| 1. |
- Zohm, H., et al.
(författare)
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Overview of ASDEX upgrade results in view of ITER and DEMO
- 2024
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Ingår i: Nuclear Fusion. - 0029-5515 .- 1741-4326. ; 64:11
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Tidskriftsartikel (refereegranskat)abstract
- Experiments on ASDEX Upgrade (AUG) in 2021 and 2022 have addressed a number of critical issues for ITER and EU DEMO. A major objective of the AUG programme is to shed light on the underlying physics of confinement, stability, and plasma exhaust in order to allow reliable extrapolation of results obtained on present day machines to these reactor-grade devices. Concerning pedestal physics, the mitigation of edge localised modes (ELMs) using resonant magnetic perturbations (RMPs) was found to be consistent with a reduction of the linear peeling-ballooning stability threshold due to the helical deformation of the plasma. Conversely, ELM suppression by RMPs is ascribed to an increased pedestal transport that keeps the plasma away from this boundary. Candidates for this increased transport are locally enhanced turbulence and a locked magnetic island in the pedestal. The enhanced D-alpha (EDA) and quasi-continuous exhaust (QCE) regimes have been established as promising ELM-free scenarios. Here, the pressure gradient at the foot of the H-mode pedestal is reduced by a quasi-coherent mode, consistent with violation of the high-n ballooning mode stability limit there. This is suggestive that the EDA and QCE regimes have a common underlying physics origin. In the area of transport physics, full radius models for both L- and H-modes have been developed. These models predict energy confinement in AUG better than the commonly used global scaling laws, representing a large step towards the goal of predictive capability. A new momentum transport analysis framework has been developed that provides access to the intrinsic torque in the plasma core. In the field of exhaust, the X-Point Radiator (XPR), a cold and dense plasma region on closed flux surfaces close to the X-point, was described by an analytical model that provides an understanding of its formation as well as its stability, i.e., the conditions under which it transitions into a deleterious MARFE with the potential to result in a disruptive termination. With the XPR close to the divertor target, a new detached divertor concept, the compact radiative divertor, was developed. Here, the exhaust power is radiated before reaching the target, allowing close proximity of the X-point to the target. No limitations by the shallow field line angle due to the large flux expansion were observed, and sufficient compression of neutral density was demonstrated. With respect to the pumping of non-recycling impurities, the divertor enrichment was found to mainly depend on the ionisation energy of the impurity under consideration. In the area of MHD physics, analysis of the hot plasma core motion in sawtooth crashes showed good agreement with nonlinear 2-fluid simulations. This indicates that the fast reconnection observed in these events is adequately described including the pressure gradient and the electron inertia in the parallel Ohm’s law. Concerning disruption physics, a shattered pellet injection system was installed in collaboration with the ITER International Organisation. Thanks to the ability to vary the shard size distribution independently of the injection velocity, as well as its impurity admixture, it was possible to tailor the current quench rate, which is an important requirement for future large devices such as ITER. Progress was also made modelling the force reduction of VDEs induced by massive gas injection on AUG. The H-mode density limit was characterised in terms of safe operational space with a newly developed active feedback control method that allowed the stability boundary to be probed several times within a single discharge without inducing a disruptive termination. Regarding integrated operation scenarios, the role of density peaking in the confinement of the ITER baseline scenario (high plasma current) was clarified. The usual energy confinement scaling ITER98(p,y) does not capture this effect, but the more recent H20 scaling does, highlighting again the importance of developing adequate physics based models. Advanced tokamak scenarios, aiming at large non-inductive current fraction due to non-standard profiles of the safety factor in combination with high normalised plasma pressure were studied with a focus on their access conditions. A method to guide the approach of the targeted safety factor profiles was developed, and the conditions for achieving good confinement were clarified. Based on this, two types of advanced scenarios (‘hybrid’ and ‘elevated’ q-profile) were established on AUG and characterised concerning their plasma performance.
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| 2. |
- Weinstein, John N., et al.
(författare)
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The cancer genome atlas pan-cancer analysis project
- 2013
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 45:10, s. 1113-1120
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Tidskriftsartikel (refereegranskat)abstract
- The Cancer Genome Atlas (TCGA) Research Network has profiled and analyzed large numbers of human tumors to discover molecular aberrations at the DNA, RNA, protein and epigenetic levels. The resulting rich data provide a major opportunity to develop an integrated picture of commonalities, differences and emergent themes across tumor lineages. The Pan-Cancer initiative compares the first 12 tumor types profiled by TCGA. Analysis of the molecular aberrations and their functional roles across tumor types will teach us how to extend therapies effective in one cancer type to others with a similar genomic profile. © 2013 Nature America, Inc. All rights reserved.
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| 3. |
- Chen, W., et al.
