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  • 1. Airila, M. I.
    et al.
    Aho-Mantila, L.
    Brezinsek, S.
    Coad, J. P.
    Kirschner, A.
    Likonen, J.
    Matveev, D.
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Strachan, J. D.
    Widdowson, A.
    Wiesen, S.
    ERO modelling of local deposition of injected C-13 tracer at the outer divertor of JET2009Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T138, s. 014021-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The 2004 tracer experiment of JET with the injection of (CH4)-C-13 into H-mode plasma at the outer divertor has been modelled with the Monte Carlo impurity transport code ERO. EDGE2D solutions for inter-ELM and ELM-peak phases were used as plasma backgrounds. Local two-dimensional (2D) deposition patterns at the vertical outer divertor target plate were obtained for comparison with post-mortem surface analyses. ERO also provides emission profiles for comparison with radially resolved spectroscopic measurements. Modelling indicates that enhanced re-erosion of deposited carbon layers is essential in explaining the amount of local deposition. Assuming negligible effective sticking of hydrocarbons, the measured local deposition of 20-34% is reproduced if re-erosion of deposits is enhanced by a factor of 2.5-7 compared to graphite erosion. If deposits are treated like the substrate, the modelled deposition is 55%. Deposition measurements at the shadowed area around injectors can be well explained by assuming negligible re-erosion but similar sticking behaviour there as on plasma-wetted surfaces.

  • 2.
    Akhmedov, Evgeny
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik.
    Frigerio, M.
    Duality in left-right symmetric seesaw2006Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T127, s. 59-61Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We perform a reconstruction of the mass matrix of heavy right-handed Majorana neutrinos in the framework of the left - right symmetric type I + II seesaw mechanism. An intriguing pairwise duality relation between different solutions is shown to exist.

  • 3. Alegre, Daniel
    et al.
    Bergsåker, Henric
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Bykov, Igor
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Gasior, Pawel
    Kubkowska, Monika
    Kowalska-Strzeciwilk, Ewa
    Petersson, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Tabares, Francisco L.
    Study of correlation of deuterium content in a-C:D dust induced by laser irradiation from the co-deposited surface with the grain size and velocity2014Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T161, s. 014010-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the study described here, the laser ablation method was applied to clean thick (40-60 m) a-C: D co-deposits on the ALT-II limiter blade from the TEXTOR tokamak, and at the same time to characterize the ejected particles formed during ablation and measure the amount of fuel carried by them. Ablation was accomplished by similar to 3.5 ns, 0.5 J Nd: YAG laser pulses in either vacuum or an O-2 atmosphere at different pressures. Fast camera tracking of the process provided an estimate of the population and velocity of up to 100ms(-1) for larger dust particles. In the same experiment, the dust particles were caught using ultra-light Si aerogel collectors placed in front of the ablation target. SEM analysis of aerogel surfaces verified the speed estimate, providing the trapped particles' size distribution and particle yield during ablation. The D/C atomic concentration ratio was measured with the 3HE ion beam nuclear reaction analysis method in deposited layers before ablation and with a micro-ion beam in individual particles on aerogel collectors. This indicated that most of the D was thermally released during ablation, leaving no more than 5% of its original amount in the particles. The effect of ablation conditions on the acceleration of ejected particles, their population, composition and D content is the main subject of this paper.

  • 4.
    Alexander, Gerianne
    et al.
    Texas A&M Univ, Dept Psychol & Brain Sci, College Stn, TX USA..
    Allen, Roland E.
    Texas A&M Univ, Dept Phys & Astron, College Stn, TX 77843 USA..
    Atala, Anthony
    Wake Forest Inst Regenerat Med, 391 Technol Way, Winston Salem, NC 27157 USA..
    Bowen, Warwick P.
    Univ Queensland, Sch Math & Phys, St Lucia, Qld 4072, Australia.;Univ Queensland, Australian Ctr Engn Quantum Syst, St Lucia, Qld 4072, Australia..
    Coley, Alan A.
    Dalhousie Univ, Dept Math & Stat, Halifax, NS B3H 4R2, Canada..
    Goodenough, John B.
    Univ Texas Austin, Cockrell Inst, Walker Dept Mech Engn, Austin, TX 78712 USA..
    Katsnelson, Mikhail, I
    Radboud Univ Nijmegen, Inst Mol & Mat, NL-6525 AJ Nijmegen, Netherlands..
    Koonin, Eugene, V
    Natl Lib Med, Natl Ctr Biotechnol Informat, Bethesda, MD 20894 USA..
    Krenn, Mario
    Austrian Acad Sci, Inst Quantum Opt & Quantum Informat IQOQI, Boltzmanngasse 3, A-1090 Vienna, Austria.;Univ Toronto, Dept Chem, Toronto, ON, Canada..
    Madsen, Lars S.
    Univ Queensland, Australian Ctr Engn Quantum Syst, St Lucia, Qld 4072, Australia..
    Månsson, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik.
    Mauranyapin, Nicolas P.
    Univ Queensland, Sch Math & Phys, St Lucia, Qld 4072, Australia..
    Melvin, Art, I
    Austrian Acad Sci, Inst Quantum Opt & Quantum Informat IQOQI, Boltzmanngasse 3, A-1090 Vienna, Austria.;Univ Vienna, Fac Phys, Vienna Ctr Quantum Sci & Technol VCQ, Boltzmanngasse 5, A-1090 Vienna, Austria..
    Rasel, Ernst
    Inst Quantenopt, Welfengarten 1, D-30167 Hannover, Germany.;Leibnitz Univ Hannover, QUEST LFS DLR Inst Satellite Geodesy & Inertial S, Welfengarten 1, D-30167 Hannover, Germany..
    Reichl, Linda E.
    Univ Texas Austin, Ctr Complex Quantum Syst, Austin, TX 78712 USA.;Univ Texas Austin, Dept Phys, Austin, TX 78712 USA..
    Yampolskiy, Roman
    Univ Louisville, Duthie Ctr Engn, Dept Comp Engn & Comp Sci, Louisville, KY 40292 USA..
    Yasskin, Philip B.
    Texas A&M Univ, Dept Math, College Stn, TX 77843 USA..
    Zeilinger, Anton
    Austrian Acad Sci, Inst Quantum Opt & Quantum Informat IQOQI, Boltzmanngasse 3, A-1090 Vienna, Austria.;Univ Vienna, Fac Phys, Vienna Ctr Quantum Sci & Technol VCQ, Boltzmanngasse 5, A-1090 Vienna, Austria..
    Lidstrom, Suzy
    Texas A&M Univ, Dept Phys & Astron, College Stn, TX 77843 USA..
    The sounds of science-a symphony for many instruments and voices2020Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 95, nr 6, artikkel-id 062501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sounds of Science is the first movement of a symphony for many (scientific) instruments and voices, united in celebration of the frontiers of science and intended for a general audience. John Goodenough, the maestro who transformed energy usage and technology through the invention of the lithium-ion battery, opens the programme, reflecting on the ultimate limits of battery technology. This applied theme continues through the subsequent pieces on energy-related topics-the sodium-ion battery and artificial fuels, by Martin Mansson-and the ultimate challenge for 3D printing, the eventual production of life, by Anthony Atala. A passage by Gerianne Alexander follows, contemplating a related issue: How might an artificially produced human being behave? Next comes a consideration of consciousness and free will by Roland Allen and Suzy Lidstrom. Further voices and new instruments enter as Warwick Bowen, Nicolas Mauranyapin and Lars Madsen discuss whether dynamical processes of single molecules might be observed in their native state. The exploitation of chaos in science and technology, applications of Bose-Einstein condensates and the significance of entropy follow in pieces by Linda Reichl, Ernst Rasel and Roland Allen, respectively. Mikhail Katsnelson and Eugene Koonin then discuss the potential generalisation of thermodynamic concepts in the context of biological evolution. Entering with the music of the cosmos, Philip Yasskin discusses whether we might be able to observe torsion in the geometry of the Universe. The crescendo comes with the crisis of singularities, their nature and whether they can be resolved through quantum effects, in the composition of Alan Coley. The climax is Mario Krenn, Art Melvin and Anton Zeilinger's consideration of how computer code can be autonomously surprising and creative. In a harmonious counterpoint, his 'Guidelines for considering AIs as coauthors', Roman Yampolskiy concludes that code is not yet able to take responsibility for coauthoring a paper. An interlude summarises a speech by Zdenek Papousek. In a subsequent movement, new themes emerge as we seek to comprehend how far we have travelled along the path to understanding, and speculate on where new physics might arise. Who would have imagined, 100 years ago, a global society permeated by smartphones and scientific instruments so sophisticated that genes can be modified and gravitational waves detected?

