| 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. |
- Kiptily, V. G., et al.
(författare)
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Fusion Alpha-Particle Diagnostics for DT Experiments on the Joint European Torus
- 2014
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Ingår i: FUSION REACTOR DIAGNOSTICS. - : AIP Publishing LLC. ; , s. 87-92
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Konferensbidrag (refereegranskat)abstract
- JET equipped with ITER-like wall (a beryllium wall and a tungsten divertor) can provide auxiliary heating with power up to 35MW, producing a significant population of alpha-particles in DT operation. The direct measurements of alphas are very difficult and alpha-particle studies require a significant development of dedicated diagnostics. JET now has an excellent set of confined and lost fast particle diagnostics for measuring the alpha-particle source and its evolution in space and time, alpha-particle energy distribution, and alpha-particle losses. This paper describes how the above mentioned JET diagnostic systems could be used for alpha-particle measurements, and what options exist for keeping the essential alpha-particle diagnostics functioning well in the presence of intense DT neutron flux. Also, alpha-particle diagnostics for ITER are discussed.
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| 4. |
- Korsholm, S. B., et al.
(författare)
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Development of novel fuel ion ratio diagnostic techniques
- 2010
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 81:10, s. 10D323-
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Tidskriftsartikel (refereegranskat)abstract
- To overcome the challenge of measuring the fuel ion ratio in the core (rho<0.3) of ITER, a coordinated effort aiming at developing diagnostic techniques has been initiated. The investigated techniques are novel uses or further development of existing methods such as charge exchange recombination spectrometry, neutron spectrometry, and collective Thomson scattering. An overview of the work on the three diagnostic techniques is presented.
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| 5. |
- Ericsson, Peter, et al.
(författare)
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Gastrin release: Antrum microdialysis reveals a complex neural control.
- 2010
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Ingår i: Regulatory Peptides. - : Elsevier BV. - 1873-1686 .- 0167-0115. ; 161, s. 22-32
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Tidskriftsartikel (refereegranskat)abstract
- We used microdialysis to monitor local gastrin release in response to food, acid blockade and acute vagal excitation. For the first time, gastrin release has been monitored continuously in intact conscious rats in a physiologically relevant experimental setting in a fashion that minimizes confounding systemic effects. Microdialysis probes were placed in the submucosa on either side of the antrum, 3days before the experiments. The concentration of gastrin in the antral submucosal compartment was 5-10 times higher than in serum regardless of the prandial state. The rats were conscious during microdialysis except when subjected to electrical vagal stimulation. Acid blockade (omeprazole treatment of freely fed rats for 4days), or bilateral sectioning of the abdominal vagal trunks (fasted rats), raised the gastrin concentration in blood as well as microdialysate. The high gastrin concentration following omeprazole treatment was not affected by vagotomy. Vagal excitation stimulated the G cells: electrical vagal stimulation and pylorus ligation (fasted rats) raised the gastrin concentration transiently in both serum and microdialysate. Food intake induced a 2- to 3-fold increase in serum gastrin, while gastrin in antral microdialysate increased 10- to 15-fold. In unilaterally vagotomized rats, food evoked a prompt peak gastrin release followed by a gradual decline on the intact side. On the vagotomized side of the antrum, the peak response seemed to be reduced while the microdialysate gastrin concentration remained elevated. Thus, unilateral vagotomy surprisingly raised the integrated gastrin response to food on the denervated side compared to the intact side, indicating that vagotomy suppresses an inhibitory as well as a stimulating effect on the G cells. While local infusion of atropine was without effect, infusion of the neuronal blocker tetrodotoxin (TTX) (which had no effect on basal gastrin) virtually abolished the food-evoked gastrin response and lowered the high microdialysate gastrin concentration in omeprazole-treated rats by 65%. We conclude that activated gastrin release, unlike basal gastrin release, is highly dependent on a neural input: 1) Vagal excitation has a transient stimulating effect on the G cells. The transient nature of the response suggests that the vagus has not only a prompt stimulatory but also a slow inhibitory effect on gastrin release. 2) Although vagal denervation did not affect the gastrin response to anacidity, the TTX experiments revealed that both food-evoked and anacidity-evoked gastrin release depends on neural input.
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| 6. |
- Hurst, HT, et al.