(författare)
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Enhanced efficiency of polymer solar cells by improving molecular aggregation and broadening the absorption spectra
- 2019
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Ingår i: Dyes and Pigments. - : Elsevier BV. - 0143-7208 .- 1873-3743. ; 166, s. 42-48
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Tidskriftsartikel (refereegranskat)abstract
- Alkylthio-substituted thiophene-based benzo[1,2-b:4,5-b’]dithiophene (BDT) was used to construct PBDTS-DTBT, a medium band gap donor-acceptor (D-A) polymer with 5,6-difluoro-4,7-bis[4-(2-octyldodecyl)thiophene-2-yl]benzo[c] [1,2,5]thiadiazole (DTBT). The incorporation of sulfur atoms into the side chains not only lowered the highest occupied molecular orbital (HOMO) energy level but also improved molecular aggregation and thus afforded lower band gap (1.68 eV) with full width at half maximum (FWHM) of 170 nm in comparison to that of the analogous polymer (PBDT-DTBT) without sulfur atoms in side chains. Therefore, the bulk heterojunction polymer solar cells based on PBDTS-DTBT with 2% diiodooctane (DIO) as processing additive showed a high power conversion efficiency (PCE) of 9.73% with high open-circuit voltage (V OC , 0.93 V), large short-circuit current density (J SC , 14.23 mA/cm 2 ) and high fill factor (FF, 0.735).
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| 4. |
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| 5. |
- Grieser, M., et al.
(författare)
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Storage ring at HIE-ISOLDE
- 2012
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Ingår i: European Physical Journal: Special Topics. - : Springer Science and Business Media LLC. - 1951-6401 .- 1951-6355. ; 207:1, s. 1-117
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Tidskriftsartikel (refereegranskat)abstract
- We propose to install a storage ring at an ISOL-type radioactive beam facility for the first time. Specifically, we intend to setup the heavy-ion, low-energy ring TSR at the HIE-ISOLDE facility in CERN, Geneva. Such a facility will provide a capability for experiments with stored secondary beams that is unique in the world. The envisaged physics programme is rich and varied, spanning from investigations of nuclear ground-state properties and reaction studies of astrophysical relevance, to investigations with highly-charged ions and pure isomeric beams. The TSR might also be employed for removal of isobaric contaminants from stored ion beams and for systematic studies within the neutrino beam programme. In addition to experiments performed using beams recirculating within the ring, cooled beams can also be extracted and exploited by external spectrometers for high-precision measurements. The existing TSR, which is presently in operation at the Max-Planck Institute for Nuclear Physics in Heidelberg, is well-suited and can be employed for this purpose. The physics cases as well as technical details of the existing ring facility and of the beam and infrastructure requirements at HIE-ISOLDE are discussed in the present technical design report.
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| 6. |
- Ankowski, A., et al.
(författare)
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Energy reconstruction of electromagnetic showers from Ν0 decays with the ICARUS T600 liquid argon TPC
- 2010
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Ingår i: Acta Physica Polonica, Series B.. - 1509-5770 .- 0587-4254. ; 41:1, s. 103-125
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the ICARUS T600 detector capabilities in electromagnetic shower reconstruction through the analysis of a sample of 212 events, coming from the 2001 Pavia surface test run, of hadronic interactions leading to the production of π 0 mesons. Methods of shower energy and shower direction measurements were developed and the invariant mass of the photon pairs was reconstructed. The (γγ) invariant mass was found to be consistent with the value of the π 0 mass. The resolution of the reconstructed π 0 mass was found to be equal to 27.3%. An improved analysis, carried out in order to clean the full event sample from the events measured in the crowded environment, mostly due to the trigger conditions, gave a π 0 mass resolution of 16.1%, significantly better than the one evaluated for the full event sample. The trigger requirement of the coincidence of at least four photo-multiplier signals favored the selection of events with a strong pile up of cosmic ray tracks and interactions. Hence a number of candidate π 0 events were heavily contaminated by other tracks and had to be rejected. Monte Carlo simulations of events with π 0 production in hadronic and neutrino interactions confirmed the validity of the shower energy and shower direction reconstruction methods applied to the real data.
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| 7. |
- Fu, L., et al.
(författare)
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Effects of Cr3C2 content and temperature on sliding friction and wear behaviors of Cr3C2/Ni3Al composite materials
- 2018
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Ingår i: Wear. - : Elsevier BV. - 0043-1648. ; 414-415, s. 163-173
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Tidskriftsartikel (refereegranskat)abstract
- Chromium carbide (Cr3C2)-reinforced Ni3Al matrix composites, which possess excellent high-temperature strength and wear resistance, are considered as potential high-temperature wear-resistant materials. In this study, effects of Cr3C2content on the friction and wear properties of Cr3C2/Ni3Al composites and their counterpart gray cast iron disks were investigated at different temperatures. The worn surface morphologies of the Cr3C2/Ni3Al composites and gray cast iron disks were analyzed to understand their wear mechanisms. The analysis results showed that in the Ni3Al matrix composites, a combination of abrasive wear and adhesive wear occurred at room temperature, whereas adhesive wear was severer at 200 °C. Furthermore, the optimum Cr3C2contents of the Cr3C2/Ni3Al composites were found to be 18 vol% and 12 vol% at room temperature and 200 °C, respectively. The volume loss of the composites increased with an increase in the fraction of the Cr3C2strengthening phase at 350 °C. The wear resistance of the gray cast iron disks decreased with an increase in temperature. In contrast, the wear resistance of the Ni3Al matrix composites increased with an increase in temperature. This increased wear resistance of the composites is attributed to the transformation of their wear mechanism with increasing temperature.