  • 5. Al-Zoubi, Noura
    et al.
    Li, Xiaoqing
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Egenskaper.
    Schönecker, Stephan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Egenskaper.
    Johansson, Börje
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Egenskaper. Uppsala University, Uppsala, Sweden .
    Vitos, Levente
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Egenskaper. Uppsala University, Uppsala, Sweden; Wigner Research Center for Physics, Budapest, Hungary .
    Influence of manganese on the bulk properties of Fe-Cr-Mn alloys: a first-principles study2014Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 89, nr 12, s. 125702-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate the effect of manganese on lattice stability and magnetic moments of paramagnetic Fe-Cr-Mn steel alloys along the Bain path connecting the body-centered cubic (bcc) and face-centered cubic (fcc) structures. The calculations are carried out using the ab initio exact muffin-tin orbital method, in combination with the coherent potential approximation, and the paramagnetic phase is modeled by the disordered local magnetic moment scheme. For all Fe-Cr-Mn alloys considered here, the local magnetic moments on Fe atoms have the minimum values for the fcc structure and the maximum values for the bcc structure, whereas the local magnetic moments on Mn have almost the same value along the constant-volume Bain path. Our results show that Mn addition to paramagnetic Fe-Cr solid solution stabilizes the bcc structure. However, when considering the paramagnetic fcc phase relative to the ferromagnetic bcc ground state, then Mn turns out to be a clear fcc stabilizer, in line with observations.

  • 6. Antoni, V.
    et al.
    Drake, James R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Spada, E.
    Spolaore, M.
    Vianello, N.
    Bergsåker, Henric
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Cavazzana, R.
    Cecconello, Marco
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Martines, E.
    Serianni, G.
    Coherent structures and anomalous transport in reversed field pinch plasmas2006Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T122, s. 1-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The results leading to the identification of coherent structures emerging from the background turbulence in the edge region of the reversed field pinch experiments EXTRAP-T2R and RFX are reviewed. These structures have traits of vortices in velocity field and blobs in density, and the reconstruction of their spatial structure and of their time evolution is discussed focusing on the analysis tools applied. The role of these structures in the particle anomalous transport is addressed, showing that their collisions can contribute up to 50% the total particle losses. This process is shown to be responsible for bursts in particle flux and it is found to set a characteristic collision time, which is in agreement with the statistical properties of laminar times for particle flux bursts.

  • 7. Beal, J.
    et al.
    Bergsåker, Henric
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Bykov, Igor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Elevant, Thomas
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Frassinetti, Lorenzo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Garcia-Carrasco, Alvaro
    Hellsten, Torbjörn
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Ivanova, Darya
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Johnson, Thomas
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Menmuir, Sheena
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Petersson, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Rachlew, Elisabeth
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Ström, Petter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Tholerus, Emmi
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Weckmann, Armin
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Zychor, I.
    Deposition in the inner and outer corners of the JET divertor with carbon wall and metallic ITER-like wall2016Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T167, artikkel-id 014052Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rotating collectors and quartz microbalances (QMBs) are used in JET to provide time-dependent measurements of erosion and deposition. Rotation of collector discs behind apertures allows recording of the long term evolution of deposition. QMBs measure mass change via the frequency deviations of vibrating quartz crystals. These diagnostics are used to investigate erosion/deposition during JET-C carbon operation and JET-ILW (ITER-like wall) beryllium/tungsten operation. A simple geometrical model utilising experimental data is used to model the time-dependent collector deposition profiles, demonstrating good qualitative agreement with experimental results. Overall, the JET-ILW collector deposition is reduced by an order of magnitude relative to JET-C, with beryllium replacing carbon as the dominant deposit. However, contrary to JET-C, in JET-ILW there is more deposition on the outer collector than the inner. This reversal of deposition asymmetry is investigated using an analysis of QMB data and is attributed to the different chemical properties of carbon and beryllium.

  • 8. Behringer, Hans
    et al.
    Eichhorn, Ralf
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Wallin, Stefan
    Dynamics of biomolecular processes PREFACE2013Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 87, nr 5, s. 058501-Artikkel i tidsskrift (Annet vitenskapelig)
  • 9.
    Bennett, Kochise
    et al.
    Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA.;Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA..
    Zhang, Yu
    Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA..
    Kowalewski, Markus
    Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA..
    Hua, Weijie
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA.;KTH Royal Inst Technol, Sch Biotechnol, Dept Theoret Chem & Biol, S-10691 Stockholm, Sweden..
    Mukamel, Shaul
    Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA.;Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA.;Freiburg Inst Adv Studies FRIAS, Freiburg, Germany..
    Multidimensional resonant nonlinear spectroscopy with coherent broadband x-ray pulses2016Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T169, artikkel-id 014002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    New x-ray free electron laser (XFEL) and high harmonic generation (HHG) light sources are capable of generating short and intense pulses that make x-ray nonlinear spectroscopy possible. Multidimensional spectroscopic techniques, which have long been used in the nuclear magnetic resonance, infrared, and optical regimes to probe the electronic structure and nuclear dynamics of molecules by sequences of short pulses with variable delays, can thus be extended to the attosecond x-ray regime. This opens up the possibility of probing core-electronic structure and couplings, the real-time tracking of impulsively created valence-electronic wavepackets and electronic coherences, and monitoring ultrafast processes such as nonadiabatic electron-nuclear dynamics near conical-intersection crossings. We survey various possible types of multidimensional x-ray spectroscopy techniques and demonstrate the novel information they can provide about molecules.

  • 10.
    Bergsåker, B. Henric M.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. EUROfusion Consortium, Culham Science Centre, JET, Abingdon, United Kingdom.
    Bykov, Igor
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. EUROfusion Consortium, Culham Science Centre, JET, Abingdon, United Kingdom.
    Zhou, Yushan
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. EUROfusion Consortium, Culham Science Centre, JET, Abingdon, United Kingdom.
    Petersson, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. EUROfusion Consortium, Culham Science Centre, JET, Abingdon, United Kingdom.
    Possnert, G.
    Likonen, J.
    Pettersson, J.
    Koivuranta, S.
    Widdowson, A. M.
    Deep deuterium retention and Be/W mixing at tungsten coated surfaces in the JET divertor2016Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T167, artikkel-id 014061Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Surface samples from a full poloidal set of divertor tiles exposed in JET through operations 2010-2012 with ITER-like wall have been investigated using SEM, SIMS, ICP-AES analysis and micro beam nuclear reaction analysis (μ-NRA). Deposition of Be and retention of D is microscopically inhomogeneous. With careful overlaying of μ-NRA elemental maps with SEM images, it is possible to separate surface roughness effects from depth profiles at microscopically flat surface regions, without pits. With (3He, p) μ-NRA at 3-5 MeV beam energy the accessible depth for D analysis in W is about 9 μm, sufficient to access the W/Mo and Mo/W interfaces in the coatings and beyond, while for Be in W it is about 6 μm. In these conditions, at all plasma wetted surfaces, D was found throughout the whole accessible depth at concentrations in the range 0.2-0.7 at% in W. Deuterium was found to be preferentially trapped at the W/Mo and Mo/W interfaces. Comparison is made with SIMS profiling, which also shows significant D trapping at the W/Mo interface. Mixing of Be and W occurs mainly in deposited layers.

