| 1. |
- Abel, I, et al.
(författare)
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Overview of the JET results with the ITER-like wall
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104002-
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Tidskriftsartikel (refereegranskat)abstract
- Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Z(eff) (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H-98,H-y2 close to 1 and beta(N) similar to 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential.
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| 2. |
- Romanelli, F, et al.
(författare)
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Overview of the JET results
- 2011
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 51:9
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Tidskriftsartikel (refereegranskat)abstract
- Since the last IAEA Conference JET has been in operation for one year with a programmatic focus on the qualification of ITER operating scenarios, the consolidation of ITER design choices and preparation for plasma operation with the ITER-like wall presently being installed in JET. Good progress has been achieved, including stationary ELMy H-mode operation at 4.5 MA. The high confinement hybrid scenario has been extended to high triangularity, lower ρ*and to pulse lengths comparable to the resistive time. The steady-state scenario has also been extended to lower ρ*and ν*and optimized to simultaneously achieve, under stationary conditions, ITER-like values of all other relevant normalized parameters. A dedicated helium campaign has allowed key aspects of plasma control and H-mode operation for the ITER non-activated phase to be evaluated. Effective sawtooth control by fast ions has been demonstrated with3He minority ICRH, a scenario with negligible minority current drive. Edge localized mode (ELM) control studies using external n = 1 and n = 2 perturbation fields have found a resonance effect in ELM frequency for specific q95values. Complete ELM suppression has, however, not been observed, even with an edge Chirikov parameter larger than 1. Pellet ELM pacing has been demonstrated and the minimum pellet size needed to trigger an ELM has been estimated. For both natural and mitigated ELMs a broadening of the divertor ELM-wetted area with increasing ELM size has been found. In disruption studies with massive gas injection up to 50% of the thermal energy could be radiated before, and 20% during, the thermal quench. Halo currents could be reduced by 60% and, using argon/deuterium and neon/deuterium gas mixtures, runaway electron generation could be avoided. Most objectives of the ITER-like ICRH antenna have been demonstrated; matching with closely packed straps, ELM resilience, scattering matrix arc detection and operation at high power density (6.2 MW m-2) and antenna strap voltages (42 kV). Coupling measurements are in very good agreement with TOPICA modelling. © 2011 IAEA, Vienna.
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| 3. |
- Bécoulet, A., et al.
(författare)
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Science and technology research and development in support to ITER and the Broader Approach at CEA
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10
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Tidskriftsartikel (refereegranskat)abstract
- In parallel to the direct contribution to the procurement phase of ITER and Broader Approach, CEA has initiated research & development programmes, accompanied by experiments together with a significant modelling effort, aimed at ensuring robust operation, plasma performance, as well as mitigating the risks of the procurement phase. This overview reports the latest progress in both fusion science and technology including many areas, namely the mitigation of superconducting magnet quenches, disruption-generated runaway electrons, edge-localized modes (ELMs), the development of imaging surveillance, and heating and current drive systems for steady-state operation. The WEST (W Environment for Steady-state Tokamaks) project, turning Tore Supra into an actively cooled W-divertor platform open to the ITER partners and industries, is presented.
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| 4. |
- Pegourie, B., et al.
(författare)
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Deuterium inventory in Tore Supra : Coupled carbon-deuterium balance
- 2013
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 438:Suppl., s. S120-S125
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an analysis of the carbon-deuterium circulation and the resulting balance in Tore Supra over the period 2002-2007. Carbon balance combines the estimation of carbon gross erosion from spectroscopy, net erosion and deposition using confocal microscopy, lock-in thermography and SEM, and a measure of the amount of deposits collected in the vacuum chamber. Fuel retention is determined from post-mortem (PM) analyses and gas balance (GB) measurements. Special attention was paid to the deuterium outgassed during the nights and weekends of the experimental campaign (vessel under vacuum, Plasma Facing Components at 120 degrees C) and during vents (vessel at atmospheric pressure, PFCs at room temperature). It is shown that this outgassing is the main process reconciling the PM and GB estimations of fuel retention, closing the coupled carbon-deuterium balance. In particular, it explains why the deuterium concentration in deposits decreases with increasing depth.
