inst Plasma Phys, D-85748 Garching, Germany..
    On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wall2018Inngår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 17, s. 174-181Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The impact of the finite grid size in SOLPS-ITER edge plasma simulations is assessed for JET H-mode discharges with a metal wall. For a semi-horizontal divertor configuration it is shown that the separatrix density is at least 30% higher when a narrow scrape-off layer (SOL) grid width is chosen in SOLPS-ITER compared to the case for which the SOL grid width is maximised. The density increase is caused by kinetic neutrals being not confined inside the divertor region because of the reduced extent of the plasma grid. In this case, an enhanced level of reflections of energetic neutrals at the low-field side (LFS) metal divertor wall is observed. This leads to a shift of the ionisation source further upstream which must be accounted for as a numerical artefact. An overestimate in the cooling at the divertor entrance is observed in this case, identified by a reduced heat flux decay parameters lambda(div)(q). Otherwise and further upstream the mid-plane heat decay length lambda(q) parameter is not affected by any change in divertor dissipation. This confirms the assumptions made for the ITER divertor design studies, i.e. that lambda(q) upstream is essentially set by the assumptions for the ratio radial to parallel heat conductivity. It is also shown that even for attached conditions the decay length relations lambda(ne)>lambda(Te)>lambda(q) hold in the near-SOL upstream. Thus for interpretative edge plasma simulations one must take the (experimental) value of lambda(ne) into account, rather than lambda(q), as the former actually defines the required minimum upstream SOL grid extent.

  • 12.
    Zhou, Yushan
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Fusionsplasmafysik.
    Bergsåker, Henric
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Fusionsplasmafysik.
    Petersson, Per
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Fusionsplasmafysik.
    Possnert, G
    Likonen, J
    contributors, JET
    The effect of gyration on the deposition of beryllium and deuterium at rough surface on thedivertor tiles with ITER-like-wall in JET2019Inngår i: Nuclear Materials and Energy, E-ISSN 2352-1791Artikkel i tidsskrift (Fagfellevurdert)
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