  • 11.
    Bergsåker, Henric
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Bykov, Igor
    Zhou, Yushan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Petersson, Per
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Possnert, G
    Likonen, J
    Pettersson, J
    Koivuranta, S
    Widdowson, A.M.
    contributors, JET
    Deep deuterium retention and Be/W mixingat tungsten coated surfaces in the JETdivertor2016Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Surface samples from a full poloidal set of divertor tiles exposed in JET through operations2010–2012 with ITER-like wall have been investigated using SEM, SIMS, ICP-AES analysisand micro beam nuclear reaction analysis (μ-NRA). Deposition of Be and retention of D ismicroscopically inhomogeneous. With careful overlaying of μ-NRA elemental maps with SEMimages, it is possible to separate surface roughness effects from depth profiles at microscopicallyflat surface regions, without pits. With (3He, p) μ-NRA at 3–5 MeV beam energy the accessibledepth for D analysis in W is about 9 μm, sufficient to access the W/Mo and Mo/W interfaces inthe coatings and beyond, while for Be in W it is about 6 μm. In these conditions, at all plasmawetted surfaces, D was found throughout the whole accessible depth at concentrations in therange 0.2–0.7 at% in W. Deuterium was found to be preferentially trapped at the W/Mo andMo/W interfaces. Comparison is made with SIMS profiling, which also shows significant Dtrapping at the W/Mo interface. Mixing of Be and W occurs mainly in deposited layers.

  • 12.
    Björk, Gunnar
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvantelektronik och -optik, QEO.
    Grassl, Markus
    de la Hoz, Pablo
    Leuchs, Gerd
    Sanchez-Soto, Luis L.
    Stars of the quantum Universe: extremal constellations on the Poincare sphere2015Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 90, nr 10, artikkel-id 108008Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The characterization of the polarization properties of a quantum state requires the knowledge of the joint probability distribution of the Stokes variables. This amounts to assessing all the moments of these variables, which are aptly encoded in a multipole expansion of the density matrix. The cumulative distribution of these multipoles encapsulates in a handy manner the polarization content of the state. We work out the extremal states for that distribution, finding that SU(2) coherent states are maximal to any order, so they are the most polarized allowed by quantum theory. The converse case of pure states minimizing that distribution, which can be seen as the most quantum ones, is investigated for a diverse range of number of photons. Exploiting the Majorana representation, the problem appears to be closely related to distributing a number of points uniformly over the surface of the Poincare sphere.

  • 13.
    Björk, Gunnar
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvantelektronik och -optik, QEO.
    Man'ko, Margarita
    20th Central European Workshop on Quantum Optics Preface2014Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T160, s. 010301-Artikkel i tidsskrift (Fagfellevurdert)
  • 14.
    Björk, Gunnar
    et al.
    KTH, Tidigare Institutioner (före 2005), Mikroelektronik och informationsteknik, IMIT.
    Soderholm, J.
    Trifonov, A.
    Tsegaye, T.
    A theory of the relative phase and number difference of two quantized harmonic oscillators2002Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T102, s. 133-146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a comprehensive and self-consistent theory of relative-phase measurements and the associated Hermitian relative-phase operator of two harmonic oscillators. We find that since Nature does not favor any particular initial condition of the two oscillators, the relative-phase operator is not unique. We show that the relative-phase eigenstates; are maximally entangled. Therefore. most relative-phase operators lack a classical correspondence, even in the high-excitation limit. Furthermore, we find that the relative phase and the excitation number difference are noncommuting, noncanonical observables and we derive a commutation relation.

  • 15.
    Blennow, Mattias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik.
    Edsjö, Joakim
    Ohlsson, Tommy
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Neutrinos from WIMP annihilations in the Sun including neutrino oscillations2006Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T127, s. 19-21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The prospects for detecting neutrinos from the Sun arising from dark matter annihilations in the core of the Sun are reviewed. Emphasis is placed on new work investigating the effects of neutrino oscillations on the expected neutrino fluxes.

    Fulltekst (pdf)
    fulltext
  • 16.
    Blom, Hans
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Bates, Mark
    Nanoscopy-imaging life at the nanoscale: a Nobel Prize achievement with a bright future2015Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 90, nr 10, artikkel-id 108010Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A grand scientific prize was awarded last year to three pioneering scientists, for their discovery and development of molecular 'ON-OFF' switching which, when combined with optical imaging, can be used to see the previously invisible with light microscopy. The Royal Swedish Academy of Science announced on October 8th their decision and explained that this achievement-rooted in physics and applied in biology and medicine-was awarded with the Nobel Prize in Chemistry for controlling fluorescent molecules to create images of specimens smaller than anything previously observed with light. The story of how this noble switch in optical microscopy was achieved and how it was engineered to visualize life at the nanoscale is highlighted in this invited comment.

  • 17. Borodkina, I.
    et al.
    Borodin, D.
    Brezinsek, S.
    Tsvetkov, I. V.
    Kurnaev, V. A.
    Guillemaut, C.
    Maslov, M.
    Frassinetti, Lorenzo
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Intra-ELM tungsten sputtering in JET ITER-like wall: analytical studies of Be impurity and ELM type influence2017Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, artikkel-id 014065Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The W source strength in JET H-mode discharges depends on the W sputtering in the inter and the intra-ELM phase due to impinging hydrogenic ions (D or H) and impurities (mainly Be). The analytical approach for interpretation of the Langmuir probe measurements is applied to model the ELM ion parallel transport and the W sputtering flux in intra-ELM and inter-ELM conditions in JET-ITER-like wall (ILW) hydrogen and deuterium plasmas. The impact of the Be ion charge and the Be concentration in the impinging ion flux on the W sputtering was estimated. Be2+ concentrations of 0.5% and 1% in the impinging ion flux increases the W sputtering fluence per ELM by 20%-30% and 35%-55% correspondingly with respect to pure deuterium plasma; the charge state of Be ions has no substantial effect on W sputtering in the intra-ELM phase. The analysis of JET ELMy H-mode discharges in hydrogen with different types of ELMs is presented. The W sputtering source under inter-and intra-ELM conditions is estimated using the analytical approach and validated by optical emission spectroscopy in these discharges. The intra-ELM W sputtering flux increases 2-4 times in comparison to the inter-ELM flux.

  • 18. Boström, M.
    et al.
    Thiyam, Priyadarshini
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Persson, C.
    Parsons, D. F.
    Buhmann, S. Y.
    Brevik, I.
    Sernelius, Bo E.
    Non-perturbative theory of dispersion interactions2015Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 90, nr 3, artikkel-id 035405Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Some open questions exist with fluctuation-induced forces between extended dipoles. Conventional intuition derives from large-separation perturbative approximations to dispersion force theory. Here, we present a full non-perturbative theory. In addition, we discuss how one can take into account finite dipole size corrections. It is of fundamental value to investigate the limits of validity of the perturbative dispersion force theory.

  • 19.
    Brenning, Nils
    et al.
    KTH, Tidigare Institutioner (före 2005), Alfvénlaboratoriet.
    Fälthammar, Carl-Gunne
    KTH, Tidigare Institutioner (före 2005), Alfvénlaboratoriet.
    Dynamic trapping and skidding of dense plasma clouds2004Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 70, nr 03-feb, s. 153-156Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate the possibility that the mechanism dynamic trapping can play a role in decoupling dense plasma clouds injected in a thinner ambient plasma, by establishing strong magnetic-field-aligned electric fields in the vicinity or in the edge of the cloud. Dynamic trapping has previously been shown to allow such fields to be established and maintained on the time scale of ion motion, also for arbitrarily low current densities. A model is presented of how such fields could arise and decouple injected plasma clouds, a mechanism which we call dynamic decoupling. A dimensionless parameter. the dynamic decoupling factor F-DD, is derived which gives an estimate of the importance of the process. One possible application is the CRRES ionospheric injection experiments where anomalous skidding has recently been reported. However. the dynamic decoupling mechanism might also play a role in naturally occurring situations, e.g. the impulsive penetration of plasmoids from the solar wind into the Earth's magnetosphere.