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| 5. |
- Carbajal, Ricardo, et al.
(författare)
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Pain Assessment in Ventilated and Non-Ventilated Neonates in NICUs across Europe : EUROpean Pain Audit in Neonates (EUROPAIN Survey)
- 2014
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Konferensbidrag (refereegranskat)abstract
- Background: Neonates undergo many painful procedures during their NICU stay. These may include tracheal intubation/ventilation, skin-breaking procedures, drainage/suctioning of body orifices or cavities. Inherent subjectivity and difficulties of neonatal pain assessment contribute to a wide variety of assessment tools and clinical practices. To date, these practices have been not studied at a large scale. OBJECTIVE: To determine current clinical practices for neonatal pain assessment in NICUs across Europe. DESIGN/METHODS: An epidemiological observational study on bedside pain assessment practices collected data for all neonates in participating NICUs until infants left the unit (discharge, death, transfer to another hospital) or for 28 days. Data collection occurred via an online database for 1 month at each NICU. All neonates up to a gestational age of 44 weeks were included. RESULTS: From October 2012 to June 2013, 243 NICUs from 18 European countries collected pain assessment data in 6680 neonates. Of these, 2142 received tracheal ventilation (ventilated) and 4538 had spontaneous breathing or non- invasive ventilation (non-ventilated). The median (IQR) gestational age of ventilated neonates [32.1 (28.1-37.4)] was less than non-ventilated neonates [36.6 (33.6-39.1), p<0.001]. Overall, 58.5% of ventilated neonates and 35.2%% of non-ventilated neonates received bedside pain assessments (p<0.001). CONCLUSIONS: Over half (58.5%) of ventilated neonates and about one third (35.2%) of non-ventilated neonates had pain assessments performed in European NICUs. Wide variations in the methods used and rates of pain assessment exist among countries
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| 6. |
- Carbajal, Ricardo, et al.
(författare)
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Pain Assessment In Ventilated And Non-ventilated Neonates In Nicus Across Europe : European Pain Audit In Neonates (europain Survey)
- 2014
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Ingår i: Archives of Disease in Childhood. - London, United Kingdom : BMJ Publishing Group Ltd. - 0003-9888 .- 1468-2044. ; 99, s. A68-A68
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Tidskriftsartikel (refereegranskat)abstract
- Background: Neonates undergo many painful procedures during their NICU stay. These may include tracheal intubation/ventilation, skin-breaking procedures, drainage/suctioning of body orifices or cavities. Inherent subjectivity and difficulties of neonatal pain assessment contribute to a wide variety of assessment tools and clinical practices. To date, these practices have been not studied at a large scale.Objective: To determine current clinical practices for neonatal pain assessment in NICUs across Europe.Methods: An epidemiological observational study on bedside pain assessment practices collected data for all neonates in participating NICUs until infants left the unit (discharge, death, transfer to another hospital) or for 28 days. Data collection occurred via an online database for 1 month at each NICU. All neonates up to a gestational age of 44 weeks were included.Results: From October 2012 to June 2013, 243 NICUs from 18 European countries collected pain assessment data in 6680 neonates. Of these, 2142 received tracheal ventilation (TV), 1496 non-invasive ventilation (NIV) and 3042 only spontaneous ventilation (SV). The median (IQR) gestational age of TV, NIV and SV neonates were 32.1 (28.1–37.4), 33.6 (31.0–36.6) and 37.9 (35.0–39.9), respectively (p < 0.001). Overall, 58.5% of TV neonates, 45.0% of NIV neonates and 30.4% of SV neonates received bedside pain assessments (p < 0.001). Fig. shows pain assessments by country.Conclusions: Over half (58.5%) of TV neonates and less than half (45.0%) of NIV neonates had pain assessments performed in European NICUs. Wide variations in the rates of pain assessment exist among countries and an important improvement seems necessary.