(författare)
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ANAEROBIC POWER AND CADENCE CHARACTERISTICS OF ELITE CROSS-COUNTRY AND DOWNHILL MOUNTAIN BIKERS
- 2012
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Ingår i: Book of Abstracts of the 17th Annual Congress of the European College of Sport Science in Bruges, Belgium from 4-7 July 2012.. - 9789090268682 ; , s. 602-603
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Konferensbidrag (refereegranskat)abstract
- Introduction Mountain biking (MTB) is composed of several sub-disciplines, with Olympic Cross-Country (XCO) and Downhill (DH) being the most popular. Much of the current research on MTB pertains to the aerobic demands of XCO racing, with comparisons often made to road cycling. No studies have compared elite level XCO and DH bikers. Therefore, the aim of this study was to investigate the anaerobic power and cadence characteristics of elite XCO to DH riders.Methods Twelve male elite mountain bikers (n=6 XCO, n=6 DH; age 21.83 ± 3.71 yrs; stature 179.67 ± 4.40 cm; mass 72.50 ± 5.45 kg) took part in this study. An inertial load cycling test was performed as described in previous studies(3),on an SRM cycle ergometer instrumented with a scientific version SRM Powermeter. Inertial load was adjusted to ensure riders achieved 130-150 revs.min-1 within 4-7 s. Peak power (Wpeak), cadence at Wpeak (CADopt) and power to weight ratio (W.kg-1) were calculated for each rider as the mean from 3 trials. Statistical differences between XCO and DH were determined using independent t-tests with significance set at p≤0.05.ResultsA significant difference between DH and XCO was found for CADopt (114.93 ± 5.41 and 107.96 ± 4.63 revs.min-1, p<0.05), respectively. No other differences were revealed between groups. The mean recorded values for DH and XCO were 1137.76 ± 135.84 and 1113.86 ± 75.22 W for Wpeak and 15.21 ± 2.05 and 15.95 ± 0.75 W.kg-1 for power to weight ratio, respectively.Discussion The findings of comparable Wpeak between groups may indicate that high anaerobic power is not a prerequisite for success in elite DH. However, significant differences were found in CADopt, where DH riders had a higher cadence when producing Wpeak compared to XCO riders. This may reflect training specificity and the greater emphasis on repeated accelerations in DH(2) and the lower cadences elicited by XCO riders(1). Further research is therefore warranted to compare laboratory and field-based performance in these two population groups.
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| 7. |
- Ivanov, Sergey A., et al.
(författare)
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Preparation, structural, dielectric and magnetic properties of LaFeO3-PbTiO3 solid solutions
- 2012
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Ingår i: Materials research bulletin. - : Elsevier BV. - 0025-5408 .- 1873-4227. ; 47:11, s. 3253-3268
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Tidskriftsartikel (refereegranskat)abstract
- Solid solutions of (1−x)LaFeO3–(x)PbTiO3 (0 < x < 1) have been prepared by conventional solid-state reaction. These complex perovskites have been studied by means of X-ray (XRPD) and neutron powder (NPD) diffraction, complemented with dielectric, magnetic, heat capacity and Mössbauer measurements. Complete solubility in the perovskite series was demonstrated. The NPD and XRPD patterns were successfully refined as orthorhombic (x ≤ 0.7) and tetragonal (x ≥ 0.8). A composition-driven phase transformation occurs within the interval 0.7 < x < 0.8. The samples with x < 0.5 showed evidence of long-range magnetic ordering with an G-type antiferromagnetic arrangement of the magnetic moments of the Fe3+ cations in the B-site with propagation vector k = (0,0,0). Based on the obtained experimental data, a combined structural and magnetic phase diagram has been constructed. The factors governing the structural, dielectric and magnetic properties of (1−x)LaFeO3–(x)PbTiO3 solid solutions are discussed, as well as their possible multiferroicity.
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| 8. |
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| 9. |
- Jacobsen, A. S., et al.
(författare)
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Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET
- 2014
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 85:11, s. 11E103-
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Tidskriftsartikel (refereegranskat)abstract
- The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutronemission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of ameasured time-of-flight spectrum from TOFOR.
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| 10. |
- Johansson, Henrik, et al.
(författare)
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Targeted resequencing of candidate genes using Selector Probes
- 2011
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 39:2, s. e8-
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Tidskriftsartikel (refereegranskat)abstract
- Targeted genome enrichment is a powerful tool for making use of the massive throughput of novel DNA-sequencing instruments. We herein present a simple and scalable protocol for multiplex amplification of target regions based on the Selector technique. The updated version exhibits improved coverage and compatibility with next-generation-sequencing (NGS) library-construction procedures for shotgun sequencing with NGS platforms. To demonstrate the performance of the technique, all 501 exons from 28 genes frequently involved in cancer were enriched for and sequenced in specimens derived from cell lines and tumor biopsies. DNA from both fresh frozen and formalin-fixed paraffin-embedded biopsies were analyzed and 94 specificity and 98 coverage of the targeted region was achieved. Reproducibility between replicates was high (R 2=0, 98) and readily enabled detection of copy-number variations. The procedure can be carried out in <24 h and does not require any dedicated instrumentation.
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