  • 20. Brezinsek, S.
    et al.
    Bergsåker, Henric
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Bykov, Igor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Elevant, Thomas
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Frassinetti, Lorenzo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Garcia-Carrasco, Alvaro
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Hellsten, Torbjörn
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Ivanova, Darya
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Johnson, Thomas
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Menmuir, Sheena
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Petersson, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Rachlew, Elisabeth
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Ström, Petter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Tholerus, Emmi
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Weckmann, Armin
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Zychor, I.
    et al.,
    Characterisation of the deuterium recycling at the W divertor target plates in JET during steady-state plasma conditions and ELMs2016Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T167, artikkel-id 014076Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Experiments in the JET tokamak equipped with the ITER-like wall (ILW) revealed that the inner and outer target plate at the location of the strike points represent after one year of operation intact tungsten (W) surfaces without any beryllium (Be) surface coverage. The dynamics of near-surface retention, implantation, desorption and recycling of deuterium (D) in the divertor of plasma discharges are determined by W target plates. As the W plasma-facing components (PFCs) are not actively cooled, the surface temperature (T-surface) is increasing with plasma exposure, varying the balance between these processes in addition to the impinging deuteron fluxes and energies. The dynamic behaviour on a slow time scale of seconds was quantified in a series of identical L-mode discharges (JET Pulse Number (JPN)#81938-73) by intra-shot gas analysis providing the reduction of deuterium retention in W PFCs by 1/3 at a base temperature (T-base) range at the outer target plate between 65 degrees C and 150 degrees C equivalent to a T-surface span of 150 degrees C and 420 degrees C. The associated recycling and molecular D desorption during the discharge varies only at lowest temperatures moderately, whereas desorption between discharges rises significantly with increasing T-base. The retention measurements represent the sum of inner and outer divertor interaction at comparable T-surface. The dynamic behaviour on a fast time scale of ms was studied in a series of identical H-mode discharges (JPN #83623-83974) and coherent edge-localized mode (ELM) averaging. High energetic ELMs of about 3 keV are impacting on the W PFCs with fluxes of 3 x 10(23) D+ s(-1) m(-2) which is about four times higher than inter-ELM ion fluxes with an impact energy of about E-im = 200 eV. This intra-ELM ion flux is associated with a high heat flux of about 60 MW m(-2) to the outer target plate which causes T-surface rise by Delta T = 100 K per ELM covering finally the range between 160 degrees C and 1400 degrees C during the flat-top phase. ELM-induced desorption from saturated near-surface implantation regions as well as deep ELM-induced deuterium implantation areas under varying baseline temperature takes place. Subsequent refuelling by intra-ELM deuteron fluxes occurs and a complex interplay between deuterium fuelling and desorption can be observed in the temporal ELM footprint of the surface temperature (IR thermography), the impinging deuteron flux (Langmuir probes), and the Balmer radiation (emission spectroscopy) as representative for the deuterium recycling flux. In contrast to JET-C, a pronounced second peak, similar or equal to 8 ms delayed with respect to the initial ELM crash, in the D-alpha radiation and the ion flux has been observed. The peak can be related to desorption of implanted energetic intra-ELM D+ diffusing to the W surface, and performing local recycling.

  • 21. Brezinsek, Sebastijan
    et al.
    Wirtz, Marius
    Dorrow-Gesprach, Daniel
    Loewenhoff, Thorsten
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    16th International Conference on Plasma-Facing Materials and Components for Fusion Applications2017Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, artikkel-id 010201Artikkel i tidsskrift (Fagfellevurdert)
  • 22.
    Bäck, Torbjörn
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Cederwall, Bo
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Moradi, Farnaz Ghazi
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Johnson, Arne
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Wadsworth, R.
    The B(E2;0(gs)(+) -> 2(+)) systematics of Sn and Te isotopes in light of data in the light Sn region including a recent measurement in Te-108 using the combined recoil-decay-tagging-recoil-distance Doppler technique2012Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T150, s. 014003-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An experimental technique combining the well-established alpha/p-decay-recoil-tagging method with a differential plunger has recently been successful in producing results in the neutron-deficient region near Sn-100. This experimental technique is briefly presented here and the result of a recent measurement for Te-108 is put in the context of the systematics of B(E-2) values for the Te and Sn isotopic chains. New state-of-the-art shell-model calculations are presented for the Sn data, and possible explanations for the unusually large B(E-2) values for the Sn isotopes near the N = 50 shell closure are given.

  • 23.
    Bäcklund, Anna
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik.
    Bengtsson, Ingemar
    Four remarks on spin coherent states2014Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T163Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We discuss how to recognize the constellations seen in the Majorana representation of quantum states. Then we give explicit formulae for the metric and symplectic form on SU (2) orbits containing general number states. Their metric and symplectic areas differ unless the states are coherent. Finally we discuss some patterns that arise from the Lieb-Solovej map, and for dimensions up to nine we find the location of those states that maximize the Wehrl-Lieb entropy.

  • 24.
    Carlsund-Levin, Christina
    et al.
    KTH, Tidigare Institutioner (före 2005), Numerisk analys och datalogi, NADA.
    Elander, N.
    Nunez, A.
    Scrinzi, A.
    An exterior complex rotated coupled channel description of predissociation in diatomic molecules applied to a model of the four lowest (2)Sigma(+)-states in CaH2002Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 65, nr 4, s. 306-322Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The exterior complex rotated Coupled-Channel formulation of potential scattering makes it possible to calculate energies and widths for a non-adiabatic model of a diatomic molecule or quasimolecule, The structure and decay pattern of a diatomic system is in this way described in a non-perturbative way. In this contribution we use the non-adiabatic form of an empirically derived potential energy curve matrix, previously used by Martin, J. Chem. Phys. 88, 1997 (1988) [1], for the four lowest (2)Sigma(+)-states of the CaH radical to demonstrate how one can calculate term positions as well as non-radiative decay widths in a realistic case for a large range of rovibronic levels. The differences between the previously derived Born-Oppenheimer term values [1] and the present non-adiabatic results are discussed and compared with previous work.

  • 25. Catarino, N.
    et al.
    Widdowson, A.
    Baron-Wiechec, A.
    Coad, J. P.
    Heinola, K.
    Rubel, Marek
    KTH.
    Alves, E.
    Time-resolved deposition in the remote region of the JET-ILW divertor: measurements and modelling2017Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, artikkel-id 014059Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One crucial requirement for the development of fusion power is to know where, and how much, impurities collect in the machine, and how much of the fuelling isotope tritium will be trapped therein. The most relevant information on this issue comes from the operation of the Joint European Tokamak (JET), which is the world's largest operating tokamak and has the same interior plasma-facing materials as the next step machine, ITER. Much of the information gained so far has been from post-mortem analysis of samples collected after whole campaigns involving varied types of operation. This paper describes time-resolved measurements of the deposition rate using rotating collectors (RC) placed in remote areas of the JET divertor during the 2013-2014 campaign with the ITER-like Wall (ILW). These techniques allow the effects of different types of operation to be distinguished. Rotating collectors made of silicon discs housed behind an aperture are exposed to the plasma. Each time the magnetic field coils are ramped up for a discharge the disc rotates, providing a linear relationship between the exposed region and the discharge number. Post-mortem ion beam analyses provide information on the deposit composition as a function of the discharge number. The results show that the Be deposition average for the RC in the corners of the inner and outer divertor are 4.9 x 10(16) cm(-2) and 1.8 x 10(17) cm(-2), respectively, accumulated over an average of similar to 25 pulses. Data from the rotating collector below Tile 5 in the central region of divertor indicate a Be deposition rate of 9.3 x 10(15) cm(-2), per similar to 25 pulses.