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| 7. |
- Carbajal, Ricardo, et al.
(författare)
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Sedation And Analgesia For Neonates In Nicus Across Europe : The Europain Survey
- 2014
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Ingår i: Archives of Disease in Childhood. - London, United Kingdom : BMJ Publishing Group Ltd. - 0003-9888 .- 1468-2044. ; 99, s. A64-A64
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Tidskriftsartikel (refereegranskat)abstract
- Background: Pain and stress induced by mechanical ventilation, invasive procedures, or painful diseases supports the use of sedation/analgesia (S/A) in newborns admitted to Neonatal Intensive Care Units (NICUs). To date, these practices have not been studied at a large scale.Objective: To determine current clinical practices regarding the use of S/A drugs in NICUs across Europe.Methods: This epidemiological observational study on bedside clinical practices regarding S/A collected data for all neonates in participating NICUs until the infant left the unit (discharge, death, transfer) or for up to 28 days. Data collection occurred via an online database for 1 month at each NICU. All neonates up to 44 weeks gestation were included.Results: From October 2012 to June 2013, 243 NICUs from 18 European countries collected data on 6680 eligible neonates. Of these, 2142 received tracheal ventilation (TV), 1496 non-invasive ventilation (NIV) and 3042 only spontaneous ventilation (SV). The median (IQR) gestational age of TV, NIV and SV neonates were 32.1 (28.1–37.4), 33.6 (31.0–36.6) and 37.9 (35.0–39.9), respectively (p < 0.001). Overall, more TV neonates [81.5% (n = 1746)] received S/A drugs than NIV neonates [17.8% (n = 266)] and SV neonates [9.3% (n = 282)]; p < 0.001. Fig. shows the rate of S/A use by country; table shows S/A drugs used.Conclusions: Most ventilated but few non-ventilated neonates (NIV and SV) receive S/A therapy in European NICUs. Wide variations in S/A use, drugs used, and mode of administration (continuous, bolus, or both) exist among countries.
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| 8. |
- Fischer, M., et al.
(författare)
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Structural analysis of diamond mosaic crystals for neutron monochromators using synchrotron radiation
- 2013
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Ingår i: Diamond and Related Materials. - : Elsevier BV. - 0925-9635. ; 37, s. 41-49
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Tidskriftsartikel (refereegranskat)abstract
- The beams extracted from thermal neutron sources such as nuclear reactors are monochromatised by Bragg diffraction using imperfect single crystals with an angular mosaic spread of typically 0.2-0.8 degrees. For neutron wavelengths below 1.5 angstrom, the highest reflectivity of all crystalline materials is expected for diamond. Nowadays diamond single crystals with an appropriate mosaic spread exceeding a thickness of 1 mm can be grown by heteroepitaxy on an Ir/yttria-stabilised zirconia bilayer deposited on a Si(001) single crystal. To explain the observed neutron reflectivity being below the theoretically expected value, we have studied the spatial distribution of the mosaic structure of two crystals by high resolution X-ray diffraction using a laboratory X-ray source and synchrotron radiation. The first sample (A) showed a uniform mosaic spread of 0.18 degrees +/- 0.02 degrees across the 1 cm wide sample. The peak shift of the X-ray rocking curves of 0.08 degrees indicated a weak curvature of the crystal lattice. The measured absolute neutron peak reflectivity of 34% corresponded to 90% of the value predicted by theory. The peak width of the neutron rocking curve for the second sample (B) was twice as big, but here the peak reflectivity of 13% corresponded to only half of the theoretical value. This unfavourable behaviour could be assigned to a substantial spatial variation of the mosaic spread deduced from the synchrotron X-ray studies. X-ray diffraction with high spatial resolution indicated a mosaic block size below 50 pm for sample A. This was consistent with chemical etching experiments on the surface of a comparable sample which showed both randomly distributed dislocations and others that are arranged in boundaries of several 10 mu m large domains. (C) 2013 Elsevier B.V. All rights reserved.
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| 9. |
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