| 1. |
- 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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| 2. |
- 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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| 3. |
- Conde, E, et al.
(författare)
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Effects of the COVID-19 Health Crisis on Sports Practice, Life Quality, and Emotional Status in Spanish High-Performance Athletes
- 2021
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Ingår i: Frontiers in psychology. - : Frontiers Media SA. - 1664-1078. ; 12, s. 736499-
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Tidskriftsartikel (refereegranskat)abstract
- Spain is one of the many countries highly affected by the COVID-19 crisis, establishing very restrictive measures with a complete lockdown for more than 3 months. This situation forced the complete closure of sport practice and national or international competitions, leading to a negative impact on physical and psychological health of high-performance athletes. Therefore, the objectives of this study were (a) to determine the effects of the COVID-19 health crisis on Spanish high-performance athletes in terms of sports practice, life quality, and emotional state and (b) to identify the profile with the greatest difficulties during and after the lockdown. A sample of 130 high-performance athletes aged between 18 and 34 years (67 women and 63 men) participated in this study (83.1% achieved a medal in National–International elite competitions; 86.9% were considered student-athletes). Measures included socio-demographic data through a 5-dimension ad hoc survey: physical activity and exercise using an adapted version from the International Physical Activity Questionnaire (IPAQ); health status and limitations using an adapted version of SF-12 Health Questionnaire; Perceived stress (Short-PSS); and Mood States (29-item POMS). All participants have shown a significant decrease pre–post-lockdown in both health and performance perception, especially in women, individual athletes, medalists, and student-athletes. Strong limitations of training, attention, and motivation as well as a moderate negative emotional state during lockdown were reported, in women, individual athletes, medalists, and student-athletes. Even with an improved emotional state and energy level in the post-lockdown period, moderate-to-high stress scores were reported by women and medalists. Our findings highlight the importance of paying attention to the physical and psychological health of elite athletes on three profiles: team athletes (due to social distance), student-athletes (dual-career issues), and women athletes (prevalence of implicit gender inequalities in sport).
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