  • 26.
    Catarino, N.
    et al.
    Univ Lisbon, Inst Super Tecn, IPFN, P-1049001 Lisbon, Portugal..
    Widdowson, A.
    Culham Ctr Fus Energy, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England..
    Baron-Wiechec, A.
    Culham Ctr Fus Energy, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England..
    Coad, J. P.
    Culham Ctr Fus Energy, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England..
    Heinola, K.
    Univ Helsinki, POB 64, FI-00560 Helsinki, Finland.;IAEA, Div Phys & Chem Sci, Nucl Data Sect, POB 100, A-1400 Vienna, Austria..
    Rubel, Marek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Barradas, N. P.
    Univ Lisbon, Inst Super Tecn, IPFN, P-1049001 Lisbon, Portugal.;Univ Lisbon, Inst Super Tecn, C2TN, EN 10, P-2686953 Sacavem, Portugal..
    Alves, E.
    Univ Lisbon, Inst Super Tecn, IPFN, P-1049001 Lisbon, Portugal..
    Deposition in the tungsten divertor during the 2011-2016 campaigns in JET with ITER-like wall2020Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T171, nr 1, artikkel-id 014044Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A build-up of co-deposits in remote areas of the divertor can contribute significantly to the overall fuel retention. The control of plasma-material interactions via the study and understanding of erosion-deposition of PFCs provides vital information for the efficient future operation of ITER. The major aim of this work is to reveal details of beryllium deposition and fuel (deuterium) retention on divertor plasma-facing components removed from the JET ITER-Like Wall divertor after cumulative exposure during the first two (ILW-1+2) and all three (ILW-1+2+3) campaigns. Ion beam analysis techniques such as Rutherford backscattering spectrometry, nuclear reaction analysis and proton induced x-ray emission have been extensively used for post-mortem analyses of selected tiles from JET following each campaign and can provide relevant information on plasma-surface interactions like tungsten erosion, beryllium deposition and plasma fuel retention with divertor tiles via implantation or co-deposition. The studied divertor tiles represent a unique set of samples, which have been exposed to plasmas since the beginning of the JET-ILW operation for three successive plasma campaigns. This is a comprehensive comparison of divertor components after these operation periods. The results presented summarise deposition and fuel retention on Tiles 4 (inner base) and 6 (outer base). Although the deposition pattern is similar to that determined after individual campaigns, D retention is not a cumulative process and is determined mainly by the last campaign, and the total Be deposit after the 3 campaigns (i.e. data 1+2+3=tile exposed 2011-2016) is less than the sum of the deposits after each individual campaign (sum 1+2+3) for Tile 4 but greater for Tile 6.

  • 27.
    Cecconello, Marco
    et al.
    KTH, Tidigare Institutioner (före 2005), Alfvénlaboratoriet.
    Malmberg, Jenny-Ann
    KTH, Tidigare Institutioner (före 2005), Alfvénlaboratoriet.
    Sallander, Eva
    KTH, Tidigare Institutioner (före 2005), Alfvénlaboratoriet.
    Drake, Drake James
    KTH, Tidigare Institutioner (före 2005), Alfvénlaboratoriet.
    Self-organisation and intermittent coherent oscillations in the EXTRAP T2 reversed field pinch2002Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 65, nr 1, s. 69-75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many reversed-field pinch (RFP) experiments exhibit a coherent oscillatory behaviour that is characteristic of discrete dynamo events and is associated with intermittent current profile self-organisation phenomena. However, in the vast majority of the discharges in the resistive shell RFP experiment EXTRAP T2, the dynamo activity does not show global, coherent oscillatory behaviour, The internally resonant tearing modes are phase-aligned and wall-locked resulting in a large localised magnetic perturbation. Equilibrium and plasma parameters have a level of high frequency fluctuations but the average values are quasi-steady. For some discharges, however, the equilibrium parameters exhibit the oscillatory behaviour characteristic of the discrete dynamo events. For these discharges, the trend observed in the tearing mode spectra, associated with the onset of the discrete relaxation event behaviour, is a relative higher amplitude of m = 0 mode activity and relative lower amplitude of the m = 1 mode activity compared with their average values. Global plasma parameters and model profile calculations for sample discharges representing the two types of relaxation dynamics are presented.

  • 28.
    Cederwall, Bo
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    NCNP 2011: Nordic Conference on Nuclear Physics 2011 (Stockholm, Sweden, 13-17 June 2011)2012Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T150, s. 010101-Artikkel i tidsskrift (Annet vitenskapelig)
  • 29. Coad, J. P.
    et al.
    Alves, E.
    Barradas, N. P.
    Baron-Wiechec, A.
    Catarino, N.
    Heinola, K.
    Likonen, J.
    Mayer, M.
    Matthews, G. F.
    Petersson, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Widdowson, A.
    Surface analysis of tiles and samples exposed to the first JET campaigns with the ITER-like wall2014Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T159, s. 014012-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports on the first post-mortem analyses of tiles removed from JET after the first campaigns with the ITER-like wall (ILW) during 2011-12 [1]. Tiles from the divertor have been analysed by ion beam analysis techniques and by secondary ion mass spectrometry to determine the amount of beryllium deposition and deuterium retention in the tiles exposed to the scrape-off layer. Films 10-20 mu m thick were present at the top of tile 1, but only very thin films (<1 mu m) were found in the shadowed areas and on other divertor tiles. The total amount of Be found in the divertor following the ILW campaign was a factor of similar to 9 less than the material deposited in the 2007-09 carbon campaign, after allowing for the longer operations in 2007-09.

  • 30. Coad, J. P.
    et al.
    Gruenhagen, S.
    Hole, D. E.
    Hakola, A.
    Koivuranta, S.
    Likonen, J.
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Widdowson, A.
    Overview of JET post-mortem results following the 2007-9 operational period, and comparisons with previous campaigns2011Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T145, s. 014003-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In 2010, all the plasma-facing components were removed from JET so that the carbon-based surfaces could be replaced with beryllium (Be) or tungsten as part of the ITER-like wall (ILW) project. This gives unprecedented opportunities for post-mortem analyses of these plasma-facing surfaces; this paper reviews the data obtained so far and relates the information to studies of tiles removed during previous JET shutdowns. The general pattern of erosion/deposition at the JET divertor has been maintained, with deposition of impurities in the scrape-off layer (SOL) at the inner divertor and preferential removal of carbon and transport into the corner. However, the remaining films in the SOL contain very high Be/C ratios at the surface. The first measurements of erosion using a tile profiler have been completed, with up to 200 microns erosion being recorded at points on the inner wall guard limiters.

  • 31.
    Coburn, J.
    et al.
    ITER Org, Route Vinon Sur Verdon,CS 90 046, F-13067 St Paul Les Durance, France..
    Thorén, Emil
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Rymd- och plasmafysik.
    Pitts, R. A.
    ITER Org, Route Vinon Sur Verdon,CS 90 046, F-13067 St Paul Les Durance, France..
    Anand, H.
    ITER Org, Route Vinon Sur Verdon,CS 90 046, F-13067 St Paul Les Durance, France..
    Lehnen, M.
    ITER Org, Route Vinon Sur Verdon,CS 90 046, F-13067 St Paul Les Durance, France..
    Kos, L.
    Univ Ljubljana, LECAD Lab, Mech Engn, Ljubljana, Slovenia..
    Brank, M.
    Univ Ljubljana, LECAD Lab, Mech Engn, Ljubljana, Slovenia..
    Ratynskaia, Svetlana V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Rymd- och plasmafysik.
    Tolias, Panagiotis
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Rymd- och plasmafysik.
    First wall energy deposition during vertical displacement events on ITER2020Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T171, nr 1, artikkel-id 014076Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The beryllium (Be) first wall energy deposition and melt damage profiles resulting from the current quench phase of an unmitigated, 5 MA/1.8 T upward vertical displacement event for ITER are investigated. Time dependent 2D magnetic flux profiles are calculated with the DINA code and used as input for the SMITER 3D field line tracing software. 3D maps of the wetted area and perpendicular heat flux q(perpendicular to) show that the majority of the energy deposition occurs on the upper first wall panels #8 and #9 SMITER simulations predict q(perpendicular to,peak) approximate to 190 MW m(-2) on the surfaces of upper FWPs #8 and #9 at the end of the similar to 450 ms current quench. The surface heat flux maps generated by SMITER are used as input in the MEMOS-U code, which models Be melt formation and dynamics. Simulations reveal peak surface temperatures of similar to 2200 K, inward surface damage of similar to 0.5 mm in depth, and average melt velocities of similar to 2 m s(-1). Although VDEs are in principle the easiest disruptive instability to avoid, the analysis demonstrates that any non-mitigated events or intentional VDEs taking place during low I-p, early operational phases of ITER for the purposes of estimating disruption forces, must be kept to a low number.