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| 8. |
- Fu, L., et al.
(författare)
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Wear mechanism of Cr 3 C 2 /Ni 3 Al composites showing excellent wear resistance
- 2019
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Ingår i: Gongcheng Kexue Xuebao/Chinese Journal of Engineering. - 2095-9389. ; 41:1, s. 117-123
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Tidskriftsartikel (refereegranskat)abstract
- The Ni 3 Al intermetallic compound is considered an excellent wear-resistant material. The addition of Cr 3 C 2 particles can further improve the wear resistance of Ni 3 Al-based alloys. In order to elucidate the wear mechanism of Cr 3 C 2 /Ni 3 Al composites improved by the Cr 3 C 2 strengthening phase, Ni 3 Al-alloy and Cr 3 C 2 /Ni 3 Al composites were prepared by the hot isostatic pressing process in this study. The mechanical properties and wear resistance of each phase in the Ni 3 Al-alloy and Cr 3 C 2 /Ni 3 Al composites were investigated using a nano-indentation instrument and a pin-on-disk friction and wear tester, respectively. The worn surface morphologies and the hardness of the subsurface layer under the worn surfaces of the Ni 3 Al-alloy and Cr 3 C 2 /Ni 3 Al composites were determined by a scanning electron microscopy (SEM) and a nano-indentation instrument. The results indicate that the hardness of the matrix phase in the Cr 3 C 2 /Ni 3 Al composites is significantly improved by the addition of Cr 3 C 2 particles. The nano-hardness and the elastic modulus of each phase in the Cr 3 C 2 /Ni 3 Al composites gradually increase from matrix phase through diffusion phase to hard core phase. The mechanical properties between the matrix, diffusion, and hard core phases in the Cr 3 C 2 /Ni 3 Al composites present a gradient transition. This kind of structure distribution is good for enhancing the wear resistance of Cr 3 C 2 /Ni 3 Al composite materials. As for friction and wear conditions in this study, abrasive wear was the dominant wear mechanism, which occurred on the surfaces of the Ni 3 Al-alloy and Cr 3 C 2 /Ni 3 Al composites. The Cr 3 C 2 /Ni 3 Al composites showed a good wear resistant property. The carbide-strengthening phase can block up the cutting action of the wear debris, reduce the interaction between the wear materials, and decrease the thickness of the subsurface layer and the size of the wear debris, resulting in improved wear resistance of Cr 3 C 2 /Ni 3 Al composites.
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| 9. |
- Iliev, M. N., et al.
(författare)
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Comparative Raman studies of Sr2RuO4, Sr 3Ru2O7 and Sr4Ru3O 10
- 2005
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Ingår i: Physica B: Condensed Matter. - : Elsevier BV. - 0921-4526. ; 358:1-4, s. 138-152
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Tidskriftsartikel (refereegranskat)abstract
- The polarized Raman spectra of layered ruthenates of the Srn+1RunO3n+1 (n=1,2,3) Ruddlesden-Popper series were measured between 10 and 300 K. The phonon spectra of Sr3Ru2O7 and Sr4Ru3O10 confirmed earlier reports for correlated rotations of neighboring RuO6 octahedra within double or triple perovskite blocks. The observed Raman lines of Ag or B1g symmetry were assigned to particular atomic vibrations by considering the Raman modes in simplified structures with only one double or triple RuO6 layer per unit cell and by comparison to the predictions of lattice dynamical calculations for the real Pban and Pbam structures. Along with discrete phonon lines, a continuum scattering, presumably of electronic origin, is present in the zz, xx and xy, but not in the x′y′ and zx spectra. Its interference with phonons results in Fano shape for some of the lines in the xx and xy spectra. The temperature dependences of phonon parameters of Sr3Ru2O7 exhibit no anomaly between 10 and 300 K where no magnetic transition occur. In contrast, two B1g lines in the spectra of Sr4Ru3O10, corresponding to oxygen vibrations modulating the Ru-O-Ru bond angle, show noticeable hardening with ferromagnetic ordering at 105 K, thus indicating strong spin-phonon interaction.
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| 10. |
- Li, Zhaojun, 1989, et al.
(författare)
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High Performance All-Polymer Solar Cells by Synergistic Effects of Fine-Tuned Crystallinity and Solvent Annealing.
- 2016
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 138:34, s. 10935-44
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Tidskriftsartikel (refereegranskat)abstract
- Growing interests have been devoted to the design of polymer acceptors as potential replacement for fullerene derivatives for high-performance all polymer solar cells (all-PSCs). One key factor that is limiting the efficiency of all-PSCs is the low fill factor (FF) (normally
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