  • 32. Coenen, J. W.
    et al.
    Matthews, G. F.
    Krieger, K.
    Iglesias, D.
    Bunting, P.
    Corre, Y.
    Silburn, S.
    Balboa, I.
    Bazylevs, B.
    Conway, N.
    Coffey, I.
    Dejarnac, R.
    Gauthier, E.
    Gaspar, J.
    Jachmich, S.
    Jepu, I.
    Makepeace, C.
    Scannell, R.
    Stamp, M.
    Petersson, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Pitts, R. A.
    Wiesen, S.
    Widdowson, A.
    Heinola, K.
    Baron-Wiechec, A.
    Transient induced tungsten melting at the Joint European Torus (JET)2017Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, artikkel-id 014013Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Melting is one of the major risks associated with tungsten (W) plasma-facing components (PFCs) in tokamaks like JET or ITER. These components are designed such that leading edges and hence excessive plasma heat loads deposited at near normal incidence are avoided. Due to the high stored energies in ITER discharges, shallow surface melting can occur under insufficiently mitigated plasma disruption and so-called edge localised modes-power load transients. A dedicated program was carried out at the JET to study the physics and consequences of W transient melting. Following initial exposures in 2013 (ILW-1) of a W-lamella with leading edge, new experiments have been performed on a sloped surface (15 degrees slope) during the 2015/2016 (ILW-3) campaign. This new experiment allows significantly improved infrared thermography measurements and thus resolved important issue of power loading in the context of the previous leading edge exposures. The new lamella was monitored by local diagnostics: spectroscopy, thermography and high-resolution photography in between discharges. No impact on the main plasma was observed despite a strong increase of the local W source consistent with evaporation. In contrast to the earlier exposure, no droplet emission was observed from the sloped surface. Topological modifications resulting from the melting are clearly visible between discharges on the photographic images. Melt damage can be clearly linked to the infrared measurements: the emissivity drops in zones where melting occurs. In comparison with the previous leading edge experiment, no runaway melt motion is observed, consistent with the hypothesis that the escape of thermionic electrons emitted from the melt zone is largely suppressed in this geometry, where the magnetic field intersects the surface at lower angles than in the case of perpendicular impact on a leading edge. Utilising both exposures allows us to further test the model of the forces driving melt motion that successfully reproduced the findings from the original leading edge exposure. Since the ILW-1 experiments, the exposed misaligned lamella has now been retrieved from the JET machine and post mortem analysis has been performed. No obvious mass loss is observed. Profilometry of the ILW-1 lamella shows the structure of the melt damage which is in line with the modell predictions thus allowing further model validation. Nuclear reaction analysis shows a tenfold reduction in surface deuterium concentration in the molten surface in comparison to the non-molten part of the lamella.

  • 33. Coreno, M.
    et al.
    Kivimaeki, A.
    de Simone, M.
    Garcia, E. Melero
    Vall-Llosera, G.
    Ruiz, J. Alvarez
    Rachlew, Elisabeth
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Atom- och molekylfysik.
    Stankiewicz, M.
    Vis-UV fluorescence studies of fragments resulting from the relaxation of molecular core hole states2007Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 76, nr 3, s. C90-C95Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The absorption of soft x-ray radiation induces neutral and ionic core hole states in molecules. The relaxation of such states typically leads to a multi-step process, at the end of which photons in the visible and UV range can also be emitted from fragments. In this paper, we present results on Balmer and Lyman emission that originates from excited H atoms produced at the K-edge of the water, ammonia and methane molecules. Dissociation pathways leading to fluorescence emission are discussed.

  • 34. Corre, Y.
    et al.
    Rachlew, Elisabeth
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Atom- och molekylfysik.
    Cecconello, M.
    Gravestijn, R. M.
    Hedqvist, A.
    Pegourie, B.
    Schunke, B.
    Stancalie, V.
    Radiated power and impurity concentrations in the EXTRAP-T2R reversed-field pinch2005Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 71, nr 5, s. 523-531Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A numerical and experimental study of the impurity concentration and radiation in the EXTRAP-T2R device is reported. The experimental setup consists of an 8-chord bolometer system providing the plasma radiated power and a vacuum-ultraviolet spectrometer providing information on the plasma impurity content. The plasma emissivity profile as measured by the bolometric system is peaked in the plasma centre. A one dimensional Onion Skin Collisional-Radiative model (OSCR) has been developed to compute the density and radiation distributions of the main impurities. The observed centrally peaked emissivity profile can be reproduced by OSCR simulations only if finite particle confinement time and charge-exchange processes between plasma impurities and neutral hydrogen are taken into account. The neutral hydrogen density profile is computed with a recycling code. Simulations show that recycling on metal first wall such as in EXTRAP-T2R (stainless steel vacuum vessel and molybdenum limiters) is compatible with a rather high neutral hydrogen density in the plasma centre. Assuming an impurity concentration of 10% for oxygen and 3% for carbon compared with the electron density, the OSCR calculation including lines and continuum emission reproduces about 60% of the total radiated power with a similarly centrally peaked emmissivity profile. The centrally peaked emissivity profile is due to low ionisation stages and strongly radiating species in the plasma core, mainly O4+ (Be-like) and C3+ (Li-like).

  • 35.
    Corre, Y.
    et al.
    CEA, Inst Res Fus Magnet Confinement, F-13108 St Paul Les Durance, France..
    Ratynskaia, Svetlana V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Rymd- och plasmafysik.
    Thorén, Emil
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Rymd- och plasmafysik.
    Tolias, Panagiotis
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Rymd- och plasmafysik.
    Tsitrone, E.
    CEA, Inst Res Fus Magnet Confinement, F-13108 St Paul Les Durance, France..
    Sustained W-melting experiments on actively cooled ITER-like plasma facing unit in WEST2021Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 96, nr 12, artikkel-id 124057Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The consequences of tungsten (W) melting on divertor lifetime and plasma operation are high priority issues for ITER. Sustained and controlled W-melting experiment has been achieved for the first time in WEST on a poloidal sharp leading edge of an actively cooled ITER-like plasma facing unit (PFU). A series of dedicated high power steady state plasma discharges were performed to reach the melting point of tungsten. The leading edge was exposed to a parallel heat flux of about 100 MW.m(-2) for up to 5 s providing a melt phase of about 2 s without noticeable impact of melting on plasma operation (radiated power and tungsten impurity content remained stable at constant input power) and no melt ejection were observed. The surface temperature of the MB was monitored by a high spatial resolution (0.1 mm/pixel) infrared camera viewing the melt zone from the top of the machine. The melting discharge was repeated three times resulting in about 6 s accumulated melting duration leading to material displacement from three similar pools. Cumulated on the overall sustained melting periods, this leads to excavation depth of about 230 mu m followed by a re-solidified tungsten bump of 200 mu m in the JxB direction.

  • 36. da Silva, A. F.
    et al.
    Pepe, I.
    Persson, Clas
    KTH, Tidigare Institutioner (före 2005), Materialvetenskap.
    de Almeida, J. S.
    Araujo, C. M.
    Ahuja, Rajeev
    Johansson, Börje
    KTH, Tidigare Institutioner (före 2005), Materialvetenskap.
    An, C. Y.
    Guo, J. H.
    Optical properties of oxide compounds PbO, SnO2 and TiO22004Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T109, s. 180-183Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The optical properties of the oxide compounds PbO and SnO2 have been investigated experimentally by transmission spectroscopy measurements and theoretically by a full-potential linearized augmented plane wave (FPLAPW) method. The dielectric functions of the rutile TiO2 has also been calculated. The calculated band-gap energies as well as the optical absorption were found to be in a very good qualitatively agreement with the experimental results.

  • 37.
    Dahlin, Jon-Erik
    et al.
    KTH, Tidigare Institutioner (före 2005), Alfvénlaboratoriet.
    Scheffel, Jan
    KTH, Tidigare Institutioner (före 2005), Alfvénlaboratoriet.
    Self-consistent zero-dimensional numerical simulation of a Magnetized Target Fusion Configuration2004Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 70, nr 5, s. 310-316Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A self-consistent zero-dimensional model of a Magnetized Target Fusion (MTF) configuration is presented. The plasma target is a Field Reversed Configuration (FRC). Model parameters were scanned using a Monte Carlo routine in order to determine an operating point that would correspond to reactor conditions. Albeit the model being intrinsically optimistic, the highest Q-values found only slightly exceed unity. The limited performance is due to the short dwell time of the liner, preventing a large portion of the fuel to burn.

  • 38. De Backer, A.
    et al.
    Sand, A.
    Ortiz, C. J.
    Domain, C.
    Olsson, Pär
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Reaktorfysik.
    Berthod, E.
    Becquart, C. S.
    Primary damage in tungsten using the binary collision approximation, molecular dynamic simulations and the density functional theory2016Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T167, artikkel-id 014018Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The damage produced by primary knock-on atoms (PKA) in W has been investigated from the threshold displacement energy (TDE) where it produces one self interstitial atom-vacancy pair to larger energies, up to 100 keV, where a large molten volume is formed. The TDE has been determined in different crystal directions using the Born-Oppenheimer density functional molecular dynamics (DFT-MD). A significant difference has been observed without and with the semi-core electrons. Classical MD has been used with two different empirical potentials characterized as 'soft' and 'hard' to obtain statistics on TDEs. Cascades of larger energy have been calculated, with these potentials, using a model that accounts for electronic losses (Sand et al 2013 Europhys. Lett. 103 46003). Two other sets of cascades have been produced using the binary collision approximation (BCA): a Monte Carlo BCA using SDTrimSP (Eckstein et al 2011 SDTrimSP: Version 5.00. Report IPP 12/8) (similar to SRIM www.srim.org) and MARLOWE (RSICC Home Page. (https://rsicc.ornl.gov/codes/psr/psr1/psr-137.html) (accessed May, 2014)). The comparison of these sets of cascades gave a recombination distance equal to 12 angstrom which is significantly larger from the one we reported in Hou et al (2010 J. Nucl. Mater. 403 89) because, here, we used bulk cascades rather than surface cascades which produce more defects (Stoller 2002 J. Nucl. Mater. 307 935, Nordlund et al 1999 Nature 398 49). Investigations on the defect clustering aspect showed that the difference between BCA and MD cascades is considerably reduced after the annealing of the cascade debris at 473 K using our Object Kinetic Monte Carlo model, LAKIMOCA.

  • 39. de la Hoz, P.
    et al.
    Björk, Gunnar
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvantelektronik och -optik, QEO.
    de Guise, H.
    Klimov, A. B.
    Leuchs, G.
    Sanchez-Soto, L. L.
    Classical polarization multipoles: paraxial versus nonparaxial2015Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 90, nr 7, artikkel-id 074030Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We discuss the polarization of paraxial and nonparaxial classical light fields by resorting to a multipole expansion of the corresponding polarization matrix. It turns out that only a dipolar term contributes when one considers SU(2) (paraxial) or SU(3) (nonparaxial) as fundamental symmetries. In this latter case, one can alternatively expand in SU(2) multipoles, and then both a dipolar and a quadrupolar component contribute, which explains the richer structure of this nonparaxial instance. These multipoles uniquely determine Wigner functions, in terms of which we examine some intriguing hallmarks arising in this classical scenario.

  • 40.
    Dittrich, Laura
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Petersson, Per
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Rubel, Marek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Tran, Tuan Thien
    Uppsala Univ, Dept Phys & Astron, S-75120 Uppsala, Sweden..
    Widdowson, Anna
    UK Atom Energy Author, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England..
    Jepu, Ionut
    UK Atom Energy Author, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.;Natl Inst Laser Plasma & Radiat Phys, Magurele 077125, Romania..
    Porosnicu, Corneliu
    Natl Inst Laser Plasma & Radiat Phys, Magurele 077125, Romania..
    Alves, Eduardo
    Univ Lisbon, Inst Super Tecn, IPFN, P-1049001 Lisbon, Portugal..
    Catarino, Norberto
    Univ Lisbon, Inst Super Tecn, IPFN, P-1049001 Lisbon, Portugal..
    Fuel retention and erosion-deposition on inner wall cladding tiles in JET-ILW2021Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 96, nr 12, artikkel-id 124071Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The morphology of beryllium coatings on the Inconel inner wall cladding tiles after JET-ILW campaigns was determined. The focus was on: (i) fuel retention and its share in the overall fuel inventory; (ii) the change of the layer structure and composition. The study is motivated in the view of planned D-T operation in JET. Four tiles were examined: the initial not exposed; one exposed to two campaigns (ILW1-2) and two facing the plasma during ILW1-3. As determined with ion beam and microscopy methods, the initial Be layer (9.0 mu m thick) contained up to 4-5 at.% of impurities, mainly H, O, C, Ni. In the exposed tiles, the impurity content increases to 14-26 at.% (up to 20 at.% O, 1.7 at.% C, 1.0 at.% N, 1.3 at.% Ni and under 0.1 at.% W). The surface composition indicates gettering of O and a long-term retention of N. The Be thickness on the tile exposed to ILW1-2 was between 7.6 and 9.7 mu m, thus indicating erosion in some areas, while the thickness after ILW1-3 increased to 10-12 mu m. The D content was in the range 1.2-3.4x10(17) cm(-2) after ILW1-2 and 3.2-10x10(17) cm(-2) after ILW1-3 on most of the analyzed area, but in the limiter shadow values up to 58 x10(17) cm(-2) were measured. Taking into account the total area of the Be-coated inner wall cladding tiles, the lower limit of D inventory amounts to 5.3x10(22) atoms corresponding to about 176 mg, i.e. somewhat greater than the amount determined on Be limiters. The formation and spalling-off of Be-O particles was revealed.

  • 41.
    Drenik, A.
    et al.
    Max Planck Inst Plasma Phys, D-85748 Garching, Germany.;Max Planck Inst Plasma Phys, D-85748 Garching, Germany.;Slovenian Fusion Assoc, Jozef Stefan Inst, Jamova 39, SI-1000 Ljubljana, Slovenia..
    Bergsåker, Henric
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Bykov, Igor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Frassinetti, Lorenzo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Garcia-Carrasco, Alvaro
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Hellsten, Torbjörn
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Johnson, Thomas
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Menmuir, Sheena
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Petersson, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Rachlew, Elisabeth
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Ratynskaia, Svetlana
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Stefanikova, Estera
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Ström, Petter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Tholerus, Emmi
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Tolias, Panagiotis
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Olivares, Pablo Vallejos
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Weckmann, Armin
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Zhou, Yushun
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik. KTH, Fusion Plasma Phys, EES, SE-10044 Stockholm, Sweden..
    Zychor, I.
    Natl Ctr Nucl Res, PL-05400 Otwock, Poland..
    Evaluation of the plasma hydrogen isotope content by residual gas analysis at JET and AUG2017Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, artikkel-id 014021Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The isotope content of the plasma reflects on the dynamics of isotope changeover experiments, efficiency of wall conditioning and the performance of a fusion device in the active phase of operation. The assessment of the isotope ratio of hydrogen and methane molecules is used as a novel method of assessing the plasma isotope ratios at JET and ASDEX-Upgrade (AUG). The isotope ratios of both molecules in general shows similar trends as the isotope ratio detected by other diagnostics. At JET, the absolute values of RGA signals are in relatively good agreement with each other and with spectroscopy data, while at AUG the deviation from neutral particle analyser data are larger, and the results show a consistent spatial distribution of the isotope ratio. It is further shown that the isotope ratio of the hydrogen molecule can be used to study the degree of dissociation of the injected gas during changeover experiments.

  • 42.
    Eichhorn, Ralf
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Aurell, Erik
    KTH, Skolan för datavetenskap och kommunikation (CSC), Beräkningsbiologi, CB. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Stochastic thermodynamics2014Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 89, nr 4, s. 048001-Artikkel i tidsskrift (Fagfellevurdert)
  • 43.
    Erdal, Suvar
    et al.
    KTH, Tidigare Institutioner (före 2005), Mikroelektronik och informationsteknik, IMIT.
    Haralson, Erik
    KTH, Tidigare Institutioner (före 2005), Mikroelektronik och informationsteknik, IMIT.
    Radamson, Henry H.
    KTH, Tidigare Institutioner (före 2005), Mikroelektronik och informationsteknik, IMIT.
    Wang, Yong-Bin
    KTH, Tidigare Institutioner (före 2005), Mikroelektronik och informationsteknik, IMIT.
    Malm, B. Gunnar
    KTH, Tidigare Institutioner (före 2005), Mikroelektronik och informationsteknik, IMIT.
    Östling, Mikael
    KTH, Tidigare Institutioner (före 2005), Mikroelektronik och informationsteknik, IMIT.
    High frequency performance of SiGeCHBTs with selectively & non-selectively grown collector2004Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T114, s. 138-141Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two high-frequency heterojunction bipolar transistor (HBT) architectures based on SiGeC have been fabricated and characterized. Different collector designs were applied either by using selective epitaxial growth doped with phosphorous or by non-selective epitaxial growth doped with arsenic. Both designs have a non-selectively deposited SiGeC base doped with boron and a poly-crystalline emitter doped with phosphorous. Both HBT designs exhibit similar electrical characteristics with a peak DC current gain of around 1600 and a BVCEO of 1.8V. The cut-off frequency (f(T)) and maximum frequency of oscillation (f(max)) vary from 40-80 GHz and 15-30 GHz, respectively, depending on lateral design relations. Good high frequency performance for a device with a selectively grown collector is demonstrated for the first time.

  • 44.
    Forslund, Ola Kenji
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik.
    Andreica, Daniel
    Ioan Ursu Institute, Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania .
    Ohta, Hiroto
    Faculty of Science and Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan .
    Imai, Masaki
    Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 Japan .
    Michioka, Chishiro
    Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 Japan .
    Yoshimura, Kazuyoshi
    Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 Japan .
    Månsson, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik.
    Sugiyama, Jun
    Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan 6 Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan .
    Co-existence of short- and long-range magnetic order in LaCo2P22021Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 96, nr 12, s. 125864-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ferromagnetic (FM) nature of the metallic LaCo2P2 was investigated with the positive muon spin rotation, relaxation and resonance (μ+SR) technique. Transverse and zero field μ+ SR measurements revealed that the compound enters a long range FM ground state at   K, consistent with previous studies. Based on the reported FM structure, the internal magnetic field was computed at the muon sites, which were predicted with first principles calculations. The computed result agree well with the experimental data. Moreover, although LaCo2P2 is a paramagnet at higher temperatures T > 160 K, it enters a short range ordered (SRO) magnetic phase for   K. Measurements below the vicinity of   revealed that the SRO phase co-exists with the long range FM order at temperatures 124 K  . Such co-existence is an intrinsic property and may be explained by an interplay between spin and lattice degree of freedoms.

    Fulltekst (pdf)
    fulltext
  • 45. Fortuna, E.
    et al.
    Rubel, Marek J.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Psoda, M.
    Andrzejczuk, M.
    Kurzydlowski, K. J.
    Miskiewicz, M.
    Philipps, V.
    Pospieszczyk, A.
    Sergienko, G.
    Spychalski, M.
    Zielinski, W.
    Plasma-induced damage of tungsten coatings on graphite limiters2007Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T128, s. 162-165Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Vaccum plasma sprayed tungsten coatings with an evaporated sandwich Re - W interlayer on graphite limiter blocks were studied after the experimental campaign in the TEXTOR tokamak. The coating morphology was modified by high-heat loads and co-deposition of species from the plasma. Co-deposits contained fuel species, carbon, boron and silicon. X-ray diffractometer phase analysis indicated the coexistence of metallic tungsten and its carbides (WC and W2C) and boride (W2B). In the Re - W layer the presence of carbon was detected in a several micrometres thick zone. In the overheated part of the limiter, the Re - W layer was transformed into a sigma phase.

  • 46. Fortuna-Zalesna, E.
    et al.
    Grzonka, J.
    Moon, Sunwoo
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Petersson, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Widdowson, A.
    Fine metal dust particles on the wall probes from JET-ILW2017Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, artikkel-id 014038Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 47.
    Fortuna-Zalesna, E.
    et al.
    Warsaw Univ Technol, PL-02507 Warsaw, Poland..
    Plocinski, T.
    Warsaw Univ Technol, PL-02507 Warsaw, Poland..
    Moon, Sunwoo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Petersson, Per
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Rubel, Marek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Widdowson, A.
    Culham Sci Ctr, CCFCE, Abingdon OX14 3DB, Oxon, England..
    Dust generation and accumulation in JET-ILW: morphology and stability of co-deposits on main plasma-facing components and wall probes2021Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 96, nr 12, artikkel-id 124038Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dust particles and co-deposits were sampled for the first time from beryllium limiters and bulk tungsten divertor (both after ILW-3), and test mirrors from the main chamber after ILW-2 and ILW-3. The focus was on the morphology of molten particles and metal outgrowths. In parallel, the stability of beryllium layers under the impact of hot water was examined on limiters and Be coatings. The study performed by several microscopy methods including SEM, AFM, FIB, TEM and Be-sensitive EDX has revealed: (i) an asymmetric distribution of Be particles with the largest objects (125-550 mu m) on side surfaces of the Be tile: (ii) the presence of highly porous particles, resembling blisters; (iii) very few thin flakes of co-deposits on the divertor, on the shadowed edge of lamella; (iv) the elemental composition and internal structure of the needle-shaped outgrowths on the mirrors: MoO; (v) no detectable impact of water on the beryllium morphology.

  • 48. Fortuna-Zalesna, E.
    et al.
    Weckmann, Armin
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Grozonka, J.
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Esser, H. G.
    Freisinger, M.
    Kreter, A.
    Kischner, A.
    Sergienko, G.
    Ström, Petter
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Dust Survey Following the Final Shutdown of TEXTOR: Metal Particles and Fuel Retention2016Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T167, artikkel-id 014059Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 49.
    Fortuna-Zalesna, E.
    et al.
    Warsaw Univ Technol, Fac Mat Sci & Engn, Warsaw, Poland..
    Zielinski, W.
    Warsaw Univ Technol, Fac Mat Sci & Engn, Warsaw, Poland..
    Plocinski, T.
    Warsaw Univ Technol, Fac Mat Sci & Engn, Warsaw, Poland..
    Weckmann, Armin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Kreter, A.
    Forschungszentrum Julich, Inst Energie & Klimaforsch Plasmaphys, D-52425 Julich, Germany..
    Brezinsek, S.
    Forschungszentrum Julich, Inst Energie & Klimaforsch Plasmaphys, D-52425 Julich, Germany..
    Bazarnik, P.
    Warsaw Univ Technol, Fac Mat Sci & Engn, Warsaw, Poland..
    Rubel, Marek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Fusionsplasmafysik.
    Decommissioning of TEXTOR: properties of the Inconel liner2020Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T171, nr 1, artikkel-id 014036Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The final shut-down of Tokamak Experiment for Technology Oriented Research in year 2013 created unique opportunities for multi-directional studies of in-vessel components. A set of specimens from the Inconel liner parts was collected in order to assess material properties after 26 years of exploitation. The metal surfaces were covered with up to several mu m thick co-deposits rich in boron, carbon and silicon. Detailed examination of the co-deposits and nearsurface structure of Inconel performed with Transmission Electron Microscopy (TEM) revealed: (i) stratified character of the deposits; (ii) a similar to 200 nm thick layer identified as NiSi2 phase at the interface between the deposit and Inconel substrate; (iii) changed Inconel surface layer. TEM studies of the Inconel structure revealed its polycrystalline character with a mean grain size, low dislocation density and a significant number of heterogeneously distributed primary carbides.

  • 50. Gaarder, A.
    et al.
    Marcinkevicius, Saulius
    KTH, Tidigare Institutioner (före 2005), Mikroelektronik och informationsteknik, IMIT.
    Barrios, C. A.
    Lourdudoss, Sebastian
    KTH, Tidigare Institutioner (före 2005), Mikroelektronik och informationsteknik, IMIT.
    Time-resolved micro-photoluminescence studies of dopant distribution in selectively regrown GalnP: Fe around VCSELs2002Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T101, s. 89-91Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We apply time-resolved photoluminescence with 1.5 mum spatial resolution for characterization ofcarrier trap distribution in semi-insulating Ga0.51In0.49P:Fe layers regrown around GaAs/AlGaAs circular vertical cavity surface emitting laser mesas using hydride vapour phase epitaxy. The carrier trapping times are in the range from 10 to 15 ps and quite uniformly distributed throughout the burying GaInP:Fe layer, suggesting that the layer is semi-insulating everywhere. Simulations show that, in addition to the Fe dopants, the layer contains other, unintended carrier traps. The photoluminescence spectra reveal that the regrown GaInP:Fe material has several distinct regions with different band gaps. This is attributed to differences in the In/Ga composition and/or CuPt ordering of the GaInP.

1234 1 - 50 of 183
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